Die nachfolgende Auflistung enthält alle wissenschaftlichen Veröffentlichungen die im Rahmen des am Technologie-Campus und der Labore der beteiligten Professorinnen und Professoren entstanden sind. Dazu zählen Publikationen in Journals, Konferenzbeiträge sowie Doktorarbeiten und Buchveröffentlichungen.
2015 |
Baumer, A.; Kastenmeier, A.; Ehrlich, I. A Numerical Study of Reinforced Bolted Composite Joints. Leichtbau Inproceedings Mottok, J; Reichenberger, M; Scharfenberg, J; Ziemann, O (Hrsg.): Applied Research Conference 2015 – ARC 2015, S. 278–282, Ostbayerische Technische Hochschule Regensburg Book-On-Demand Verlag, 2015, ISBN: 978-3863869458. @inproceedings{Baumer2015, title = {A Numerical Study of Reinforced Bolted Composite Joints.}, author = {A. Baumer and A. Kastenmeier and I. Ehrlich}, editor = {J. Mottok and M. Reichenberger and J. Scharfenberg and O. Ziemann}, isbn = {978-3863869458}, year = {2015}, date = {2015-07-16}, booktitle = {Applied Research Conference 2015 – ARC 2015}, pages = {278--282}, publisher = {Book-On-Demand Verlag}, organization = {Ostbayerische Technische Hochschule Regensburg}, abstract = {The Finite Element Analysis (FEA) is an effective tool to save time and costs in the development phase of engineering disciplines. Thus the dimensioning can easily be tested and adapted with a simulation instead of expensive experiments. Manufacturing and testing of fiber-reinforced plastic components is very extensive because of their specific material properties, in comparison to metal components. This is one of the main reasons why almost each complex structure of composite material is investigated with a Finite Element Analysis. The aim of this applied research project is the analytical and numerical investigation of reinforced bolted joints at structures of carbon fiber-reinforced plastics (CFRP). Bolted joints are a relatively simple technique to join two parts of different materials with each other. However, the bolt hole reduces the bearing cross-section and induces enormous stress concentrations. That is why reinforcing bolted composite joints is necessary. In this project, it is realized with reinforcement inserts which are integrated into the laminate layup. A superior research project is investigating the load application in highly stressed tubular composite structures. Before the reinforced bolted joints are applied at tubular geometries, the reinforcing effect is investigated at plane CFRP-components in this work. Therefore, at first various laminate layups without reinforcement inserts are compared to an unidirectional (UD) laminate. After that, the inserts are integrated into the simulation of UD-laminae and compared to non-reinforced ones. Next step is the integration of reinforced laminae into an entire laminate layup to prove the general reinforcement at the load introduction spot.}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } The Finite Element Analysis (FEA) is an effective tool to save time and costs in the development phase of engineering disciplines. Thus the dimensioning can easily be tested and adapted with a simulation instead of expensive experiments. Manufacturing and testing of fiber-reinforced plastic components is very extensive because of their specific material properties, in comparison to metal components. This is one of the main reasons why almost each complex structure of composite material is investigated with a Finite Element Analysis. The aim of this applied research project is the analytical and numerical investigation of reinforced bolted joints at structures of carbon fiber-reinforced plastics (CFRP). Bolted joints are a relatively simple technique to join two parts of different materials with each other. However, the bolt hole reduces the bearing cross-section and induces enormous stress concentrations. That is why reinforcing bolted composite joints is necessary. In this project, it is realized with reinforcement inserts which are integrated into the laminate layup. A superior research project is investigating the load application in highly stressed tubular composite structures. Before the reinforced bolted joints are applied at tubular geometries, the reinforcing effect is investigated at plane CFRP-components in this work. Therefore, at first various laminate layups without reinforcement inserts are compared to an unidirectional (UD) laminate. After that, the inserts are integrated into the simulation of UD-laminae and compared to non-reinforced ones. Next step is the integration of reinforced laminae into an entire laminate layup to prove the general reinforcement at the load introduction spot. |
Niebauer, M.; Schmid, V.; Ehrlich, I. Failure Criteria of Adhesively Bonded Joints: A Review. Leichtbau Inproceedings Mottok, J; Reichenberger, M; Scharfenberg, J; Ziemann, O (Hrsg.): Applied Research Conference 2015 – ARC 2015, S. 347–351, Ostbayerische Technische Hochschule Regensburg Book-On-Demand Verlag, 2015, ISBN: 978-3863869458. @inproceedings{Niebauer2015, title = {Failure Criteria of Adhesively Bonded Joints: A Review.}, author = {M. Niebauer and V. Schmid and I. Ehrlich}, editor = {J. Mottok and M. Reichenberger and J. Scharfenberg and O. Ziemann}, isbn = {978-3863869458}, year = {2015}, date = {2015-07-16}, booktitle = {Applied Research Conference 2015 – ARC 2015}, pages = {347--351}, publisher = {Book-On-Demand Verlag}, organization = {Ostbayerische Technische Hochschule Regensburg}, abstract = {Failure criteria and predicting the critical stress state of adhesively bonded joints is one of the fundamental issues and aspects of designing adhesive bonds. Such adhesive bonded joints are used in many different applications and because of the aim to save resources and energy, engineers have to find new ways of design. A part of this can be the lightweight construction, where it is useful to design with light adhesive bonded joints. Because of this engineers have to know about the performance of such connections. This paper provides a literature review on failure criteria and strength prediction on adhesively bonded joints. The review covers articles published from 1973 until 2013 and divides the topic into several categories such as critical elastic stress states, fracture mechanics, adhesive failure due to plasticity and damage mechanics. In addition, relevant design aspects and details are discussed and available approaches, appropriate for analytical and numerical solutions are identified. }, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } Failure criteria and predicting the critical stress state of adhesively bonded joints is one of the fundamental issues and aspects of designing adhesive bonds. Such adhesive bonded joints are used in many different applications and because of the aim to save resources and energy, engineers have to find new ways of design. A part of this can be the lightweight construction, where it is useful to design with light adhesive bonded joints. Because of this engineers have to know about the performance of such connections. This paper provides a literature review on failure criteria and strength prediction on adhesively bonded joints. The review covers articles published from 1973 until 2013 and divides the topic into several categories such as critical elastic stress states, fracture mechanics, adhesive failure due to plasticity and damage mechanics. In addition, relevant design aspects and details are discussed and available approaches, appropriate for analytical and numerical solutions are identified. |
Romano, M.; Eisenried, M.; Jungbauer, B.; Ehrlich, I.; Gebbeken, N. Influence of parameters of the production process on the material quality of unidirectionally reinforced prepregs. Leichtbau Artikel Journal of Achievements in Materials and Manufacturing Engineering (JAMME), 68 (1), S. 32-44, 2015, ISSN: 1734-8412. @article{Romano2015, title = {Influence of parameters of the production process on the material quality of unidirectionally reinforced prepregs.}, author = {M. Romano and M. Eisenried and B. Jungbauer and I. Ehrlich and N. Gebbeken}, url = {http://jamme.acmsse.h2.pl/vol68_1/6815.pdf}, issn = {1734-8412}, year = {2015}, date = {2015-01-01}, journal = {Journal of Achievements in Materials and Manufacturing Engineering (JAMME)}, volume = {68}, number = {1}, pages = {32-44}, abstract = {The aim of the prepreg production device is to impregnate different types of reinforcement fibers with an arbitrarily selectable thermoset matrix system that completely satisfies the requirements for autoclave processing. As the prepreg production device is designed and built up modularly every module corresponds one step in the process. To identify the parameters of the production process and investigate its sensitivity on the material quality of both the prepreg as an uncured semi-finished product and the composite as the cured material experimental investigations regarding the resin flow, fiber volume content, mass per unit area and void content are carried out. Overall four material combinations have been investigated, where in each case the selected impregnation temperature and the width of the impregnation gap has been reproducibly varied in selected steps. The experimental characterization of the prepregs and of the composite material is carried out according to German standards. Used parameters clearly affect the material properties, so that a proper impregnation and curing process can be achieved by optimizing the parameter to desired values.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The aim of the prepreg production device is to impregnate different types of reinforcement fibers with an arbitrarily selectable thermoset matrix system that completely satisfies the requirements for autoclave processing. As the prepreg production device is designed and built up modularly every module corresponds one step in the process. To identify the parameters of the production process and investigate its sensitivity on the material quality of both the prepreg as an uncured semi-finished product and the composite as the cured material experimental investigations regarding the resin flow, fiber volume content, mass per unit area and void content are carried out. Overall four material combinations have been investigated, where in each case the selected impregnation temperature and the width of the impregnation gap has been reproducibly varied in selected steps. The experimental characterization of the prepregs and of the composite material is carried out according to German standards. Used parameters clearly affect the material properties, so that a proper impregnation and curing process can be achieved by optimizing the parameter to desired values. |
2014 |
Dinnebier, D.; Ehrlich, I. The effects of severe temperature changes and high humidity on porous CFRP. Leichtbau Artikel Journal of Achievements in Materials and Manufacturing Engineering (JAMME), 67 (1), S. 5–19, 2014. @article{Dinnebier2014, title = {The effects of severe temperature changes and high humidity on porous CFRP.}, author = {D. Dinnebier and I. Ehrlich}, year = {2014}, date = {2014-11-01}, journal = {Journal of Achievements in Materials and Manufacturing Engineering (JAMME)}, volume = {67}, number = {1}, pages = {5--19}, abstract = {A route to manufacture porous carbon fiber reinforced plastic (CFRP) for study purposes is described. The porous CFRP is characterized using standard techniques such as matrix digestion as well as the more sophisticated method of high resolution Microfocus X-Ray Tomography (μCT). A comparison of the results of those methods is presented. The mass gains of specimens with a wide range of porosity have been measured both in constant humidity and in alternating environments. It could be shown that severe temperature changes can temporarily increase the moisture content of porous CFRP. However, after the return to a constant environment, the moisture content returns back to saturation levels. Furthermore, it could be shown by X-Ray Tomography that even under severe climatic conditions no permanent liquid water condensates inside the pores. Using Microfocus Computed Tomography it could be shown that even after nearly a year under hot-wet conditions and more than 150 severe temperature cycles there is no liquid water detectable inside the pores.}, keywords = {}, pubstate = {published}, tppubtype = {article} } A route to manufacture porous carbon fiber reinforced plastic (CFRP) for study purposes is described. The porous CFRP is characterized using standard techniques such as matrix digestion as well as the more sophisticated method of high resolution Microfocus X-Ray Tomography (μCT). A comparison of the results of those methods is presented. The mass gains of specimens with a wide range of porosity have been measured both in constant humidity and in alternating environments. It could be shown that severe temperature changes can temporarily increase the moisture content of porous CFRP. However, after the return to a constant environment, the moisture content returns back to saturation levels. Furthermore, it could be shown by X-Ray Tomography that even under severe climatic conditions no permanent liquid water condensates inside the pores. Using Microfocus Computed Tomography it could be shown that even after nearly a year under hot-wet conditions and more than 150 severe temperature cycles there is no liquid water detectable inside the pores. |
Dinnebier, D.; Ehrlich, I. The Effects of Severe Temperature Changes and High Humidity on Porous CFRP. Leichtbau Inproceedings Meran, C (Hrsg.): Proceedings of the 15th International Materials Symposium (IMSP’2014), S. 433–440, Pamukkale University (Denizli, Turkey) 2014. @inproceedings{Dinnebier2014b, title = {The Effects of Severe Temperature Changes and High Humidity on Porous CFRP.}, author = {D. Dinnebier and I. Ehrlich}, editor = {C. Meran}, year = {2014}, date = {2014-10-01}, booktitle = {Proceedings of the 15th International Materials Symposium (IMSP’2014)}, pages = {433--440}, organization = {Pamukkale University (Denizli, Turkey)}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
Ehrlich, I.; Dinnebier, D.; Jost, C. Comparison of Impact Delaminations in CFRP Using Ultrasonic Testing, Microfocus Computed X-Ray Tomography and Micrographic Cross-Section. Leichtbau Inproceedings Meran, C (Hrsg.): Proceedings of the 15th International Materials Symposium (IMSP’2014), S. 441–450, Pamukkale University (Denizli, Turkey) 2014. @inproceedings{Ehrlich2014, title = {Comparison of Impact Delaminations in CFRP Using Ultrasonic Testing, Microfocus Computed X-Ray Tomography and Micrographic Cross-Section.}, author = {I. Ehrlich and D. Dinnebier and C. Jost}, editor = {C. Meran}, year = {2014}, date = {2014-10-01}, booktitle = {Proceedings of the 15th International Materials Symposium (IMSP’2014)}, pages = {441--450}, organization = {Pamukkale University (Denizli, Turkey)}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
Romano, M.; Hoinkes, C.; Ehrlich, I.; Höcherl, J.; Gebbeken, N. Influence of the impactor on the experimentally determined energy dissipation properties of fiber-reinforced plastics with hybrid layups under high velocity impact loads. Leichtbau Inproceedings Meran, C (Hrsg.): Proceedings of the 15th International Materials Symposium (IMSP’2014), S. 650–664, Pamukkale University (Denizli, Turkey) 2014. @inproceedings{Romano2014c, title = {Influence of the impactor on the experimentally determined energy dissipation properties of fiber-reinforced plastics with hybrid layups under high velocity impact loads. }, author = {M. Romano and C. Hoinkes and I. Ehrlich and J. Höcherl and N. Gebbeken}, editor = {C. Meran}, year = {2014}, date = {2014-10-01}, booktitle = {Proceedings of the 15th International Materials Symposium (IMSP’2014)}, pages = {650--664}, organization = {Pamukkale University (Denizli, Turkey)}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
