Leichtbau

@article{Siegl2024,

title = {Winding process of fibre-reinforced thermoplastic tubes with integrated tape production through in-situ roving impregnation and infrared consolidation},

author = {M. Siegl and B. Jungbauer and J. Gebhardt and A. Judenmann and I. Ehrlich},

doi = {10.1007/s00170-024-14628-y},

issn = {1433-3015},

year  = {2024},

date = {2024-10-24},

urldate = {2024-10-24},

journal = {Int J Adv Manuf Technol},

volume = {135},

issue = {5-6},

pages = {2847 – 2870 },

publisher = {Springer Science and Business Media LLC},

abstract = {This paper introduces a novel method for producing fibre-reinforced thermoplastic tubes by integrating tape production and consolidation into a single operation. This innovation diverges from conventional methods by combining processes to reduce costs by using raw materials instead of organotapes, allowing customised material combinations and utilising residual heat from tape production. The new process uses carbon roving and molten low-viscosity PA6 granulates, processed through a new direct impregnation setup in siphon design. Key advancements include a high-speed impregnation module capable of up to 1 m/s with high-performance extruders, cost-effective infrared emitters for winding, and a powered consolidation unit with adjustable winding angles between ± 65° and ± 90°. Experiments demonstrate operational speeds of approximately 471 mm/min, with an optimal cross-winding speed of 354 mm/min due to the technical limitations of the laboratory extruder and IR emitter used. Based on the technical limitations of the current system, future improvements and methodological changes will be discussed.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{doi:10.1177/20414196241284297,

title = {Shock-tube tests on conventional windows: Exploring retrofit concepts for enhanced blast protection},

author = {M. Andrae and A. Kastenmeier and J. Gebhardt and I. Ehrlich and N. Gebbeken},

url = {https://doi.org/10.1177/20414196241284297},

doi = {10.1177/20414196241284297},

year  = {2024},

date = {2024-09-16},

journal = {International Journal of Protective Structures},

volume = {0},

number = {0},

pages = {20414196241284297},

abstract = {Ensuring blast protection for existing buildings, especially addressing the vulnerability of conventional windows, is a significant challenge. Such unprotected windows can shatter even with moderate blast loads, posing a substantial risk of injury to occupants. This article discusses experimental research on enhancing the blast protection of single casement windows with insulating glass units and frames made of unplasticized polyvinyl chloride (uPVC). A retrofit concept using anti-shatter films, metallic sash reinforcements, adhesive bonding of the glazing to the sash frame, and a burglary resistance fitting-system was developed and tested in an explosion-driven shock-tube. Moreover, novel patches made of glass fiber-reinforced polymer applied to the corners of the window frames have been tested and proven effective in providing additional strength to the window. The study concludes that the tested combination of retrofit measures can significantly reduce hazards from window fragments without compromising functionality or aesthetics.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Romano2024,

title = {Classification of damping properties of fabric-reinforced flat beam-like specimens by a degree of ondulation implying a mesomechanic kinematic},

author = {M. Romano and I. Ehrlich},

doi = {10.1515/secm-2024-0019},

issn = {2191-0359},

year  = {2024},

date = {2024-08-22},

urldate = {2024-08-22},

journal = {Science and Engineering of Composite Materials},

volume = {31},

number = {1},

publisher = {Walter de Gruyter GmbH},

abstract = {In order to determine the influence of the ondulations in fabrics on the damping properties of fiber-reinforced plastics, the structural dynamic properties of fabric- and unidirectionally reinforced plastics are investigated. The free decay behavior of flat beam-like specimens is investigated under fixed-free boundary conditions. As the material damping is consistently higher in fabric-reinforced specimens compared to unidirectionally reinforced ones, a contribution of an additionally acting mesomechanic kinematic in fabric weaves is implied. Based on a degree of ondulation, it is possible to classify the enhancement of the material damping and determine the corresponding energy dissipation. The study provides valuable quantitative relations of the additional damping effect due to the mesomechanic kinematic. Compared to the unidirectionally reinforced material, plain weave enhances the material damping by 37…52%. The consideration of the findings contributes to a deeper understanding of the visco-elastic dynamic behavior of fabric-reinforced plastics and allows further applications in research, development, and industry.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Kastenmeier2023,

title = {Review of elasto-static models for three-dimensional analysis of thick-walled anisotropic tubes},

author = {A. Kastenmeier and M. Siegl and I. Ehrlich and N. Gebbeken},

doi = {10.1177/00219983231215863},

issn = {0021-9983},

year  = {2024},

date = {2024-03-01},

urldate = {2023-11-28},

journal = {Journal of Composite Materials},

volume = {58},

issue = {7},

pages = {923-951},

publisher = {SAGE Publications},

abstract = {Most shell or beam models of anisotropic tubes under bending have no validity for thick-walled structures. As a result, the need to develop three-dimensional formulations which allow a change in the stress, strain and displacement distributions across the radial component arises. Basic formulations on three-dimensional anisotropic elasticity were made either stress- or displacement-based by Lekhnitskii or Stroh on plates. Lekhnitskii also was the first to expand these analytical formulations to tubes under various loading conditions. This paper presents a review of the stress and strain analysis of tube models using three-dimensional anisotropic elasticity. The focus lies on layered structures, like fiber-reinforced plastics, under various bending loads, although the basic formulations and models regarding axisymmetric loads are briefly discussed. One section is also dedicated to the determination of an equivalent bending stiffness of tubes.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Pongratz2024,

title = {Test Setup for Investigating the Impact Behavior of Biaxially Prestressed Composite Laminates},

author = {C. Pongratz and J. Tix and J. Wolfrum and S. Gerke and I. Ehrlich and M. Brünig},

doi = {10.1007/s40799-024-00701-4},

issn = {1747-1567},

year  = {2024},

date = {2024-02-08},

urldate = {2024-02-08},

journal = {Exp Tech},

publisher = {Springer Science and Business Media LLC},

abstract = {Instrumented impact testing and compression-after-impact testing are important to adequately qualify material behavior and safely design composite structures. However, the stresses to which fiber-reinforced plastic components are typically subjected in practice are not considered in the impact test methods recommended in guidelines or standards. In this paper, a test setup for investigating the impact behavior of composite specimens under plane uniaxial and biaxial preloading is presented. For this purpose, a special test setup consisting of a biaxial testing machine and a specially designed drop-weight tower was developed. The design decisions were derived from existing guidelines and standards with the aim of inducing barely visible impact damage in laminated carbon fiber-reinforced plastic specimens. Several measurement systems have been integrated into the setup to allow comprehensive observation of the impact event and specimen behavior. A feasibility test was performed with biaxially prestressed carbon fiber-reinforced plastic specimens in comparison with unstressed reference tests. The compressive-tensile prestressing resulted in lower maximum contact forces, higher maximum deflections, higher residual deflections and a different damage pattern, which was investigated by light microscopic analysis. Finally, the functionality of the experimental setup is discussed, and the results seem to indicate that the test setup and parameters were properly chosen to investigate the effect of prestresses on the impacts behavior of composite structures, in particular for barely visible subsequent damages.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}