2018
|
Nonn, A.; Paredes, M.; Keim, V.; Wierzbicki, T. Comparison of Fracture Models to Quantify the Effects of Material Plasticity on the Ductile Fracture Propagation in Pipelines Werkstoffsimulation Inproceedings Proceedings of the 2018 12th International Pipeline Conference, Volume 3: Operations, Monitoring, and Maintenance, Materials and Joining, Calgary, Alberta, Canada, 2018, ISBN: 978-0-7918-5188-3. Abstract | Links | BibTeX @inproceedings{Nonn2018,
title = {Comparison of Fracture Models to Quantify the Effects of Material Plasticity on the Ductile Fracture Propagation in Pipelines},
author = {A. Nonn and M. Paredes and V. Keim and T. Wierzbicki},
doi = {10.1115/IPC2018-78366},
isbn = {978-0-7918-5188-3},
year = {2018},
date = {2018-09-24},
booktitle = {Proceedings of the 2018 12th International Pipeline Conference, Volume 3: Operations, Monitoring, and Maintenance, Materials and Joining},
address = {Calgary, Alberta, Canada},
series = {International Pipeline Conference},
abstract = {Various numerical approaches have been developed in the last years aimed to simulate the ductile fracture propagation in pipelines transporting CO2 or natural gas. However, a reliable quantification of the influence of material plasticity on the fracture resistance is still missing. Therefore, more accurate description of the material plasticity on the ductile fracture propagation is required based on a suitable numerical methodology.In this study, different plasticity and fracture models are compared regarding the ductile fracture propagation in X100 pipeline steel with the objective to quantify the influence of plasticity parameters on the fracture resistance. The plastic behavior of the investigated material is considered by the quadratic yield surface in conjunction with a non-associated quadratic plastic flow potential. The strain hardening can be appropriately described by the mixed Swift-Voce law. The simulations of ductile fracture are conducted by an uncoupled, modified Mohr-Coulomb (MMC) and the micromechanically based Gurson-Tvergaard-Needleman (GTN) models. In contract to the original GTN model, the MMC model is capable of describing ductile failure over wide range of stress states. Thus, ductile fracture resistance can be estimated for various load and fracture scenarios. Both models are used for the simulation of fracture propagation in DWTT and 3D pressurized pipe sections. The results from the present work can serve as a basis for establishing the correlation between plasticity parameters and ductile fracture propagation.},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
Various numerical approaches have been developed in the last years aimed to simulate the ductile fracture propagation in pipelines transporting CO2 or natural gas. However, a reliable quantification of the influence of material plasticity on the fracture resistance is still missing. Therefore, more accurate description of the material plasticity on the ductile fracture propagation is required based on a suitable numerical methodology.In this study, different plasticity and fracture models are compared regarding the ductile fracture propagation in X100 pipeline steel with the objective to quantify the influence of plasticity parameters on the fracture resistance. The plastic behavior of the investigated material is considered by the quadratic yield surface in conjunction with a non-associated quadratic plastic flow potential. The strain hardening can be appropriately described by the mixed Swift-Voce law. The simulations of ductile fracture are conducted by an uncoupled, modified Mohr-Coulomb (MMC) and the micromechanically based Gurson-Tvergaard-Needleman (GTN) models. In contract to the original GTN model, the MMC model is capable of describing ductile failure over wide range of stress states. Thus, ductile fracture resistance can be estimated for various load and fracture scenarios. Both models are used for the simulation of fracture propagation in DWTT and 3D pressurized pipe sections. The results from the present work can serve as a basis for establishing the correlation between plasticity parameters and ductile fracture propagation. |
Paredes, M.; Keim, V.; Nonn, A.; Wierzbicki, T. Effect of plasticity parameter on the crack propagation in steel pipelines Werkstoffsimulation Inproceedings Proceedings of the conference on Technology for future and ageing piplines, Ghent, Belgium, 2018. Abstract | BibTeX @inproceedings{Paredes2018,
title = {Effect of plasticity parameter on the crack propagation in steel pipelines},
author = {M. Paredes and V. Keim and A. Nonn and T. Wierzbicki},
year = {2018},
date = {2018-04-01},
booktitle = {Proceedings of the conference on Technology for future and ageing piplines},
address = {Ghent, Belgium},
abstract = {A reliable characterization of material fracture resistance and derivation of ductile-fracture-arrest criteria for modern linepipe steels belong to major challenges within the current pipeline research. Although many efforts have been undertaken to meet these challenges, there are still open issues related to the understanding and quantification of the material properties on unstable ductile fracture propagation. There is a general consensus that the fracture velocity is controlled by the speed of travelling plastic hinge (propagating neck or plastic instability/collapse) due to axial through-wall thinning in front of the fracture. To account for the effect of material ductility on fracture propagation resistance, a plasticity parameter, the yield-to-tensile ratio, has been recently implemented in the Battelle fracture velocity model. The improved results from this modification indicate that an accurate prediction of crack propagation and arrest require a comprehensive characterization and consideration of material plasticity and fracture.