Romano, M.; Micklitz, M.; Olbrich, F.; Bierl, R.; Ehrlich, I.; Gebbeken, N. Experimental investigation of damping properties of unidirectionally and fabric reinforced plastics by the free decay method. Leichtbau Inproceedings Meran, C (Hrsg.): Proceedings of the 15th International Materials Symposium (IMSP’2014), S. 665–679, Pamukkale University (Denizli, Turkey) 2014. @inproceedings{Romano2014d, title = {Experimental investigation of damping properties of unidirectionally and fabric reinforced plastics by the free decay method.}, author = {M. Romano and M. Micklitz and F. Olbrich and R. Bierl and I. Ehrlich and N. Gebbeken }, editor = {C. Meran}, year = {2014}, date = {2014-10-01}, booktitle = {Proceedings of the 15th International Materials Symposium (IMSP’2014)}, pages = {665--679}, organization = {Pamukkale University (Denizli, Turkey)}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
Nonn, A.; Brauer, H.; Großpietsch, D. Establishing the correlation between impact energies for different sized specimens using damage models Werkstoffsimulation Inproceedings 10th International Pipeline Conference 2014 (IPC 2014), Calgary, Canada, 2014. @inproceedings{Nonn2014b, title = {Establishing the correlation between impact energies for different sized specimens using damage models}, author = {A. Nonn and H. Brauer and D. Großpietsch}, doi = {10.1115/IPC2014-33164}, year = {2014}, date = {2014-09-29}, booktitle = {10th International Pipeline Conference 2014 (IPC 2014)}, address = {Calgary, Canada}, abstract = {The safety assessment of flawed pressurized pipes requires the knowledge of toughness properties which are usually provided in terms of impact energy from standard full-sized CVN notch specimens. For pipes with wall thickness less than 10mm different Charpy standards allow for the application of sub-sized specimens. However, it is still not fully clear how the impact energy from sub-sized specimens can be used to evaluate the fracture resistance of the pipes and how this energy correlates to the one from the full-sized specimen. Although different empirical correlations between sub-sized and full-sized specimens exist in the literature their validity is questionable since they are based on the results for older generation of steels. In the recent years the application of damage mechanics models has been promoted to assess the fracture behavior and deformation capacity of pipelines. The main advantage of these models can be found in their capability to link the damage evolution and the underlying stress/strain condition. In this paper damage mechanics approach is applied to describe fracture behavior of X65 pipeline material. Within the damage mechanics approach, Gurson-Tvergaard-Needleman (GTN) model is considered to be adequate for the simulation of ductile fracture. For brittle fracture, GTN model is extended by a propagation criterion which examines if the cleavage fracture stress is reached by the maximal principal stresses. The model parameters are calibrated and verified by means of load-displacement curves obtained from instrumented impact tests on different sized CVN specimens. This damage model is subsequently employed to simulate ductile-brittle transition behavior.}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } The safety assessment of flawed pressurized pipes requires the knowledge of toughness properties which are usually provided in terms of impact energy from standard full-sized CVN notch specimens. For pipes with wall thickness less than 10mm different Charpy standards allow for the application of sub-sized specimens. However, it is still not fully clear how the impact energy from sub-sized specimens can be used to evaluate the fracture resistance of the pipes and how this energy correlates to the one from the full-sized specimen. Although different empirical correlations between sub-sized and full-sized specimens exist in the literature their validity is questionable since they are based on the results for older generation of steels. In the recent years the application of damage mechanics models has been promoted to assess the fracture behavior and deformation capacity of pipelines. The main advantage of these models can be found in their capability to link the damage evolution and the underlying stress/strain condition. In this paper damage mechanics approach is applied to describe fracture behavior of X65 pipeline material. Within the damage mechanics approach, Gurson-Tvergaard-Needleman (GTN) model is considered to be adequate for the simulation of ductile fracture. For brittle fracture, GTN model is extended by a propagation criterion which examines if the cleavage fracture stress is reached by the maximal principal stresses. The model parameters are calibrated and verified by means of load-displacement curves obtained from instrumented impact tests on different sized CVN specimens. This damage model is subsequently employed to simulate ductile-brittle transition behavior. |
Nonn, A.; Erdelen-Peppler, M.; Wessel, W.; Niklasch, D.; Mahn, D. How to assure fracture-propagation control for seamless gas pipelines? Werkstoffsimulation Inproceedings 10th International Pipeline Conference 2014 (IPC 2014), Calgary, Canada, 2014. @inproceedings{Nonn2014c, title = {How to assure fracture-propagation control for seamless gas pipelines?}, author = {A. Nonn and M. Erdelen-Peppler and W. Wessel and D. Niklasch and D. Mahn}, doi = {10.1115/IPC2014-33169}, year = {2014}, date = {2014-09-29}, booktitle = {10th International Pipeline Conference 2014 (IPC 2014)}, address = {Calgary, Canada}, abstract = {Fracture propagation control in gas transmission gas pipelines belongs to the major design requirements for safe operation at high internal pressures. However, the current tests such as Drop-Weight-Tear Test (DWTT) and full-scale West-Jefferson (WJ) test reach the limits of their applicability with respect to transition temperature evaluation for seamless quenched and tempered small diameter pipes reflecting nowadays alloying concepts related to mechanical properties. Hereby, different geometry and material effects are evident which might lead to misinterpretation and unreliability of testing results. This paper aims to discuss open issues addressed in the literature and in own experimental findings with respect to reliability and transferability of testing methods, fracture parameters and their representativeness of seamless quenched and tempered pipeline behavior. By applying damage mechanics approach, it is possible to quantify the prevailing stress state and thus to understand the mechanisms controlling specific fracture appearance (ductile or brittle). Furthermore, studies were performed with objective to quantify the effect of different parameters (geometry, material and loading) on the fracture performance of the pipeline. The results from these investigations will serve as a basis for a safe pipeline design against propagating fracture.}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } Fracture propagation control in gas transmission gas pipelines belongs to the major design requirements for safe operation at high internal pressures. However, the current tests such as Drop-Weight-Tear Test (DWTT) and full-scale West-Jefferson (WJ) test reach the limits of their applicability with respect to transition temperature evaluation for seamless quenched and tempered small diameter pipes reflecting nowadays alloying concepts related to mechanical properties. Hereby, different geometry and material effects are evident which might lead to misinterpretation and unreliability of testing results. This paper aims to discuss open issues addressed in the literature and in own experimental findings with respect to reliability and transferability of testing methods, fracture parameters and their representativeness of seamless quenched and tempered pipeline behavior. By applying damage mechanics approach, it is possible to quantify the prevailing stress state and thus to understand the mechanisms controlling specific fracture appearance (ductile or brittle). Furthermore, studies were performed with objective to quantify the effect of different parameters (geometry, material and loading) on the fracture performance of the pipeline. The results from these investigations will serve as a basis for a safe pipeline design against propagating fracture. |
Karbasian, H.; Groß-Weege, J.; Nonn, A.; Zimmermann, S.; Kalwa, C. Assessment of collapse resistance of UOE pipes – comparison of full-scale and ring collapse tests Werkstoffsimulation Inproceedings 10th International Pipeline Conference 2014 (IPC 2014), Calgary, Canada, 2014. @inproceedings{Karbasian2014, title = {Assessment of collapse resistance of UOE pipes – comparison of full-scale and ring collapse tests}, author = {H. Karbasian and J. Groß-Weege and A. Nonn and S. Zimmermann and C. Kalwa}, year = {2014}, date = {2014-09-29}, booktitle = {10th International Pipeline Conference 2014 (IPC 2014)}, address = {Calgary, Canada}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
Baumer, A.; Kastenmeier, A.; Ehrlich, I. Investigation of Bolted Composite Joints with Different Reinforcement Elements at the Bolt Hole. Leichtbau Inproceedings Ziemann, O; Mottok, J; Pforr, J (Hrsg.): Applied Research Conference 2014 – ARC 2014, S. 255–258, Shaker-Verlag, 2014, ISBN: 978-3844028751. @inproceedings{Baumer2014, title = {Investigation of Bolted Composite Joints with Different Reinforcement Elements at the Bolt Hole.}, author = {A. Baumer and A. Kastenmeier and I. Ehrlich}, editor = {O. Ziemann and J. Mottok and J. Pforr}, isbn = {978-3844028751}, year = {2014}, date = {2014-07-15}, booktitle = {Applied Research Conference 2014 – ARC 2014}, pages = {255--258}, publisher = {Shaker-Verlag}, abstract = {Nowadays, there are hardly any structures without joints. On this occasion connections of composite materials with metallic components depict a particular challenge in the structural design. Bolted joints pose a significant weak point in the composite structure because of the strength step from composite to metal and the notch effect of the bolt hole. Nevertheless, such joints are often used in the vehicle and special vehicle construction, as these form-fitting joints can be implemented relatively simple and inexpensively. However, for highly stressed composite structures bolted joints show an insufficient strength. To improve the mechanical properties of the joint, there are various methods for reinforcing the bolt hole in the fiber reinforced plastic. The aim of this research project is to simulate different reinforced bolted joints on CRP (Carbon fiber Reinforced Plastic) pipe structures with the finite-element-method, manufacturing prototypes with the filament winding technique and then to examine experimentally in view of the mechanical properties, e.g. bearing and tensile strength. Before the tests are carried out on pipe structures, first of all the process of manufacturing and testing of reinforced bolted joints is developed for plane samples. These plane bolted joint samples of steel and CRP are tested for tension and bearing strength.}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } Nowadays, there are hardly any structures without joints. On this occasion connections of composite materials with metallic components depict a particular challenge in the structural design. Bolted joints pose a significant weak point in the composite structure because of the strength step from composite to metal and the notch effect of the bolt hole. Nevertheless, such joints are often used in the vehicle and special vehicle construction, as these form-fitting joints can be implemented relatively simple and inexpensively. However, for highly stressed composite structures bolted joints show an insufficient strength. To improve the mechanical properties of the joint, there are various methods for reinforcing the bolt hole in the fiber reinforced plastic. The aim of this research project is to simulate different reinforced bolted joints on CRP (Carbon fiber Reinforced Plastic) pipe structures with the finite-element-method, manufacturing prototypes with the filament winding technique and then to examine experimentally in view of the mechanical properties, e.g. bearing and tensile strength. Before the tests are carried out on pipe structures, first of all the process of manufacturing and testing of reinforced bolted joints is developed for plane samples. These plane bolted joint samples of steel and CRP are tested for tension and bearing strength. |
Romano, M.; Hoinkes, C.; Ehrlich, I.; Höcherl, J.; Gebbeken, N. Experimental investigation of fibre reinforced plastics with hybrid layups under high-velocity impact loads. Leichtbau Artikel Frattura ed Integrità Strutturale (Fracture and Structural Integrity), 8 (29), S. 385-398, 2014, ISSN: 1971-8993. @article{Romano2014, title = {Experimental investigation of fibre reinforced plastics with hybrid layups under high-velocity impact loads. }, author = {M. Romano and C. Hoinkes and I. Ehrlich and J. Höcherl and N. Gebbeken}, url = {http://www.fracturae.com/index.php/fis/article/view/IGF-ESIS.29.34 http://www.fracturae.com/index.php/fis/article/view/IGF-ESIS.29.34/1219 http://www.fracturae.com/index.php/fis/article/download/IGF-ESIS.29.34/1219 }, doi = {10.3221/IGF-ESIS.29.34 }, issn = {1971-8993}, year = {2014}, date = {2014-07-09}, journal = {Frattura ed Integrità Strutturale (Fracture and Structural Integrity)}, volume = {8}, number = {29}, pages = {385-398}, abstract = {This paper deals with experimental investigations concerning energy dissipation capacity of different kinds of reinforcement fibres in monolithic and hybrid layups under high-velocity impact loads. The investigated kinds of fibres are carbon, glass and basalt fibres. Therefore test panels, using the same thermoset resin, were built up and cured by autoclave processing. The fibre volume content of the test panels has been determined. Furthermore the influence of a separating layer at selected positions in the hybrid stacked panels was investigated. The results show the influence and the energy dissipation capacity of each single kind of fibre and the enhanced properties for the hybrid layups by hybrid stacking sequences and the use of a separating core material.}, keywords = {}, pubstate = {published}, tppubtype = {article} } This paper deals with experimental investigations concerning energy dissipation capacity of different kinds of reinforcement fibres in monolithic and hybrid layups under high-velocity impact loads. The investigated kinds of fibres are carbon, glass and basalt fibres. Therefore test panels, using the same thermoset resin, were built up and cured by autoclave processing. The fibre volume content of the test panels has been determined. Furthermore the influence of a separating layer at selected positions in the hybrid stacked panels was investigated. The results show the influence and the energy dissipation capacity of each single kind of fibre and the enhanced properties for the hybrid layups by hybrid stacking sequences and the use of a separating core material. |
Scheider, I.; Nonn, A.; Völling, A.; Mondry, A.; Kalwa, C. A damage mechanics based evaluation of dynamic fracture resistance in gas pipelines Werkstoffsimulation Inproceedings 20th European Conference on Fracture (ECF 20), Trondheim, Norway, 2014. @inproceedings{Scheider2014, title = {A damage mechanics based evaluation of dynamic fracture resistance in gas pipelines}, author = {I. Scheider and A. Nonn and A. Völling and A. Mondry and C. Kalwa}, year = {2014}, date = {2014-06-30}, booktitle = {20th European Conference on Fracture (ECF 20)}, address = {Trondheim, Norway}, abstract = {Investigation of running ductile fracture in gas transmission pipelines and the derivation of reliable crack arrest prediction methods belong to major topics in pipeline research. The yet available crack arrest criterion, known as the Battelle Two-Curve Method (BTCM), leads to reliable predictions up to grade X70 line pipe steels for which it has been validated. This includes specific limits in terms of mechanical properties, pressure and geometry. The application of this criterion to modern pipeline steels, i.e. especially grades X80 and beyond in combination with larger diameters and high pressure, has led to mispredictions of the BTCM. Hence, in order to ensure safe design of pipelines, new methods are required based on in depth knowledge and appropriate characterization of material resistance. This paper presents a procedure for the assessment of dynamic ductile fracture resistance based on combined experimental and numerical investigations. The procedure involves quasi-static and dynamic drop- weight tear testing (DWTT) on modified specimens with pre-fatigued crack for grades X65, X80 and X100 materials, and the application of cohesive zone (CZ) and Gurson-Tveergard-Needleman (GTN) models to describe ductile material damage. The damage model parameters are calibrated on basis of DWTT results and subsequently used to simulate dynamic crack propagation in a pipeline. The influence of material properties (strain hardening, toughness), pipe geometry, usage factor and decompression behaviour on ductile fracture propagation behaviour is studied and evaluated. The results will contribute to an enhanced understanding of major parameters controlling ductile fracture propagation and will help to establish a reliable procedure for safe design of new high-capacity pipelines with regard to crack arrest.}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } Investigation of running ductile fracture in gas transmission pipelines and the derivation of reliable crack arrest prediction methods belong to major topics in pipeline research. The yet available crack arrest criterion, known as the Battelle Two-Curve Method (BTCM), leads to reliable predictions up to grade X70 line pipe steels for which it has been validated. This includes specific limits in terms of mechanical properties, pressure and geometry. The application of this criterion to modern pipeline steels, i.e. especially grades X80 and beyond in combination with larger diameters and high pressure, has led to mispredictions of the BTCM. Hence, in order to ensure safe design of pipelines, new methods are required based on in depth knowledge and appropriate characterization of material resistance. This paper presents a procedure for the assessment of dynamic ductile fracture resistance based on combined experimental and numerical investigations. The procedure involves quasi-static and dynamic drop- weight tear testing (DWTT) on modified specimens with pre-fatigued crack for grades X65, X80 and X100 materials, and the application of cohesive zone (CZ) and Gurson-Tveergard-Needleman (GTN) models to describe ductile material damage. The damage model parameters are calibrated on basis of DWTT results and subsequently used to simulate dynamic crack propagation in a pipeline. The influence of material properties (strain hardening, toughness), pipe geometry, usage factor and decompression behaviour on ductile fracture propagation behaviour is studied and evaluated. The results will contribute to an enhanced understanding of major parameters controlling ductile fracture propagation and will help to establish a reliable procedure for safe design of new high-capacity pipelines with regard to crack arrest. |
Nonn, A.; Erdelen-Peppler, M.; Wessel, W.; Mahn, D. How reliable are the current testing procedures for the safety assurance against crack propagation in seamless gas pipelines Werkstoffsimulation Inproceedings The 33rd International Conference on Ocean, Offshore and Arctic Engineering 2014 (OMAE 2014), San-Francisco, USA, 2014. @inproceedings{Nonn2014, title = {How reliable are the current testing procedures for the safety assurance against crack propagation in seamless gas pipelines}, author = {A. Nonn and M. Erdelen-Peppler and W. Wessel and D. Mahn}, year = {2014}, date = {2014-06-08}, booktitle = {The 33rd International Conference on Ocean, Offshore and Arctic Engineering 2014 (OMAE 2014)}, address = {San-Francisco, USA}, abstract = {The worldwide growing energy demand with the exploration of new gas fields has promoted the development of high toughness seamless pipeline steels which should sustain the increasing demands resulting from the complex loading situations. One of the most important prerequisites for safe installation and operation of long distance gas transmission pipelines is the detailed knowledge and characterization of their fracture performance for specific applications. However, recent industry experience has revealed concerns related to the limitations and reliability of current test methods for brittle-to-ductile transition evaluation. Regarding the transition temperature evaluation, the critical issues involve Drop-Weight Tear Testing (DWTT) and full-scale West-Jefferson (WJ) test applied to the smaller pipes with diameter less than 500mm. The DWTT leads frequently to invalid results in terms of abnormal fracture appearance and inverse fracture occurrence. It is still not clear if this behavior is only owed to a testing effect, which material characteristics cause it and how far it reflects the full-scale behavior. Similar observations were made for the West-Jefferson tests, which could not be assessed in the standard manner either. Again, the question was towards testing effects and the behavior of the pipeline transporting gaseous media remains unanswered. Therefore, this paper aims at identifying open questions on basis of a literature study and own experimental results and showing possible ways forward in demonstrating safety in design against propagating fracture.}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } The worldwide growing energy demand with the exploration of new gas fields has promoted the development of high toughness seamless pipeline steels which should sustain the increasing demands resulting from the complex loading situations. One of the most important prerequisites for safe installation and operation of long distance gas transmission pipelines is the detailed knowledge and characterization of their fracture performance for specific applications. However, recent industry experience has revealed concerns related to the limitations and reliability of current test methods for brittle-to-ductile transition evaluation. Regarding the transition temperature evaluation, the critical issues involve Drop-Weight Tear Testing (DWTT) and full-scale West-Jefferson (WJ) test applied to the smaller pipes with diameter less than 500mm. The DWTT leads frequently to invalid results in terms of abnormal fracture appearance and inverse fracture occurrence. It is still not clear if this behavior is only owed to a testing effect, which material characteristics cause it and how far it reflects the full-scale behavior. Similar observations were made for the West-Jefferson tests, which could not be assessed in the standard manner either. Again, the question was towards testing effects and the behavior of the pipeline transporting gaseous media remains unanswered. Therefore, this paper aims at identifying open questions on basis of a literature study and own experimental results and showing possible ways forward in demonstrating safety in design against propagating fracture. |
Hoinkes, C.; Romano, M.; Ehrlich, I.; Höcherl, J.; Gebbeken, N. Investigation of fibre reinforced plastics with monolithic and hybrid stacking sequences under high-velocity impact loads. Leichtbau Inproceedings Ziemann, O; Mottok, J; Pforr, J (Hrsg.): Applied Research Conference 2014 – ARC 2014, Shaker-Verlag, 2014, ISBN: 978-3844028751. @inproceedings{Hoinkes2014, title = {Investigation of fibre reinforced plastics with monolithic and hybrid stacking sequences under high-velocity impact loads.}, author = {C. Hoinkes and M. Romano and I. Ehrlich and J. Höcherl and N. Gebbeken}, editor = {O. Ziemann and J. Mottok and J. Pforr}, isbn = {978-3844028751}, year = {2014}, date = {2014-06-01}, booktitle = {Applied Research Conference 2014 – ARC 2014}, publisher = {Shaker-Verlag}, abstract = {This study deals with the experimental investigation concerning the energy dissipation capacity of reinforcement fibres in monolithic and hybrid layups, with and without a separating layer, under high-velocity impact loads. The investigated kinds of fibres are carbon, glass and basalt fabrics in a twill 2/2 construction. The test panels have been impregnated with the same thermoset resin. Curing was done by autoclave processing. The resulting fibre volume content of the test panels have been determined both analytically by weighting and experimentally by chemical extraction and calcination. The impact loadwas applied by accelarating bearing balls with weighted propellant in a sabot. The measured values are the velocities of the bearing balls as the impactor before and after the penetration of the test panels. The results show the energy sissipation capacity of each single kind of fibre in the monolithic layups as well as the enhanced properties of the hybrid stacked layups.}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } This study deals with the experimental investigation concerning the energy dissipation capacity of reinforcement fibres in monolithic and hybrid layups, with and without a separating layer, under high-velocity impact loads. The investigated kinds of fibres are carbon, glass and basalt fabrics in a twill 2/2 construction. The test panels have been impregnated with the same thermoset resin. Curing was done by autoclave processing. The resulting fibre volume content of the test panels have been determined both analytically by weighting and experimentally by chemical extraction and calcination. The impact loadwas applied by accelarating bearing balls with weighted propellant in a sabot. The measured values are the velocities of the bearing balls as the impactor before and after the penetration of the test panels. The results show the energy sissipation capacity of each single kind of fibre in the monolithic layups as well as the enhanced properties of the hybrid stacked layups. |
Fritz, B.; Schmid, V.; Ehrlich, I. Analytical and numerical shear stress analysis of adhesive structural bonded joints under tension load. Leichtbau Inproceedings Ziemann, O; Mottok, J; Pforr, J (Hrsg.): Applied Research Conference 2014 – ARC 2014, S. 266–271, Ostbayerische Technische Hochschule Regensburg Shaker-Verlag, 2014, ISBN: 978-3844028751. @inproceedings{Fritz2014, title = {Analytical and numerical shear stress analysis of adhesive structural bonded joints under tension load.}, author = {B. Fritz and V. Schmid and I. Ehrlich}, editor = {O. Ziemann and J. Mottok and J. Pforr}, isbn = {978-3844028751}, year = {2014}, date = {2014-06-01}, booktitle = {Applied Research Conference 2014 – ARC 2014}, pages = {266--271}, publisher = {Shaker-Verlag}, organization = {Ostbayerische Technische Hochschule Regensburg}, abstract = {Force transmission is a critical zone in the construction of technical components, especially if these contain parts of fibre-reinforced plastics. The aim of this research is to improve and enhance the force transmission for a structural tubular adhesive bonded joint under axial load. Therefore a finite element model is being developed to compare different analytical calculation approaches. First investigations are based on a geometric simple single lap joint with an adhesive layer of epoxy resin. This model is examined analytical for several different calculation approaches, especially Volkerson and Goland & Reissner. The analytical results are compared to finite element analysis, particulary for shear stress distribution and the shear stress concentration factor. As a next step, the experience for the single lap joint is transferred for the calculation of tubular adhesive lap joints. Just as like for single lap joints, analytical approaches (Pugno) are investigated and the results compared to finite element analysis. Special interest is attended to disagreements and simplifying assumptions analytic models have to assume. In these cases finite element analysis (FEA) can deliver results that correlate more precise in analysis for actual shear stresses. In this paper special focus is placed on the shear stress distribution over length and width of the adhesive layer and the influence of the shear-stress-concentration factor. Furthermore, other parameters (geometry, stiffness, material) that have influence on the stress distribution are analyzed and evaluated in future investigations.}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } Force transmission is a critical zone in the construction of technical components, especially if these contain parts of fibre-reinforced plastics. The aim of this research is to improve and enhance the force transmission for a structural tubular adhesive bonded joint under axial load. Therefore a finite element model is being developed to compare different analytical calculation approaches. First investigations are based on a geometric simple single lap joint with an adhesive layer of epoxy resin. This model is examined analytical for several different calculation approaches, especially Volkerson and Goland & Reissner. The analytical results are compared to finite element analysis, particulary for shear stress distribution and the shear stress concentration factor. As a next step, the experience for the single lap joint is transferred for the calculation of tubular adhesive lap joints. Just as like for single lap joints, analytical approaches (Pugno) are investigated and the results compared to finite element analysis. Special interest is attended to disagreements and simplifying assumptions analytic models have to assume. In these cases finite element analysis (FEA) can deliver results that correlate more precise in analysis for actual shear stresses. In this paper special focus is placed on the shear stress distribution over length and width of the adhesive layer and the influence of the shear-stress-concentration factor. Furthermore, other parameters (geometry, stiffness, material) that have influence on the stress distribution are analyzed and evaluated in future investigations. |