Therefore, this paper aims to study and quantify the influence of plasticity (characteristic stress/strain values, strain hardening, plastic anisotropy) parameters on dynamic crack propagation in the X100 steel pipelines. Plastic anisotropy is described by Hill’48 quadratic yield function along with a non-associated flow rule which allows to incorporate the effect of a different directionality of the r-values from the yield stress ratios without losing advantages of quadratic functions. The strain hardening is captured by a linear combination of Swift power law and Voce exponential law. The ductile fracture propagation is simulated by Modified-Mohr-Coulomb (MMC) fracture model which includes a joint effect of stress triaxiality, Lode angle and is applicable to problems with changing loading history. The model parameters are verified based on results from single-edge-notched (SENT) and drop-weight-tear-test (DWTT) tests. The influence of plasticity parameters on the fracture propagation is examined and quantified using 3D pressurized pipe models. The results will provide valuable insights on key plasticity parameters affecting fracture resistance and thus serve as a basis for more accurate assessment of deformation/fracture process of the modern pipeline steels.},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
A reliable characterization of material fracture resistance and derivation of ductile-fracture-arrest criteria for modern linepipe steels belong to major challenges within the current pipeline research. Although many efforts have been undertaken to meet these challenges, there are still open issues related to the understanding and quantification of the material properties on unstable ductile fracture propagation. There is a general consensus that the fracture velocity is controlled by the speed of travelling plastic hinge (propagating neck or plastic instability/collapse) due to axial through-wall thinning in front of the fracture. To account for the effect of material ductility on fracture propagation resistance, a plasticity parameter, the yield-to-tensile ratio, has been recently implemented in the Battelle fracture velocity model. The improved results from this modification indicate that an accurate prediction of crack propagation and arrest require a comprehensive characterization and consideration of material plasticity and fracture.
Therefore, this paper aims to study and quantify the influence of plasticity (characteristic stress/strain values, strain hardening, plastic anisotropy) parameters on dynamic crack propagation in the X100 steel pipelines. Plastic anisotropy is described by Hill’48 quadratic yield function along with a non-associated flow rule which allows to incorporate the effect of a different directionality of the r-values from the yield stress ratios without losing advantages of quadratic functions. The strain hardening is captured by a linear combination of Swift power law and Voce exponential law. The ductile fracture propagation is simulated by Modified-Mohr-Coulomb (MMC) fracture model which includes a joint effect of stress triaxiality, Lode angle and is applicable to problems with changing loading history. The model parameters are verified based on results from single-edge-notched (SENT) and drop-weight-tear-test (DWTT) tests. The influence of plasticity parameters on the fracture propagation is examined and quantified using 3D pressurized pipe models. The results will provide valuable insights on key plasticity parameters affecting fracture resistance and thus serve as a basis for more accurate assessment of deformation/fracture process of the modern pipeline steels. |
Keim, V.; Nonn, A.; Lenz, D.; Brinnel, V.; Münstermann, S. Simulation of the ductile fracture behaviour of high toughness pipeline steels using combined damage models Werkstoffsimulation Inproceedings Proceedings of the conference on Technology for future and ageing piplines, Ghent, Belgium, 2018. Abstract | BibTeX @inproceedings{Keim2018,
title = {Simulation of the ductile fracture behaviour of high toughness pipeline steels using combined damage models},
author = {V. Keim and A. Nonn and D. Lenz and V. Brinnel and S. Münstermann},
year = {2018},
date = {2018-01-01},
booktitle = {Proceedings of the conference on Technology for future and ageing piplines},
address = {Ghent, Belgium},
abstract = {The complex mechanical and corrosive loads of modern pipeline systems transporting oil, natural gas and CO2 impose steadily increasing requirements on material properties. The majority of current design standards still limit the application of modern high toughness linepipe steels due to the specification of material requirements in terms of energy levels from Charpy impact or Drop-Weight-Tear tests (DWTT). Furthermore, abnormal fracture appearance (AFA), abnormal fracture behavior (AFB) and separations question the correlation between laboratory tests and components’ fracture behavior. In consequence, research activities have been conducted recently aiming at developing modified or novel experimental methods for the characterization of ductile-to-brittle fracture behavior. To quantify the effects of various parameters on fracture behavior and derive suitable correlations, it is necessary to accompany these activities by numerical simulations with appropriate damage models for ductile and cleavage fracture. In this paper, a coupled, phenomenological damage model for ductile fracture is applied to study the structural behavior of pipelines due to its pronounced computational efficiency, which is combined with a cleavage fracture model in later phases of the project. The parameters for the model are determined by small scale tests with various multi-axial loading conditions. The validated damage model was successfully used to simulate the fracture behavior DWTT specimens. Finally, these models allow for the investigation of material, geometry and loading effects on fracture and crack arrest behavior of pipes in transition region.},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