Bruland, M.; Schmid, V.; Ehrlich, I. Analyzing and Testing of a Single Solution of Self-cutting Thread Inserts in Composites. Leichtbau Inproceedings Ziemann, O; Mottok, J; Pforr, J (Hrsg.): Applied Research Conference 2014 – ARC 2014, S. 286–288, Shaker-Verlag, 2014, ISBN: 978-3844028751. @inproceedings{Bruland2014, title = {Analyzing and Testing of a Single Solution of Self-cutting Thread Inserts in Composites.}, author = {M. Bruland and V. Schmid and I. Ehrlich}, editor = {O. Ziemann and J. Mottok and J. Pforr}, isbn = {978-3844028751}, year = {2014}, date = {2014-06-01}, booktitle = {Applied Research Conference 2014 – ARC 2014}, pages = {286--288}, publisher = {Shaker-Verlag}, abstract = {This paper gives a summary of the analysis and the testing of a single solution of self-cutting thread inserts in semi-manufactured composites for shape cutting. The used composites and inserts are for commercial use. As composites are not designed for drilling and withstanding internal compressive stress, there are some challenges involved when attempting to place an insert. }, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } This paper gives a summary of the analysis and the testing of a single solution of self-cutting thread inserts in semi-manufactured composites for shape cutting. The used composites and inserts are for commercial use. As composites are not designed for drilling and withstanding internal compressive stress, there are some challenges involved when attempting to place an insert. |
Niedernhuber, M.; Ehrlich, I.; Holtmannspötter, J. Fiber-Oriented Repair of Fiber Reinforced Plastics: Investigations on Tensile Specimens Leichtbau Inproceedings Ziemann, O; Mottok, J; Pforr, J (Hrsg.): Applied Research Conference 2014 – ARC 2014, S. 298–302, Ostbayerische Technische Hochschule Regensburg Shaker-Verlag, 2014, ISBN: 978-3844028751. @inproceedings{Niedernhuber2014, title = {Fiber-Oriented Repair of Fiber Reinforced Plastics: Investigations on Tensile Specimens}, author = {M. Niedernhuber and I. Ehrlich and J. Holtmannspötter}, editor = {O. Ziemann and J. Mottok and J. Pforr}, isbn = {978-3844028751}, year = {2014}, date = {2014-06-01}, booktitle = {Applied Research Conference 2014 – ARC 2014}, pages = {298--302}, publisher = {Shaker-Verlag}, organization = {Ostbayerische Technische Hochschule Regensburg}, abstract = {To minimize the repair area for fiber reinforced plastics (FRP), a new scarfing method is under investigation. For unidirectional plies, the idea is to perform a stepped scarf in fiber direction only. In theory, the repair area can be reduced up to 50 percent. Repair geometries generated with this method display varying overlap lengths in specific directions. With tensile tests of specimens according to german standards, a first comparison of mechanical values and joint strength between fiber-oriented scarfs and traditionally stepped scarfs in carbon fiber reinforced plastics (CFRP) was carried out. Mechanical values of the joint specimens showed only minor differences to intact laminates. The tensile strength of the stepped scarf and fiber-oriented scarf joints were around 50 % relative to the intact laminate. Our results show that the shorter overlap lengths in the plies of the fiber-oriented joints did not lead to the failure of specimen, instead, the butt joint on the outer surfaces of the specimens seem to be the initial point of failure.}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } To minimize the repair area for fiber reinforced plastics (FRP), a new scarfing method is under investigation. For unidirectional plies, the idea is to perform a stepped scarf in fiber direction only. In theory, the repair area can be reduced up to 50 percent. Repair geometries generated with this method display varying overlap lengths in specific directions. With tensile tests of specimens according to german standards, a first comparison of mechanical values and joint strength between fiber-oriented scarfs and traditionally stepped scarfs in carbon fiber reinforced plastics (CFRP) was carried out. Mechanical values of the joint specimens showed only minor differences to intact laminates. The tensile strength of the stepped scarf and fiber-oriented scarf joints were around 50 % relative to the intact laminate. Our results show that the shorter overlap lengths in the plies of the fiber-oriented joints did not lead to the failure of specimen, instead, the butt joint on the outer surfaces of the specimens seem to be the initial point of failure. |
Micklitz, M.; Romano, M.; Ehrlich, I.; Gebbeken, N. The influence of ondulations in fabric reinforced layers on the damping properties of fibre-reinforced plastics Leichtbau Inproceedings Ziemann, O; Mottok, J; Pforr, J (Hrsg.): Applied Research Conference 2014 – ARC 2014, S. 306–310, Ostbayerische Technische Hochschule Regensburg Shaker-Verlag, 2014, ISBN: 978-3844028751. @inproceedings{Micklitz2014, title = {The influence of ondulations in fabric reinforced layers on the damping properties of fibre-reinforced plastics}, author = {M. Micklitz and M. Romano and I. Ehrlich and N. Gebbeken}, editor = {O. Ziemann and J. Mottok and J. Pforr}, isbn = {978-3844028751}, year = {2014}, date = {2014-06-01}, booktitle = {Applied Research Conference 2014 – ARC 2014}, pages = {306--310}, publisher = {Shaker-Verlag}, organization = {Ostbayerische Technische Hochschule Regensburg}, abstract = {Ondulations in fabric-reinforced single layers are caused by alternatingly crossing of warp and fill yarns. In order to determine the influence of the ondulations in fabrics on the damping properties of fibre-reinforced plastics, the structural dynamic properties of fabric-reinforced and unidirectionally reinforced Plastics are investigated. Therefore, vibration experiments are carried outby the free-decay method. Fabric-reinforced and unidriectionally reinforced flat beamlike specimens were cut out of test panels by waterjet cutting. The test panels were impregnated via pre-impregnation in case of the fabric-reinforced material, and filament winding in case of the unidirectionally reinforced material. In both cases the same thermoset resin has been used, in order to ensure maximum comparability between the different specimens. In order to additionally obtain comparable fibre volume contents of approx. 60 %, curing was done by autoclave processing. In detail the structural mechanical investigations are carried out by the free decay of fixed-free specimens after reproducible displacement excitations. The vibrating structure has been measured by a laser scanning vibrometer PSV 400 from Polytec. The evaluation of the results for the specimen with unidirectional and fabric reinforcement yields enhanced damping properties.}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } Ondulations in fabric-reinforced single layers are caused by alternatingly crossing of warp and fill yarns. In order to determine the influence of the ondulations in fabrics on the damping properties of fibre-reinforced plastics, the structural dynamic properties of fabric-reinforced and unidirectionally reinforced Plastics are investigated. Therefore, vibration experiments are carried outby the free-decay method. Fabric-reinforced and unidriectionally reinforced flat beamlike specimens were cut out of test panels by waterjet cutting. The test panels were impregnated via pre-impregnation in case of the fabric-reinforced material, and filament winding in case of the unidirectionally reinforced material. In both cases the same thermoset resin has been used, in order to ensure maximum comparability between the different specimens. In order to additionally obtain comparable fibre volume contents of approx. 60 %, curing was done by autoclave processing. In detail the structural mechanical investigations are carried out by the free decay of fixed-free specimens after reproducible displacement excitations. The vibrating structure has been measured by a laser scanning vibrometer PSV 400 from Polytec. The evaluation of the results for the specimen with unidirectional and fabric reinforcement yields enhanced damping properties. |
Gomez, D. Ibanez; Kastenmeier, A.; Ehrlich, I. Development and construction of a winding machine for the production of composite tubes. Leichtbau Inproceedings Ziemann, O; Mottok, J; Pforr, J (Hrsg.): Applied Research Conference 2014 – ARC 2014, S. 315–318, Ostbayerische Technische Hochschule Regensburg Shaker-Verlag, 2014, ISBN: 978-3844028751. @inproceedings{IbanezGomez2014, title = {Development and construction of a winding machine for the production of composite tubes.}, author = {D. Ibanez Gomez and A. Kastenmeier and I. Ehrlich}, editor = {O. Ziemann and J. Mottok and J. Pforr}, isbn = {978-3844028751}, year = {2014}, date = {2014-06-01}, booktitle = {Applied Research Conference 2014 – ARC 2014}, pages = {315--318}, publisher = {Shaker-Verlag}, organization = {Ostbayerische Technische Hochschule Regensburg}, abstract = {The project is about the development and construction of a filament winding machine. The aim of the project is that the laboratory of composite technology of the Ostbayerische Technische Hochschule Regensburg is able to produce composite tube specimens in laboratory scale, so that different tube geometries can be manufactured. With a own machine the lab is able to produce many different specimens. Furthermore, the lab is able to test in additional machines different force transmissions or respectively connections of the tubes with metal flanges. Presently there is no possibility for the lab to produce tube specimens. In fact the winding technology already exists on the market, but for the lab it is important to have a machine with the right properties. For example the functions of the machine must be adjusted to the specifications of the tube specimens. The machine is constructed of four modules: a pre-load-, an impregnation-, a slide- and a mandrel-module. The function of the pre-load module is to aplly a defined load to the rovings. In the impregnation module the rovings are wetted with resin. The combination of the slide- and mandrel-module enables the define depositting of the rovings on the mandrel. The VDI guideline 2221 is used to develop the winding machine. In this guideline the approach of the development is defined. The first step is to define the requirements. After that a theoretical solution has to be found and this solution has to be elaborated. Finally, the concept has to be optimized for the assembly.}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } The project is about the development and construction of a filament winding machine. The aim of the project is that the laboratory of composite technology of the Ostbayerische Technische Hochschule Regensburg is able to produce composite tube specimens in laboratory scale, so that different tube geometries can be manufactured. With a own machine the lab is able to produce many different specimens. Furthermore, the lab is able to test in additional machines different force transmissions or respectively connections of the tubes with metal flanges. Presently there is no possibility for the lab to produce tube specimens. In fact the winding technology already exists on the market, but for the lab it is important to have a machine with the right properties. For example the functions of the machine must be adjusted to the specifications of the tube specimens. The machine is constructed of four modules: a pre-load-, an impregnation-, a slide- and a mandrel-module. The function of the pre-load module is to aplly a defined load to the rovings. In the impregnation module the rovings are wetted with resin. The combination of the slide- and mandrel-module enables the define depositting of the rovings on the mandrel. The VDI guideline 2221 is used to develop the winding machine. In this guideline the approach of the development is defined. The first step is to define the requirements. After that a theoretical solution has to be found and this solution has to be elaborated. Finally, the concept has to be optimized for the assembly. |
Romano, M.; Hoinkes, C.; Ehrlich, I.; Höcherl, J.; Gebbeken, N. Experimental investigation of energy dissipation properties of fibre reinforced plastics with hybrid layups under high-velocity impact loads. Leichtbau Artikel Journal of Achievements in Materials and Manufacturing Engineering (JAMME), 64 (1), S. 14–20, 2014. @article{Romano2014b, title = {Experimental investigation of energy dissipation properties of fibre reinforced plastics with hybrid layups under high-velocity impact loads.}, author = {M. Romano and C. Hoinkes and I. Ehrlich and J. Höcherl and N. Gebbeken}, url = {http://jamme.acmsse.h2.pl/vol64_1/6411.pdf}, year = {2014}, date = {2014-05-01}, journal = {Journal of Achievements in Materials and Manufacturing Engineering (JAMME)}, volume = {64}, number = {1}, pages = {14--20}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Valentino, P.; Sgambitterra, E.; Furgiuele, F.; Romano, M.; Ehrlich, I.; Gebbeken, N. Mechanical characterization of basalt woven fabric composites: numerical and experimental investigation. Leichtbau Artikel Frattura ed Integrità Strutturale (Fracture and Structural Integrity), 8 (28), S. 1-11, 2014, ISSN: 1971-8993. @article{Valentino2014, title = {Mechanical characterization of basalt woven fabric composites: numerical and experimental investigation.}, author = {P. Valentino and E. Sgambitterra and F. Furgiuele and M. Romano and I. Ehrlich and N. Gebbeken}, url = {http://www.gruppofrattura.it/ors/index.php/fis/article/view/1229 http://www.gruppofrattura.it/ors/index.php/fis/article/view/1229/1182 http://www.gruppofrattura.it/ors/index.php/fis/article/download/1229/1182 }, doi = {10.3221/IGF-ESIS.28.01}, issn = {1971-8993}, year = {2014}, date = {2014-04-08}, journal = {Frattura ed Integrità Strutturale (Fracture and Structural Integrity)}, volume = {8}, number = {28}, pages = {1-11}, abstract = {Basalt fabric composite, with different twill wave reinforcements, i.e. twill 2/2 and twill 1/3, have been studied in this work by means of experimental tests and numerical finite element (FE) simulations. As fabric reinforcements show repeating undulations of warp and fill yarn, simple mixtures law cannot be applied. As a consequence, the mesoscopic scale, lying between the microscopic and the macroscopic one, has to be taken into account to mechanically characterize a fabric reinforced composite. The aim of this work is to evaluate the stiffness of a fabric reinforced composite in warp and fill direction. In particular a numerical FE model, assuming elliptical sections and sinusoidal shape of the yarns, has been implemented and experimental tests have been carried out in order to validate the proposed model. Finally, the strength and the failure modes of the composite material, for each analysed structure and textile orientation, have been experimentally investigated.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Basalt fabric composite, with different twill wave reinforcements, i.e. twill 2/2 and twill 1/3, have been studied in this work by means of experimental tests and numerical finite element (FE) simulations. As fabric reinforcements show repeating undulations of warp and fill yarn, simple mixtures law cannot be applied. As a consequence, the mesoscopic scale, lying between the microscopic and the macroscopic one, has to be taken into account to mechanically characterize a fabric reinforced composite. The aim of this work is to evaluate the stiffness of a fabric reinforced composite in warp and fill direction. In particular a numerical FE model, assuming elliptical sections and sinusoidal shape of the yarns, has been implemented and experimental tests have been carried out in order to validate the proposed model. Finally, the strength and the failure modes of the composite material, for each analysed structure and textile orientation, have been experimentally investigated. |
Cerrone, A.; Wawrzynek, P.; Nonn, A.; Paulino, G. H.; Ingraffea, A. Implementation and verification of the Park–Paulino–Roesler cohesive zone model in 3D Werkstoffsimulation Artikel Engineering Fracture Mechanics, 120 , S. 26 - 42, 2014, ISSN: 0013-7944. @article{Cerrone2014b, title = {Implementation and verification of the Park–Paulino–Roesler cohesive zone model in 3D}, author = {A. Cerrone and P. Wawrzynek and A. Nonn and G. H. Paulino and A. Ingraffea}, url = {http://www.sciencedirect.com/science/article/pii/S0013794414000770}, doi = {https://doi.org/10.1016/j.engfracmech.2014.03.010}, issn = {0013-7944}, year = {2014}, date = {2014-01-01}, journal = {Engineering Fracture Mechanics}, volume = {120}, pages = {26 - 42}, abstract = {The Park–Paulino–Roesler (PPR) potential-based model is a cohesive constitutive model formulated to be consistent under a high degree of mode-mixity. Herein, the PPR’s generalization to three-dimensions is detailed, its implementation in a finite element framework is discussed, and its use in single-core and high performance computing (HPC) applications is demonstrated. The PPR model is shown to be an effective constitutive model to account for crack nucleation and propagation in a variety of applications including adhesives, composites, linepipe steel, and microstructures.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The Park–Paulino–Roesler (PPR) potential-based model is a cohesive constitutive model formulated to be consistent under a high degree of mode-mixity. Herein, the PPR’s generalization to three-dimensions is detailed, its implementation in a finite element framework is discussed, and its use in single-core and high performance computing (HPC) applications is demonstrated. The PPR model is shown to be an effective constitutive model to account for crack nucleation and propagation in a variety of applications including adhesives, composites, linepipe steel, and microstructures. |
Valentino, P.; Romano, M.; Ehrlich, I.; Furgiuele, F.; Gebbeken, N. Mechanische Charakterisierung von basaltfaser-verstärkten Kunststoffen mit Gewebeverstärkung – Numerische und experimentelle Untersuchungen. Leichtbau Forschungsbericht Ostbayerische Hochschule Regensburg inixmedia GmbH Marketing & Medienberatung, Forschungsbericht 2013, 2014. @techreport{Valentino2014b, title = {Mechanische Charakterisierung von basaltfaser-verstärkten Kunststoffen mit Gewebeverstärkung – Numerische und experimentelle Untersuchungen.}, author = {P. Valentino and M. Romano and I. Ehrlich and F. Furgiuele and N. Gebbeken}, editor = {Ostbayerische Technische Hochschule}, year = {2014}, date = {2014-01-01}, address = {inixmedia GmbH Marketing & Medienberatung}, institution = {Ostbayerische Hochschule Regensburg}, abstract = {This paper describes the results of tensile tests and finite element (FE) calculations with representative volume elements (RVEs) of basalt fibre reinforced plastic with two different types of fabric reinforcements. As fabric reinforcements show repeating ondulations of warp and fill yarn, simple mixtures laws reach their limits. The aim of this work is to determine the stiffness of a fabric reinforced composite in warp and fill direction with numerical investigations. The tensile tests and the FE-calculations have been carried out for two different types of basalt fabrics, namely twill 2/2 and twill 1/3. The comparison between the experimental data and the results of the FE-calculations are provided in order to support the validity of the proposed model.}, type = {Forschungsbericht 2013}, keywords = {}, pubstate = {published}, tppubtype = {techreport} } This paper describes the results of tensile tests and finite element (FE) calculations with representative volume elements (RVEs) of basalt fibre reinforced plastic with two different types of fabric reinforcements. As fabric reinforcements show repeating ondulations of warp and fill yarn, simple mixtures laws reach their limits. The aim of this work is to determine the stiffness of a fabric reinforced composite in warp and fill direction with numerical investigations. The tensile tests and the FE-calculations have been carried out for two different types of basalt fabrics, namely twill 2/2 and twill 1/3. The comparison between the experimental data and the results of the FE-calculations are provided in order to support the validity of the proposed model. |
Eisenried, M.; Romano, M.; Jungbauer, B.; Ehrlich, I.; Gebbeken, N. Herstellung von unidirektional verstärkten Prepregs im Labormaßstab – Einfluss von Fertigungsparametern auf die Materialqualität. Leichtbau Forschungsbericht Ostbayerische Hochschule Regensburg inixmedia GmbH Marketing & Medienberatung, Forschungsbericht 2013, 2014. @techreport{Eisenried2014, title = {Herstellung von unidirektional verstärkten Prepregs im Labormaßstab – Einfluss von Fertigungsparametern auf die Materialqualität.}, author = {M. Eisenried and M. Romano and B. Jungbauer and I. Ehrlich and N. Gebbeken}, editor = {Ostbayerische Technische Hochschule}, year = {2014}, date = {2014-01-01}, address = {inixmedia GmbH Marketing & Medienberatung}, institution = {Ostbayerische Hochschule Regensburg}, abstract = {A prepreg production device in laboratory scale is used to develop the production process of unidirectionally reinforced prepregs. The aim of the prepreg production machine is to impregnate different types of reinforcement fibers with an arbitrarily selectable thermoset matrix system that completely satisfies the requirements for autoclave processing. To identify the parameters of the production process and investigate its sensitivity on the quality of the semi-finished product, experimental investigations regarding fiber volume content and resin flow while curing are carried out with specimens out of test panels cured in autoclave processing. The investigated parameter is the width of the wiping gap and its effects on fiber volume content and resin flow. The parameter clearly affects both properties so that a proper impregnation and curing process can be achieved by optimizing the parameter to desired values.}, type = {Forschungsbericht 2013}, keywords = {}, pubstate = {published}, tppubtype = {techreport} } A prepreg production device in laboratory scale is used to develop the production process of unidirectionally reinforced prepregs. The aim of the prepreg production machine is to impregnate different types of reinforcement fibers with an arbitrarily selectable thermoset matrix system that completely satisfies the requirements for autoclave processing. To identify the parameters of the production process and investigate its sensitivity on the quality of the semi-finished product, experimental investigations regarding fiber volume content and resin flow while curing are carried out with specimens out of test panels cured in autoclave processing. The investigated parameter is the width of the wiping gap and its effects on fiber volume content and resin flow. The parameter clearly affects both properties so that a proper impregnation and curing process can be achieved by optimizing the parameter to desired values. |
Putzer, M.; Rasmussen, J.; Ehrlich, I.; Gebbeken, N.; Dendorfer, S. Muskuloskelettale Simulation zur Untersuchung des Einflusses geometrischer Parameter der Wirbelkörper auf die Belastung der Lendenwirbelsäule. Leichtbau Forschungsbericht Ostbayerische Hochschule Regensburg inixmedia GmbH Marketing & Medienberatung, Forschungsbericht 2013, 2014. @techreport{Putzer2014, title = {Muskuloskelettale Simulation zur Untersuchung des Einflusses geometrischer Parameter der Wirbelkörper auf die Belastung der Lendenwirbelsäule.}, author = {M. Putzer and J. Rasmussen and I. Ehrlich and N. Gebbeken and S. Dendorfer}, editor = {Ostbayerische Technische Hochschule}, year = {2014}, date = {2014-01-01}, address = {inixmedia GmbH Marketing & Medienberatung}, institution = {Ostbayerische Hochschule Regensburg}, abstract = {Zur Simulation von patientenspezifischen Belastungen in der Lendenwirbelsäule werden muskuloskelettale Modelle mit patientenspezifischer Geometrie verwendet. Diese Daten besitzen allerdings eine inhärente Ungenauigkeit. Diese Studie untersuchte den Einfluss definierter geometrischer Parameter auf die Lasten in der Lendenwirbelsäule anhand eines parametri-sierten muskuloskelettalen Modells in vier verschiedenen Körperhaltungen: aufrecht stehend, vorgebeugt, zur Seite gedreht und zur Seite geneigt. Variiert wurden die Abmessungen des Wirbelkörpers, des Wirbelbogens und der Dornfortsätze sowie die Orientierung der Facettengelenke und die Krümmung der Lendenwirbelsäule. Anschließend wurden die Parameter mit den größten Einflüssen in weiteren Simulationen kombiniert. Die Änderung der Last zwischen L4 und L5 wurde als Ziel der Untersuchung festgelegt. Die größten Lastunterschiede ergaben sich durch die Änderung der Wirbelkörperhöhe, der Band-scheibenhöhe, der Wirbelkörpertiefe und der Krümmung der Lendenwirbelsäule.}, type = {Forschungsbericht 2013}, keywords = {}, pubstate = {published}, tppubtype = {techreport} } Zur Simulation von patientenspezifischen Belastungen in der Lendenwirbelsäule werden muskuloskelettale Modelle mit patientenspezifischer Geometrie verwendet. Diese Daten besitzen allerdings eine inhärente Ungenauigkeit. Diese Studie untersuchte den Einfluss definierter geometrischer Parameter auf die Lasten in der Lendenwirbelsäule anhand eines parametri-sierten muskuloskelettalen Modells in vier verschiedenen Körperhaltungen: aufrecht stehend, vorgebeugt, zur Seite gedreht und zur Seite geneigt. Variiert wurden die Abmessungen des Wirbelkörpers, des Wirbelbogens und der Dornfortsätze sowie die Orientierung der Facettengelenke und die Krümmung der Lendenwirbelsäule. Anschließend wurden die Parameter mit den größten Einflüssen in weiteren Simulationen kombiniert. Die Änderung der Last zwischen L4 und L5 wurde als Ziel der Untersuchung festgelegt. Die größten Lastunterschiede ergaben sich durch die Änderung der Wirbelkörperhöhe, der Band-scheibenhöhe, der Wirbelkörpertiefe und der Krümmung der Lendenwirbelsäule. |
2013 |
Eisenried, M.; Romano, M.; Jungbauer, B.; Ehrlich, I.; Gebbeken, N. Influence of parameters of the production process on the material quality of unidirectionally reinforced prepregs. Leichtbau Inproceedings Ziemann, O; Bogner, W; Mottok, J (Hrsg.): Applied Research Conference 2013 – ARC 2013, S. 70–75, Ostbayerische Technische Hochschule Regensburg Shaker-Verlag, 2013, ISBN: 978-3844022742. @inproceedings{Eisenried2013, title = {Influence of parameters of the production process on the material quality of unidirectionally reinforced prepregs.}, author = {M. Eisenried and M. Romano and B. Jungbauer and I. Ehrlich and N. Gebbeken}, editor = {O. Ziemann and W. Bogner and J. Mottok}, isbn = {978-3844022742}, year = {2013}, date = {2013-10-17}, booktitle = {Applied Research Conference 2013 – ARC 2013}, pages = {70--75}, publisher = {Shaker-Verlag}, organization = {Ostbayerische Technische Hochschule Regensburg}, abstract = {A prepreg production device in laboratory scale is used to develop the production process of unidirectionally reinforced prepregs. The aim of the prepreg production machine is to impregnate different types of reinforcement fibres with an arbitrarily selectable thermoset matrix system that completely satisfies the requirements for autoclave processing. As the prepreg production device is designed and built up modulary every module corresponds to one step in the process. To identify the parameters of the production process and investigate its sensitivity on the quality of the semi-finished product, experimental investigations regarding fiber volume content, resin flow while curing and geometric properties are carried out with specimens out of test panels cured in autoclave processing. The investigated parameter ist the width of the wiping gap and its effects on fiber volume content and resin flow. Both mechanical properties are determined according to german standards. The parameter clearly affects both properties so that a proper impregnation and curing process can be achieved by optimizing the parameter to desired values.}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } A prepreg production device in laboratory scale is used to develop the production process of unidirectionally reinforced prepregs. The aim of the prepreg production machine is to impregnate different types of reinforcement fibres with an arbitrarily selectable thermoset matrix system that completely satisfies the requirements for autoclave processing. As the prepreg production device is designed and built up modulary every module corresponds to one step in the process. To identify the parameters of the production process and investigate its sensitivity on the quality of the semi-finished product, experimental investigations regarding fiber volume content, resin flow while curing and geometric properties are carried out with specimens out of test panels cured in autoclave processing. The investigated parameter ist the width of the wiping gap and its effects on fiber volume content and resin flow. Both mechanical properties are determined according to german standards. The parameter clearly affects both properties so that a proper impregnation and curing process can be achieved by optimizing the parameter to desired values. |
Nonn, A.; Cerrone, A.; Stallybrass, C.; Meuser, H. Microstructure-based modeling of high-strength linepipe steels Werkstoffsimulation Inproceedings The 6th Pipeline Technology Conference (2013), Ostend, Belgium, 2013. @inproceedings{Nonn2013, title = {Microstructure-based modeling of high-strength linepipe steels}, author = {A. Nonn and A. Cerrone and C. Stallybrass and H. Meuser}, year = {2013}, date = {2013-10-07}, booktitle = {The 6th Pipeline Technology Conference (2013)}, address = {Ostend, Belgium}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
Nonn, A.; Kalwa, C. Analysis of dynamic ductile fracture propagation in pipeline steels: a damage mechanics approach Werkstoffsimulation Inproceedings The 6th Pipeline Technology Conference (2013), Ostend, Belgium, 2013. @inproceedings{Nonn2013b, title = {Analysis of dynamic ductile fracture propagation in pipeline steels: a damage mechanics approach}, author = {A. Nonn and C. Kalwa}, year = {2013}, date = {2013-10-07}, booktitle = {The 6th Pipeline Technology Conference (2013)}, address = {Ostend, Belgium}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
Nonn, A.; Kalwa, C. Application of probabilistic fracture mechanics for safety assessment of longitudinally welded linepipes Werkstoffsimulation Inproceedings The 6th Pipeline Technology Conference (2013), Ostend, Belgium, 2013. @inproceedings{Nonn2013c, title = {Application of probabilistic fracture mechanics for safety assessment of longitudinally welded linepipes}, author = {A. Nonn and C. Kalwa}, year = {2013}, date = {2013-10-07}, booktitle = {The 6th Pipeline Technology Conference (2013)}, address = {Ostend, Belgium}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