The complex mechanical and corrosive loads of modern pipeline systems transporting oil, natural gas and CO2 impose steadily increasing requirements on material properties. The majority of current design standards still limit the application of modern high toughness linepipe steels due to the specification of material requirements in terms of energy levels from Charpy impact or Drop-Weight-Tear tests (DWTT). Furthermore, abnormal fracture appearance (AFA), abnormal fracture behavior (AFB) and separations question the correlation between laboratory tests and components’ fracture behavior. In consequence, research activities have been conducted recently aiming at developing modified or novel experimental methods for the characterization of ductile-to-brittle fracture behavior. To quantify the effects of various parameters on fracture behavior and derive suitable correlations, it is necessary to accompany these activities by numerical simulations with appropriate damage models for ductile and cleavage fracture. In this paper, a coupled, phenomenological damage model for ductile fracture is applied to study the structural behavior of pipelines due to its pronounced computational efficiency, which is combined with a cleavage fracture model in later phases of the project. The parameters for the model are determined by small scale tests with various multi-axial loading conditions. The validated damage model was successfully used to simulate the fracture behavior DWTT specimens. Finally, these models allow for the investigation of material, geometry and loading effects on fracture and crack arrest behavior of pipes in transition region. |
2017
|
Nonn, A.; Paredes, M.; Nordhagen, H. O.; Munkejord, S. T.; Wierzbicki, T. Challenges in fluid-structure modeling of crack propagation and arrest in modern steel pipelines Werkstoffsimulation Inproceedings 14th International Congress on Fracture (ICF14), Rhodes, Greece, 2017. BibTeX @inproceedings{Nonn2017,
title = {Challenges in fluid-structure modeling of crack propagation and arrest in modern steel pipelines},
author = {A. Nonn and M. Paredes and H. O. Nordhagen and S. T. Munkejord and T. Wierzbicki},
year = {2017},
date = {2017-06-18},
booktitle = {14th International Congress on Fracture (ICF14)},
address = {Rhodes, Greece},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
|
2016
|
Cerrone, A. R.; Nonn, A.; Hochhalter, J. D.; Bomarito, G. F.; Warner, J. E.; Carter, B. J.; Warner, D. H.; Ingraffea, A. R. Predicting failure of the Second Sandia Fracture Challenge geometry with a real-world, time constrained, over-the-counter methodology Werkstoffsimulation Artikel International Journal of Fracture, 198 (1), S. 117-126, 2016, ISSN: 1573-2673. Abstract | Links | BibTeX @article{Cerrone2016,
title = {Predicting failure of the Second Sandia Fracture Challenge geometry with a real-world, time constrained, over-the-counter methodology},
author = {A. R. Cerrone and A. Nonn and J. D. Hochhalter and G. F. Bomarito and J. E. Warner and B. J. Carter and D. H. Warner and A. R. Ingraffea},
url = {https://doi.org/10.1007/s10704-016-0086-x},
doi = {10.1007/s10704-016-0086-x},
issn = {1573-2673},
year = {2016},
date = {2016-03-01},
journal = {International Journal of Fracture},
volume = {198},
number = {1},
pages = {117-126},
abstract = {An over-the-counter methodology to predict fracture initiation and propagation in the challenge specimen of the Second Sandia Fracture Challenge is detailed herein. This pragmatic approach mimics that of an engineer subjected to real-world time constraints and unquantified uncertainty. First, during the blind prediction phase of the challenge, flow and failure locus curves were calibrated for Ti--6Al--4V with provided tensile and shear test data for slow (0.0254 mm/s) and fast (25.4 mm/s) loading rates. Thereafter, these models were applied to a 3D finite-element mesh of the non-standardized challenge geometry with nominal dimensions to predict, among other items, crack path and specimen response. After the blind predictions were submitted to Sandia National Labs, they were improved upon by addressing anisotropic yielding, damage initiation under shear dominance, and boundary condition selection.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
An over-the-counter methodology to predict fracture initiation and propagation in the challenge specimen of the Second Sandia Fracture Challenge is detailed herein. This pragmatic approach mimics that of an engineer subjected to real-world time constraints and unquantified uncertainty. First, during the blind prediction phase of the challenge, flow and failure locus curves were calibrated for Ti--6Al--4V with provided tensile and shear test data for slow (0.0254 mm/s) and fast (25.4 mm/s) loading rates. Thereafter, these models were applied to a 3D finite-element mesh of the non-standardized challenge geometry with nominal dimensions to predict, among other items, crack path and specimen response. After the blind predictions were submitted to Sandia National Labs, they were improved upon by addressing anisotropic yielding, damage initiation under shear dominance, and boundary condition selection. |