Valentino, P.; Romano, M.; Ehrlich, I.; Furgiuele, F.; Gebbeken, N. Mechanical characterization of basalt fibre reinforced plastic with different fabric reinforcements – Tensile tests and FE-calculations with representative volume elements (RVEs). Leichtbau Inproceedings Iacovello, F; Risitano, G; Susmel, L (Hrsg.): Acta Fracturae – XXll Convegno Nazionale IGF (Italiano Gruppo Frattura), Roma, 2013, ISBN: 978-88-95940-47-2. @inproceedings{Valentino2013, title = {Mechanical characterization of basalt fibre reinforced plastic with different fabric reinforcements – Tensile tests and FE-calculations with representative volume elements (RVEs). }, author = {P. Valentino and M. Romano and I. Ehrlich and F. Furgiuele and N. Gebbeken}, editor = {F. Iacovello and G. Risitano and L. Susmel}, url = {http://www.gruppofrattura.it/pdf/convegni/22/IGFXXII/index.html#/242/}, isbn = {978-88-95940-47-2}, year = {2013}, date = {2013-07-03}, booktitle = {Acta Fracturae – XXll Convegno Nazionale IGF (Italiano Gruppo Frattura)}, address = {Roma}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
Nonn, A.; Wessel, W.; Schmidt, T. Application of finite element analysis for assessment of fracture behavior of modern high toughness seamless pipeline steels Werkstoffsimulation Inproceedings The 23rd International Society of Offshore and Polar Engineering 2013 (ISOPE 2013), Anchorage, USA, 2013. @inproceedings{Nonn2013d, title = {Application of finite element analysis for assessment of fracture behavior of modern high toughness seamless pipeline steels}, author = {A. Nonn and W. Wessel and T. Schmidt}, year = {2013}, date = {2013-06-30}, booktitle = {The 23rd International Society of Offshore and Polar Engineering 2013 (ISOPE 2013)}, address = {Anchorage, USA}, abstract = {Fracture behavior of seamless pipeline material X65Q acc. to API 5L has been studied both experimentally and numerically at different loading conditions (quasi-static vs. dynamic) and temperatures. The recent findings have shown difficulties in applying well established methods for determination of transition behavior or prediction of ductile crack arrest for the new generation of high-toughness steels. The irregular fracture performance (e.g. so-called "abnormal inverse fracture" appearance, significant scattering in ductile-to-brittle-transition-temperature region, etc.) suggests that the influence of pipe dimensions, loading parameters, crack initiation resistance as well as testing procedure on the fracture behavior has been neither understood nor properly described. This work aims to shed light on these questions regarding the applicability of conventional methods and to better illuminate most relevant parameters affecting fracture behavior of high toughness steels. To achieve this goal, experimental data basis for analysis of fracture behavior in transition and upper shelf regime has been established by conducting quasi-static fracture mechanics tests and dynamic tests on Battelle Drop Weight Tear (BDWT or DWT) specimens at different temperatures. The evaluation of obtained test results in upper shelf has been additionally complemented by numerical simulation of damage behavior. The results highlight the influence of stress conditions on fracture behavior with reference to pipe dimensions and loading conditions and, subsequently, may be used as a basis for revision of existing design methods.}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } Fracture behavior of seamless pipeline material X65Q acc. to API 5L has been studied both experimentally and numerically at different loading conditions (quasi-static vs. dynamic) and temperatures. The recent findings have shown difficulties in applying well established methods for determination of transition behavior or prediction of ductile crack arrest for the new generation of high-toughness steels. The irregular fracture performance (e.g. so-called "abnormal inverse fracture" appearance, significant scattering in ductile-to-brittle-transition-temperature region, etc.) suggests that the influence of pipe dimensions, loading parameters, crack initiation resistance as well as testing procedure on the fracture behavior has been neither understood nor properly described. This work aims to shed light on these questions regarding the applicability of conventional methods and to better illuminate most relevant parameters affecting fracture behavior of high toughness steels. To achieve this goal, experimental data basis for analysis of fracture behavior in transition and upper shelf regime has been established by conducting quasi-static fracture mechanics tests and dynamic tests on Battelle Drop Weight Tear (BDWT or DWT) specimens at different temperatures. The evaluation of obtained test results in upper shelf has been additionally complemented by numerical simulation of damage behavior. The results highlight the influence of stress conditions on fracture behavior with reference to pipe dimensions and loading conditions and, subsequently, may be used as a basis for revision of existing design methods. |
Nonn, A.; Kalwa, C. Application of damage mechanics approach for crack propagation in pipeline Werkstoffsimulation Inproceedings 19th Biennial JTM on Pipeline Research, Sidney, Australia, 2013. @inproceedings{Nonn2013e, title = {Application of damage mechanics approach for crack propagation in pipeline}, author = {A. Nonn and C. Kalwa}, year = {2013}, date = {2013-04-29}, booktitle = {19th Biennial JTM on Pipeline Research}, address = {Sidney, Australia}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
Völling, A.; Nonn, A.; Scheider, I. Anwendung des Kohäsivzonenmodells zur Abbildung von duktilem dynamischen Rissfortschritt in Gasfernleitungen Werkstoffsimulation Inproceedings 45. Tagung des AK Bruch, DVM Berichtsband 245, S. 253-262, Berlin, Germany, 2013. @inproceedings{Völling2013, title = {Anwendung des Kohäsivzonenmodells zur Abbildung von duktilem dynamischen Rissfortschritt in Gasfernleitungen}, author = {A. Völling and A. Nonn and I. Scheider}, year = {2013}, date = {2013-02-19}, booktitle = {45. Tagung des AK Bruch, DVM Berichtsband 245}, pages = {253-262}, address = {Berlin, Germany}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
Kofiani, K.; Nonn, A.; Wierzbicki, T. New calibration method for high and low triaxiality and validation on SENT specimens of API X70 Werkstoffsimulation Artikel International Journal of Pressure Vessels and Piping, 111-112 , S. 187 - 201, 2013, ISSN: 0308-0161. @article{Kofiani2013b, title = {New calibration method for high and low triaxiality and validation on SENT specimens of API X70}, author = {K. Kofiani and A. Nonn and T. Wierzbicki}, url = {http://www.sciencedirect.com/science/article/pii/S0308016113001130}, doi = {https://doi.org/10.1016/j.ijpvp.2013.07.004}, issn = {0308-0161}, year = {2013}, date = {2013-01-01}, journal = {International Journal of Pressure Vessels and Piping}, volume = {111-112}, pages = {187 - 201}, abstract = {The determination of the exact mechanical properties of material is essential for an optimal and safe design of linepipes. It is especially important for the prevention of over-engineering and the reliable assessment of complex accidental loading, such as extreme bending due to loss of buoyancy of support, or abrupt ground movement. Currently, the focus of research in offshore deepwater installations and linepipes is towards pre-cracked structures with high triaxiality stress states and complex loading histories. At the same time, low triaxiality stress states must be correctly studied in order to represent shear dominated failure in pipes. A comprehensive experimental and numerical program was undertaken to determine the mechanical properties of the traditional API X70 grade of steel. The material was characterized for anisotropic plasticity, fracture initiation and uncracked ductility for various states of stress. The same material was also used for pre-cracked fracture toughness assessment. The experimental program included flat and round specimens. The first type of tests on flat butterfly-shaped, central hole, notched and circular disk specimens; were selected to address the low stress triaxiality range. Tests on round notched bar specimens and SENT fracture mechanics tests extended the characterization and verification process to higher stress triaxiality values. This program covered a wide range of stress conditions and demonstrated their effect on the material resistance to crack extension. Each test conducted was numerically simulated using solid finite element models, matching the exact geometric and loading history features. The numerical simulation provided information on the local stress and strain fields around the location of the potential or existing cracks. Based on the above hybrid experimental/numerical technique tailored for pipe applications, the MMC fracture model was calibrated. The model relates the material ductility not only to stress triaxiality but also to the Lode parameter. The predictive capabilities of the MMC were then evaluated in the case of SENT testing, used extensively in the pipeline industry. It was shown that the present fracture model calibration can describe fracture behavior of SENT experiments.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The determination of the exact mechanical properties of material is essential for an optimal and safe design of linepipes. It is especially important for the prevention of over-engineering and the reliable assessment of complex accidental loading, such as extreme bending due to loss of buoyancy of support, or abrupt ground movement. Currently, the focus of research in offshore deepwater installations and linepipes is towards pre-cracked structures with high triaxiality stress states and complex loading histories. At the same time, low triaxiality stress states must be correctly studied in order to represent shear dominated failure in pipes. A comprehensive experimental and numerical program was undertaken to determine the mechanical properties of the traditional API X70 grade of steel. The material was characterized for anisotropic plasticity, fracture initiation and uncracked ductility for various states of stress. The same material was also used for pre-cracked fracture toughness assessment. The experimental program included flat and round specimens. The first type of tests on flat butterfly-shaped, central hole, notched and circular disk specimens; were selected to address the low stress triaxiality range. Tests on round notched bar specimens and SENT fracture mechanics tests extended the characterization and verification process to higher stress triaxiality values. This program covered a wide range of stress conditions and demonstrated their effect on the material resistance to crack extension. Each test conducted was numerically simulated using solid finite element models, matching the exact geometric and loading history features. The numerical simulation provided information on the local stress and strain fields around the location of the potential or existing cracks. Based on the above hybrid experimental/numerical technique tailored for pipe applications, the MMC fracture model was calibrated. The model relates the material ductility not only to stress triaxiality but also to the Lode parameter. The predictive capabilities of the MMC were then evaluated in the case of SENT testing, used extensively in the pipeline industry. It was shown that the present fracture model calibration can describe fracture behavior of SENT experiments. |
2012 |
Nonn, A.; Kalwa, C. Simulation of ductile crack propagation in high-strength pipeline steel using damage models Werkstoffsimulation Inproceedings 9th International Pipeline Conference 2012 (IPC 2012), Calgary, Canada, 2012. @inproceedings{Nonn2012, title = {Simulation of ductile crack propagation in high-strength pipeline steel using damage models}, author = {A. Nonn and C. Kalwa}, year = {2012}, date = {2012-09-24}, booktitle = {9th International Pipeline Conference 2012 (IPC 2012)}, address = {Calgary, Canada}, abstract = {The performance of engineering design of high-strength steel pipelines has revealed the necessity to revise current design procedures. Therefore, an improved and detailed comprehension of fracture mechanisms and development of failure prediction tools are required in order to derive new design criteria. In last decades the most successful failure prediction tools for steel structures subjected to various type of loading can be encountered in the field of damage mechanics. This paper aims to describe ductile fracture behavior of high-strength steel pipelines by applying three different damage models, Gurson-Tvergaard-Needelman (GTN), Fracture Locus Curve (FLC) and Cohesive Zone (CZ). These models are evaluated regarding their capability to estimate ductile crack propagation in laboratory specimens and linepipe components without adjusting the calibrated parameters. It can be shown that appropriate parameter sets can be identified to reproduce load-deformation and fracture resistance curves accurately. The strain rate effect on the fracture behavior is examined by dynamic tests on the BDWT specimens. Finally, the shortcomings of the applied models are pointed out with the reference to possible extensions and modifications.}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } The performance of engineering design of high-strength steel pipelines has revealed the necessity to revise current design procedures. Therefore, an improved and detailed comprehension of fracture mechanisms and development of failure prediction tools are required in order to derive new design criteria. In last decades the most successful failure prediction tools for steel structures subjected to various type of loading can be encountered in the field of damage mechanics. This paper aims to describe ductile fracture behavior of high-strength steel pipelines by applying three different damage models, Gurson-Tvergaard-Needelman (GTN), Fracture Locus Curve (FLC) and Cohesive Zone (CZ). These models are evaluated regarding their capability to estimate ductile crack propagation in laboratory specimens and linepipe components without adjusting the calibrated parameters. It can be shown that appropriate parameter sets can be identified to reproduce load-deformation and fracture resistance curves accurately. The strain rate effect on the fracture behavior is examined by dynamic tests on the BDWT specimens. Finally, the shortcomings of the applied models are pointed out with the reference to possible extensions and modifications. |
Schmid, V.; Jungbauer, B.; Romano, M.; Ehrlich, I.; Gebbeken, N. Diminution of mass of different types of fibre reinforcements due to thermal load. Leichtbau Inproceedings Mottok, J; Ziemann, O (Hrsg.): Applied Research Conference 2012 – ARC 2012, S. 231–235, Shaker-Verlag, 2012, ISBN: 978-3-8440-1093-0. @inproceedings{Schmid2012, title = {Diminution of mass of different types of fibre reinforcements due to thermal load. }, author = {V. Schmid and B. Jungbauer and M. Romano and I. Ehrlich and N. Gebbeken}, editor = {J. Mottok and O. Ziemann}, isbn = {978-3-8440-1093-0}, year = {2012}, date = {2012-06-25}, booktitle = {Applied Research Conference 2012 – ARC 2012}, pages = {231--235}, publisher = {Shaker-Verlag}, abstract = {The determination of the fibre volume content in fibre reinforced plastics is usually done by removing the matrix of a representative specimen after the material has been produced. For the removal of a polymeric matrix system two possibilities exist. The matrix can either be extracted chemically or thermally where the fibre reinforcement must not be affected. In the following the applicability of thermally removing the matrix for basalt fibre reinforced plastics is examined. Therefore the diminution of mass of different types of fibre reinforcements is experimentally investigated. The thermal removal of a polymeric matrix system is shown to be suitable for basalt fibre reinforced plastics as well as for glass fibre reinforced plastics.}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } The determination of the fibre volume content in fibre reinforced plastics is usually done by removing the matrix of a representative specimen after the material has been produced. For the removal of a polymeric matrix system two possibilities exist. The matrix can either be extracted chemically or thermally where the fibre reinforcement must not be affected. In the following the applicability of thermally removing the matrix for basalt fibre reinforced plastics is examined. Therefore the diminution of mass of different types of fibre reinforcements is experimentally investigated. The thermal removal of a polymeric matrix system is shown to be suitable for basalt fibre reinforced plastics as well as for glass fibre reinforced plastics. |
Schmid, V.; Jungbauer, B.; Romano, M.; Ehrlich, I.; Gebbeken, N. The influence of different types of fabrics on the fibre volume content and porosity in basalt fibre reinforced plastics. Leichtbau Inproceedings Mottok, J; Ziemann, O (Hrsg.): Applied Research Conference 2012 – ARC 2012, S. 162–165, Shaker-Verlag, 2012, ISBN: 978-3-8440-1093-0. @inproceedings{Schmid2012b, title = {The influence of different types of fabrics on the fibre volume content and porosity in basalt fibre reinforced plastics.}, author = {V. Schmid and B. Jungbauer and M. Romano and I. Ehrlich and N. Gebbeken}, editor = {J. Mottok and O. Ziemann}, isbn = {978-3-8440-1093-0}, year = {2012}, date = {2012-06-25}, booktitle = {Applied Research Conference 2012 – ARC 2012}, pages = {162--165}, publisher = {Shaker-Verlag}, abstract = {High quality semi-finished products with reproducible properties of basaltic fibres are hardly available on the market. In order to examine the properties of basalt fibre reinforced plastics high quality specimens are necessary. The fibre volume content and the porosity of the produced specimen are used as the typical criteria to evaluate the achieved quality of the produced material. The effect of the geometrical properties of the different semi-finished products on the fibre volume contents is relatively small whereas the porosity content is considerably affected.}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } High quality semi-finished products with reproducible properties of basaltic fibres are hardly available on the market. In order to examine the properties of basalt fibre reinforced plastics high quality specimens are necessary. The fibre volume content and the porosity of the produced specimen are used as the typical criteria to evaluate the achieved quality of the produced material. The effect of the geometrical properties of the different semi-finished products on the fibre volume contents is relatively small whereas the porosity content is considerably affected. |
Kofiani, K.; Nonn, A.; Wierzbicki, T.; Kalwa, C.; Walters, C. Experiments and fracture modeling of high-strength pipelines for high and low stress triaxiality Werkstoffsimulation Inproceedings The 22nd International Society of Offshore and Polar Engineering 2012 (ISOPE 2012), Rhodes, Greece, 2012. @inproceedings{Kofiani2012, title = {Experiments and fracture modeling of high-strength pipelines for high and low stress triaxiality}, author = {K. Kofiani and A. Nonn and T. Wierzbicki and C. Kalwa and C. Walters}, year = {2012}, date = {2012-06-17}, booktitle = {The 22nd International Society of Offshore and Polar Engineering 2012 (ISOPE 2012)}, address = {Rhodes, Greece}, abstract = {This paper provides results from a comprehensive study on mechanical characterization of high-strength pipeline steel, grade X100 using experimental and numerical methods. The material was characterized for anisotropic plasticity, fracture initiation for various states of stress, (pre-cracked) fracture toughness and uncracked ductility. The experimental program included tests on flat butterfly-shaped, central hole, notched and circular disk specimens for low stress triaxiality levels; as well as tests on round notched bar specimens and SENT fracture mechanics tests, for high values of stress triaxiality. This program covered a wide range of stress conditions and demonstrated its effect on the material resistance. Parallel to the experimental study, detailed numerical investigations were carried out to simulate all different experimental tests. Using an inverse method, a 3-parameter calibration was performed on the Modified Mohr-Coulomb (MMC) fracture model. Subsequently, the predictive capabilities of the MMC were evaluated by the comparison to the fracture toughness tests results, used extensively in the pipeline industry. The capabilities of the MIT fracture model have been demonstrated on an example of high strength offshore steel, X100. The outcome of this study was not only to provide, the overall characterization of the fracture behavior of this material as an example, but also to present the methodology on how to use the MMC model as a practical tool in pipeline design.}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } This paper provides results from a comprehensive study on mechanical characterization of high-strength pipeline steel, grade X100 using experimental and numerical methods. The material was characterized for anisotropic plasticity, fracture initiation for various states of stress, (pre-cracked) fracture toughness and uncracked ductility. The experimental program included tests on flat butterfly-shaped, central hole, notched and circular disk specimens for low stress triaxiality levels; as well as tests on round notched bar specimens and SENT fracture mechanics tests, for high values of stress triaxiality. This program covered a wide range of stress conditions and demonstrated its effect on the material resistance. Parallel to the experimental study, detailed numerical investigations were carried out to simulate all different experimental tests. Using an inverse method, a 3-parameter calibration was performed on the Modified Mohr-Coulomb (MMC) fracture model. Subsequently, the predictive capabilities of the MMC were evaluated by the comparison to the fracture toughness tests results, used extensively in the pipeline industry. The capabilities of the MIT fracture model have been demonstrated on an example of high strength offshore steel, X100. The outcome of this study was not only to provide, the overall characterization of the fracture behavior of this material as an example, but also to present the methodology on how to use the MMC model as a practical tool in pipeline design. |
Nonn, A.; Kalwa, C. Failure modeling of pipeline X100 Material in temperature transition region Werkstoffsimulation Inproceedings The 22nd International Society of Offshore and Polar Engineering 2012 (ISOPE 2012), Rhodes, Greece, 2012. @inproceedings{Nonn2012b, title = {Failure modeling of pipeline X100 Material in temperature transition region}, author = {A. Nonn and C. Kalwa}, year = {2012}, date = {2012-06-17}, booktitle = {The 22nd International Society of Offshore and Polar Engineering 2012 (ISOPE 2012)}, address = {Rhodes, Greece}, abstract = {This paper focuses on the characterization of the fracture performance of X100 material in transition temperature region using both experimental and numerical methods. The ductile fracture has been analyzed using tests on round notched bar specimens and standard fracture mechanics tests performed at room temperature. In previous publications the damage model Gurson-Tvergaard-Needleman (GTN) has been applied and verified by existing experimental data to describe ductile fracture behavior. The brittle fracture and the fracture in temperature transition region have been studied by means of deep and shallow notched SENB specimens at two different temperatures T=-80°C and -40°C. Besides elastic-plastic analyses to quantify constraint levels for different initial crack configurations at the onset of cleavage fracture, the brittle failure has been described using modified Beremin model. The influence of the stable crack growth on the cleavage failure probability in temperature transition region has been captured by coupling the ductile fracture model (GTN) with the modified Beremin model. Finally, examples have been presented for the practical application of the numerical results on the fracture assessment of the flawed high-strength pipelines.}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } This paper focuses on the characterization of the fracture performance of X100 material in transition temperature region using both experimental and numerical methods. The ductile fracture has been analyzed using tests on round notched bar specimens and standard fracture mechanics tests performed at room temperature. In previous publications the damage model Gurson-Tvergaard-Needleman (GTN) has been applied and verified by existing experimental data to describe ductile fracture behavior. The brittle fracture and the fracture in temperature transition region have been studied by means of deep and shallow notched SENB specimens at two different temperatures T=-80°C and -40°C. Besides elastic-plastic analyses to quantify constraint levels for different initial crack configurations at the onset of cleavage fracture, the brittle failure has been described using modified Beremin model. The influence of the stable crack growth on the cleavage failure probability in temperature transition region has been captured by coupling the ductile fracture model (GTN) with the modified Beremin model. Finally, examples have been presented for the practical application of the numerical results on the fracture assessment of the flawed high-strength pipelines. |
Ottawa, P.; Romano, M.; Ehrlich, I.; Wagner, M.; Gebbeken, N. The influence of ondulation in fabric reinforced composites on dynamic properties in a mesoscopic scale. Leichtbau Inproceedings 11. LS-DYNA Forum, Ulm, 2012. @inproceedings{Ottawa2012, title = {The influence of ondulation in fabric reinforced composites on dynamic properties in a mesoscopic scale.}, author = {P. Ottawa and M. Romano and I. Ehrlich and M. Wagner and N. Gebbeken}, year = {2012}, date = {2012-01-01}, booktitle = {11. LS-DYNA Forum}, address = {Ulm}, abstract = {Structural mechanic properties of fiber reinforced plastics depend on the single components’ properties, namely matrix and fiber [5]. Simple micromechanic homogenization theories reach a limit when a laminate consists of fabric reinforced layers instead of unidirectional layers. The ondulations of warp and fill yarn caused by the textile semi-finished product are the reason why the mesoscopic scale, which is in between the microscopic and the macroscopic scale, has to be taken into account when mechanically characterizing fabric reinforced composites [3]. In this scale a mesomechanic kinematic can be derived analytically. Especially, when considering free damped vibrations of structures the repeated acting of the kinematic correlation significantly affects the damping behaviour to higher values compared to theoretically predicted damping ratios. The model is investigated using Finite-Element-Analyses and basically validated experimentally. }, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } Structural mechanic properties of fiber reinforced plastics depend on the single components’ properties, namely matrix and fiber [5]. Simple micromechanic homogenization theories reach a limit when a laminate consists of fabric reinforced layers instead of unidirectional layers. The ondulations of warp and fill yarn caused by the textile semi-finished product are the reason why the mesoscopic scale, which is in between the microscopic and the macroscopic scale, has to be taken into account when mechanically characterizing fabric reinforced composites [3]. In this scale a mesomechanic kinematic can be derived analytically. Especially, when considering free damped vibrations of structures the repeated acting of the kinematic correlation significantly affects the damping behaviour to higher values compared to theoretically predicted damping ratios. The model is investigated using Finite-Element-Analyses and basically validated experimentally. |
2011 |
Nonn, A.; Kalwa, C. The effect of microstructure, strain hardening and strain rate on the fracture behavior of high strength pipeline steels Werkstoffsimulation Inproceedings 2nd International Conference on Material Modelling (ICMM2), Paris, France, 2011. @inproceedings{, title = {The effect of microstructure, strain hardening and strain rate on the fracture behavior of high strength pipeline steels}, author = {A. Nonn and C. Kalwa}, year = {2011}, date = {2011-08-31}, booktitle = {2nd International Conference on Material Modelling (ICMM2)}, address = {Paris, France}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
2010 |
Nonn, A.; Erdelen-Peppler, M.; Kalwa, C. Numerical and experimental investigation of the influence of HAZ on the fracture behavior of longitudinal welded linepipes Werkstoffsimulation Inproceedings Fracture of Materials and Structures from Micro to Macro Scale, 18th European Conference on Fracture, Dresden, Germany, 2010. @inproceedings{, title = {Numerical and experimental investigation of the influence of HAZ on the fracture behavior of longitudinal welded linepipes}, author = {A. Nonn and M. Erdelen-Peppler and C. Kalwa}, year = {2010}, date = {2010-08-30}, booktitle = {Fracture of Materials and Structures from Micro to Macro Scale, 18th European Conference on Fracture}, address = {Dresden, Germany}, abstract = {The present paper deals with the influence of heat affected zone (henceforth HAZon the fracture performance of longitudinal welded linepipes in dependence on constraint level. It has been shown that toughness values of HAZ obtained from standard fracture mechanics tests lead to uneconomic linepipe design for two reasons. The first reason is that laboratory specimens with higher constraint level generally exhibit lower fracture resistance compared to flawed linepipes. The second one has to do with a higher probability of cleavage failure occurrence in the laboratory specimen than in the linepipes due to larger areas of lower toughness (so called local brittle zones (LBZintersected by crack front. In recent years numerous studies have been initiated with the objective to quantify the constraint level and thus to allow for less conservative linepipe safety assessment by applying constraint corrected toughness values. However, the main focus of these studies has hitherto been on the homogeneous materials, failing to account for the possible effects of different microstructures within the heterogeneous HAZ. This paper seeks to close this gap by reporting on results from tests on fracture mechanics specimens of a high strength X80 steel, i.e. SENB and SENT specimens as well as results from ring expansion tests. Both, deep and shallow cracks are inserted in the fracture mechanics specimens and rings targeting the fusion line (FL. By varying the initial crack size and sample type, different constraint levels are achieved and subsequently quantified using numerical methods. Besides constraint observations, post metallographic analyses are performed to identify exact HAZ microstructure involved at the crack tip. Finally, the influence of HAZ properties, flaw size and geometry on the failure behaviour of the linepipes has been demonstrated and assessed. Based on the combination of the results from constraint studies and the post metallographic analyses, the methodology is proposed which enables simple quantitative prediction of toughness values for safe and economic design of linepipes with flaws located in HAZ.}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } The present paper deals with the influence of heat affected zone (henceforth HAZon the fracture performance of longitudinal welded linepipes in dependence on constraint level. It has been shown that toughness values of HAZ obtained from standard fracture mechanics tests lead to uneconomic linepipe design for two reasons. The first reason is that laboratory specimens with higher constraint level generally exhibit lower fracture resistance compared to flawed linepipes. The second one has to do with a higher probability of cleavage failure occurrence in the laboratory specimen than in the linepipes due to larger areas of lower toughness (so called local brittle zones (LBZintersected by crack front. In recent years numerous studies have been initiated with the objective to quantify the constraint level and thus to allow for less conservative linepipe safety assessment by applying constraint corrected toughness values. However, the main focus of these studies has hitherto been on the homogeneous materials, failing to account for the possible effects of different microstructures within the heterogeneous HAZ. This paper seeks to close this gap by reporting on results from tests on fracture mechanics specimens of a high strength X80 steel, i.e. SENB and SENT specimens as well as results from ring expansion tests. Both, deep and shallow cracks are inserted in the fracture mechanics specimens and rings targeting the fusion line (FL. By varying the initial crack size and sample type, different constraint levels are achieved and subsequently quantified using numerical methods. Besides constraint observations, post metallographic analyses are performed to identify exact HAZ microstructure involved at the crack tip. Finally, the influence of HAZ properties, flaw size and geometry on the failure behaviour of the linepipes has been demonstrated and assessed. Based on the combination of the results from constraint studies and the post metallographic analyses, the methodology is proposed which enables simple quantitative prediction of toughness values for safe and economic design of linepipes with flaws located in HAZ. |
Nonn, A.; Kalwa, C. Modeling of damage behavior of high strength pipeline steel Werkstoffsimulation Inproceedings Fracture of Materials and Structures from Micro to Macro Scale, 18th European Conference on Fracture, Dresden, Germany, 2010. @inproceedings{, title = {Modeling of damage behavior of high strength pipeline steel}, author = {A. Nonn and C. Kalwa}, year = {2010}, date = {2010-08-30}, booktitle = {Fracture of Materials and Structures from Micro to Macro Scale, 18th European Conference on Fracture}, address = {Dresden, Germany}, abstract = {The worldwide growing importance of oil and gas transport has led to increasing application of high strength steels, e.g. X100, for pipelines. Although the development of the new high-strength steel grades has been recently intensified, detailed comprehension of fracture performance of high strength linepipe is still missing. Hence, outdated methods are used for the design against fracture resulting in insufficient utilization of material reserves. This paper aims to provide overall characterization of mechanical properties of X100 pipeline steel and to allow for more precise estimation of failure process by taking the microstructure into account. By conducting metallographic analyses, the microstructure of X100 has been characterized with objective to identify variables, e.g. size and distribution of voids, inclusions and precipitations relevant for damage process. Subsequently, these variables have been linked to damage parameters of the micromechanics-based Gurson-Tvergaard-Needleman (henceforth GTN) model. This model adequately describes ductile failure for arbitrary crack and component geometry by incorporating the influence of local damage on the yielding behavior. However, it requires besides microstructural variables a quantification of additional parameters by performing tests on the round bar specimens with different notch geometry. The results from fracture mechanics tests on deep-notched SENB and SENT specimens serve the validation of GTN model with respect to accurate prediction of global load-deformation and crack resistance behavior. The transferability of the model parameters was demonstrated by means of results from tests on the shallow-notched specimens and ring expansion tests. Additionally, the effect of microstructure modification on fracture behavior of flawed linepipes was studied and evaluated by varying microstructure-related parameters, e.g. initial porosity f 0 and volume fraction of newly-nucleating voids f N . Based on the results obtained from damage modeling and parameter studies, recommendations have been derived for the modifications of X100 microstructure for purposes to improve toughness properties.}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } The worldwide growing importance of oil and gas transport has led to increasing application of high strength steels, e.g. X100, for pipelines. Although the development of the new high-strength steel grades has been recently intensified, detailed comprehension of fracture performance of high strength linepipe is still missing. Hence, outdated methods are used for the design against fracture resulting in insufficient utilization of material reserves. This paper aims to provide overall characterization of mechanical properties of X100 pipeline steel and to allow for more precise estimation of failure process by taking the microstructure into account. By conducting metallographic analyses, the microstructure of X100 has been characterized with objective to identify variables, e.g. size and distribution of voids, inclusions and precipitations relevant for damage process. Subsequently, these variables have been linked to damage parameters of the micromechanics-based Gurson-Tvergaard-Needleman (henceforth GTN) model. This model adequately describes ductile failure for arbitrary crack and component geometry by incorporating the influence of local damage on the yielding behavior. However, it requires besides microstructural variables a quantification of additional parameters by performing tests on the round bar specimens with different notch geometry. The results from fracture mechanics tests on deep-notched SENB and SENT specimens serve the validation of GTN model with respect to accurate prediction of global load-deformation and crack resistance behavior. The transferability of the model parameters was demonstrated by means of results from tests on the shallow-notched specimens and ring expansion tests. Additionally, the effect of microstructure modification on fracture behavior of flawed linepipes was studied and evaluated by varying microstructure-related parameters, e.g. initial porosity f 0 and volume fraction of newly-nucleating voids f N . Based on the results obtained from damage modeling and parameter studies, recommendations have been derived for the modifications of X100 microstructure for purposes to improve toughness properties. |
Nonn, A. Failure modeling of hybrid-laser welds in transition temperature region Werkstoffsimulation Inproceedings Fracture of Materials and Structures from Micro to Macro Scale, 18th European Conference on Fracture, Dresden, Germany, 2010. @inproceedings{, title = {Failure modeling of hybrid-laser welds in transition temperature region}, author = {A. Nonn}, year = {2010}, date = {2010-08-30}, booktitle = {Fracture of Materials and Structures from Micro to Macro Scale, 18th European Conference on Fracture}, address = {Dresden, Germany}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
2009 |
Bleck, W.; Dahl, W.; Nonn, A.; Amlung, L.; Feldmann, M.; Schäfer, D.; Eichler, B. Numerical and experimental analyses of damage behaviour of steel moment connection Werkstoffsimulation Artikel Engineering Fracture Mechanics, 76 (10), S. 1531 - 1547, 2009, ISSN: 0013-7944, (MatModels 2007). @article{BLECK20091531, title = {Numerical and experimental analyses of damage behaviour of steel moment connection}, author = {W. Bleck and W. Dahl and A. Nonn and L. Amlung and M. Feldmann and D. Schäfer and B. Eichler}, url = {http://www.sciencedirect.com/science/article/pii/S001379440900085X}, doi = {https://doi.org/10.1016/j.engfracmech.2009.03.004}, issn = {0013-7944}, year = {2009}, date = {2009-01-01}, journal = {Engineering Fracture Mechanics}, volume = {76}, number = {10}, pages = {1531 - 1547}, abstract = {Plastic design allows the exploitation of the full resistance of steel structures by taking advantage of stress–redistributions due to plastic strains exceeding the yield strain. Especially in seismic design the utilization of material reserves and the formation of plastic hinges play an important role. In devastating earthquakes in Northridge (USA) and Kobe (Japan) brittle fracture of welded connections in steel moment frames occurred prior to formation of plastic hinges and utilization of plastic material reserves. The subsequent research works resulted in improved design rules and recommendations for these kinds of failure. But to guarantee sufficient ductile performance of these connections also in the upper shelf region, plastic and earthquake resistant design rules should take into account degradation of strain capacity and toughness properties due to quasi static and especially seismic loading. In the scope of the current European project “Plastotough”, the main objective is to derive quantified toughness design rules in the upper shelf based on the strain requirements opposed to strain capacities. This paper gives an overview over the research work in performance and shows recent results from experimental and numerical analyses performed within this project for monotonic and cyclic loading.}, note = {MatModels 2007}, keywords = {}, pubstate = {published}, tppubtype = {article} } Plastic design allows the exploitation of the full resistance of steel structures by taking advantage of stress–redistributions due to plastic strains exceeding the yield strain. Especially in seismic design the utilization of material reserves and the formation of plastic hinges play an important role. In devastating earthquakes in Northridge (USA) and Kobe (Japan) brittle fracture of welded connections in steel moment frames occurred prior to formation of plastic hinges and utilization of plastic material reserves. The subsequent research works resulted in improved design rules and recommendations for these kinds of failure. But to guarantee sufficient ductile performance of these connections also in the upper shelf region, plastic and earthquake resistant design rules should take into account degradation of strain capacity and toughness properties due to quasi static and especially seismic loading. In the scope of the current European project “Plastotough”, the main objective is to derive quantified toughness design rules in the upper shelf based on the strain requirements opposed to strain capacities. This paper gives an overview over the research work in performance and shows recent results from experimental and numerical analyses performed within this project for monotonic and cyclic loading. |
2008 |
Nonn, A.; Dahl, W.; Bleck, W. Numerical modelling of damage behaviour of laser-hybrid welds Werkstoffsimulation Artikel Engineering Fracture Mechanics, 75 (11), S. 3251 - 3263, 2008, ISSN: 0013-7944, (Local Approach to Fracture (1986–2006): Selected papers from the 9th European Mechanics of Materials Conference). @article{NONN20083251, title = {Numerical modelling of damage behaviour of laser-hybrid welds}, author = {A. Nonn and W. Dahl and W. Bleck}, url = {http://www.sciencedirect.com/science/article/pii/S0013794407003943}, doi = {https://doi.org/10.1016/j.engfracmech.2007.10.015}, issn = {0013-7944}, year = {2008}, date = {2008-01-01}, journal = {Engineering Fracture Mechanics}, volume = {75}, number = {11}, pages = {3251 - 3263}, abstract = {The effect of laser-hybrid welds on deformation and failure behaviour of fracture mechanics specimens is investigated in order to provide quantitative prediction of damage tolerance and residual strength. The simulation of crack initiation and crack extension in hybrid welds is performed by applying GTN damage model. The identification of damage parameters requires combined numerical and experimental analyses. The tendency to crack path deviation during crack growth depends strongly on the constraint development at the interface between base and weld metal. In order to quantify the influence of local stress state on the crack path deviation, the initial crack location is varied. Finally, the results from fracture mechanics tests are compared to real component, beam-column-connection, with respect to fracture resistance.}, note = {Local Approach to Fracture (1986–2006): Selected papers from the 9th European Mechanics of Materials Conference}, keywords = {}, pubstate = {published}, tppubtype = {article} } The effect of laser-hybrid welds on deformation and failure behaviour of fracture mechanics specimens is investigated in order to provide quantitative prediction of damage tolerance and residual strength. The simulation of crack initiation and crack extension in hybrid welds is performed by applying GTN damage model. The identification of damage parameters requires combined numerical and experimental analyses. The tendency to crack path deviation during crack growth depends strongly on the constraint development at the interface between base and weld metal. In order to quantify the influence of local stress state on the crack path deviation, the initial crack location is varied. Finally, the results from fracture mechanics tests are compared to real component, beam-column-connection, with respect to fracture resistance. |
2007 |
Nonn, A.; Dahl, W.; Bleck, W. Damage Modelling and Safety Assessment of the Hybrid Welded Structures Werkstoffsimulation Inproceedings 5th German-Japanese Seminar “Materials, Processes and Components”, Fraunhofer Institute for Mechanics of Materials, Freiburg, Germany, 2007. @inproceedings{, title = {Damage Modelling and Safety Assessment of the Hybrid Welded Structures}, author = {A. Nonn and W. Dahl and W. Bleck}, year = {2007}, date = {2007-06-27}, booktitle = {5th German-Japanese Seminar “Materials, Processes and Components”}, address = {Fraunhofer Institute for Mechanics of Materials, Freiburg, Germany}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
Nonn, A.; Dahl, W.; Bleck, W. Numerical and experimental analyses of damage behaviour of steel moment connections Werkstoffsimulation Inproceedings MatMod2007, Material Models – from Nano to Macro, International Workshop, Hamburg, Germany, 2007. @inproceedings{, title = {Numerical and experimental analyses of damage behaviour of steel moment connections}, author = {A. Nonn and W. Dahl and W. Bleck}, year = {2007}, date = {2007-06-11}, booktitle = {MatMod2007, Material Models – from Nano to Macro, International Workshop}, address = {Hamburg, Germany}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |