TY - CONF A1 - Trappe, Volker A1 - Kraus, David T1 - Thermo-mechanical fatigue of glass fiber reinforced polymer N2 - Glass fiber reinforced polymer (GFRP) materials in practical applications have to endure cyclic mechanical loading in a wide temperature range (e.g. aircraft applications, automotive, wind turbine blades). In this study the static strength and fatigue behavior of GFRP was investigated in a temperature range from 213 K to 343 K. Therefor the coefficients of thermal expansion of the composite as well as the matrix are measured in this temperature interval. The inverse laminate theory was extended and used to calculate the inter fiber-failure effort for a virtual UD-layer according to the layer wise strength approach. The experimentally determined results are compared with the micro-mechanical model according to Krimmer, which has been enhanced to include the effect of temperature and fiber-perpendicular failure modes. A correlation between matrix effort, the dilatational strain energy of the matrix and the damage state of the specimen is demonstrated. It is shown that a fatigue life assessment can be performed with the aid of a temperature-independent master fatigue curve, as it was similar done for the fatigue behavior of CFRP and GFRP to very high load cycles at room temperature. T2 - ICFC8 - The 8th International Conference on the Fatigue of Composites CY - Online meeting DA - 23.06.2021 KW - Glass fibre reinforced plastics KW - Fatigue KW - Thermo-mechanical-loading PY - 2021 AN - OPUS4-52910 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kraus, David A1 - Trappe, Volker T1 - Transverse damage in glass fiber reinforced polymer under thermo-mechanical loading JF - Composites Part C N2 - In this study, the thermomechanical damage behavior of a glass fiber reinforced polymer material is investigated. The coefficients of thermal expansion of the composite as well as the matrix are measured in a wide temperature range. Quasi-static experiments with neat resin, unidirectional and multidirectional laminates are performed as well as fatigue experiments in a temperature range from 213 K to 343 K. This study focusses on the matrix damage due to fiber-parallel loading. A correlation between matrix effort, the dilatational strain energy of the matrix and the damage state of the specimen is demonstrated. It is shown that a fatigue life assessment can be performed with the aid of a temperature-independent master fatigue curve. KW - Composite KW - Glass fiber reinforced polymer KW - Thermo-mechanics KW - Fatigue KW - Damage KW - Temperature PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-527462 DO - https://doi.org/10.1016/j.jcomc.2021.100147 SN - 2666-6820 VL - 5 SP - 100147 PB - Elsevier B.V. AN - OPUS4-52746 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Trappe, Volker A1 - Hickmann, Stefan A1 - Müller, Alexander T1 - Infinite life of CFRP evaluated non-destructively with X-ray-refraction topography in-situ mechanical loading N2 - Carbon Fibre Reinforced Plastics (CFRP) are more and more used in modern civil aircrafts. These days the whole fuselage is made of this material (B787; A350). Due to strict certification standards the normal in-service loading gives a low stress level compared to the static and even the fatigue strength of the material. Hence CFRP are assumed to have an infinite life. To evaluate this assumption, fatigue tests on CFRP-specimens were performed up to 108 load cycles and the first inter-fibre failure was evaluated non-destructively by accompanying X-ray-refraction topography. A tensile testing machine was integrated in a small angle X-ray scattering (SAXS) setup. X-ray refraction topography was performed while the CFRP-samples were tensile loaded. This non-destructive technique enables the detection of micro-cracking and inter-fibre failure especially for CFRP. For Glass Fibre Reinforced Plastic (GFRP) X-ray refraction and in-situ loading has already been successfully used. The increase of inner surfaces due to inter fibre failure was measured as a function of the stress state. Fatigue tests were performed at and below the limit of inter-fibre failure strength. State of the art is to assume the failure of the samples under cyclic loading as the fatigue life. Accompanying non-destructive X-ray refraction measurements reflects the damage state and enables to trace its evolution even if the total failure of the specimens does not occur. This investigation technique is of high interest to give the engineer a design value of infinite life which is practically often reached due to knock down factors of certification standards. Finally the infinite life was found for cyclic fatigue loaded CFRP-samples even under high inter fibre transverse and shear loading investigated up to 108 load cycles. T2 - 19th World Conference on Non-Destructive Testing CY - Munich, Germany DA - 13.06.2016 KW - CFRP KW - NDT KW - Fatigue KW - Damage evolution PY - 2016 AN - OPUS4-37567 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Trappe, Volker A1 - Basan, Ricardo T1 - Fatigue life evaluation of spar cap materials by four point bending test on width-tapered specimens N2 - The presented research project focuses on an effective method to evaluate the fatigue strength of thick unidirectional laminates to be applied in spar caps. Therefore, a width-tapered bending specimen was developed for a four point loading set up. Static and fatigue loading was performed with the load ratio of R=-1. The complex stress state was investigated numerically with a finite element analysis. Finally, the concept was proven experimentally on specimens made of pultruded fibre rods. The fatigue behaviour of continuous tapered width by water jet cutting was compared to discrete tapering by rod-drop. T2 - 20th International Conference on Composite Materials CY - Copenhagen, Denmark DA - 19.07.2015 KW - Fatigue KW - CFRP KW - Pultruded fibre rods KW - Spar cap design PY - 2015 AN - OPUS4-38781 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Trappe, Volker A1 - Basan, Ricardo T1 - Fatigue life evaluation of spar cap materials by four point bending test on width-tapered specimensa T2 - ICCM 20 N2 - The presented research project focuses on an effective method to evaluate the fatigue strength of thick unidirectional laminates to be applied in spar caps. Therefore, a width-tapered bending specimen was developed for a four point loading set up. Static and fatigue loading was performed with the load ratio of R=-1. The complex stress state was investigated numerically with a finite element analysis. Finally, the concept was proven experimentally on specimens made of pultruded fibre rods. The fatigue behaviour of continuous tapered width by water jet cutting was compared to discrete tapering by rod-drop. T2 - 20th International Conference on Composite Materials CY - Copenhagen, Denmark DA - 19.07.2015 KW - Fatigue KW - Pultruded fibre rods KW - CFRP KW - Four point bending test KW - Spar cap design PY - 2015 UR - http://iccm20.org/fullpapers/file?f=WM39KAy5ME VL - 2015 SP - Paper 150701-2549 PB - ICCM20 CY - Copenhagen AN - OPUS4-38783 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Trappe, Volker A1 - Müller, Alexander A1 - Hickmann, Stefan T1 - Infinite life of CFRP evaluated non-destructively with X-ray-refraction topography in-situ mechanical loading T2 - WCNDT-Proceedings 2016 N2 - Carbon Fibre Reinforced Plastics (CFRP) are more and more used in modern civil aircrafts. These days the whole fuselage is made of this material (B787; A350). Due to strict certification standards the normal in-service loading gives a low stress level compared to the static and even the fatigue strength of the material. Hence CFRP are assumed to have an infinite life. To evaluate this assumption, fatigue tests on CFRP-specimens were performed up to 108 load cycles and the first inter-fibre failure was evaluated non-destructively by accompanying Xray-refraction topography. A tensile testing machine was integrated in a small angle X-ray scattering (SAXS) setup. X-ray refraction topography was performed while the CFRP samples were tensile loaded. This non-destructive technique enables the detection of micro-cracking and inter-fibre failure especially for CFRP. For Glass Fibre Reinforced Plastic (GFRP) X-ray refraction and in-situ loading has already been successfully used. The increase of inner surfaces due to inter fibre failure was measured as a function of the stress state. Fatigue tests were performed at and below the limit of inter-fibre failure strength. State of the art is to assume the failure of the samples under cyclic loading as the fatigue life. Accompanying non-destructive X-ray refraction measurements reflects the damage state and enables to trace its evolution even if the total failure of the specimens does not occur. This investigation technique is of high interest to give the engineer a design value of infinite life which is practically often reached due to knock down factors of certification standards. Finally the infinite life was found for cyclic fatigue loaded CFRP-samples even under high inter fibre transverse and shear loading investigated up to 108 load cycles. T2 - 19th World Conference on Non-Destructive Testing CY - Munich, Germany DA - 13.06.2016 KW - CFRP KW - NDT KW - Fatigue KW - Damage evolution PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-375015 UR - https://www.ndt.net/?id=19360 SN - 978-3-940283-78-8 VL - 2016 SP - 1 EP - 9 PB - DGZFP CY - Berlin AN - OPUS4-37501 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kraus, David A1 - Trappe, Volker T1 - Cyclic fatigue behavior of glass fiber reinforced epoxy resin at ambient and elevated temperatures T2 - ECCM18 - 18th European conference on composite materials (proceedings) N2 - The fatigue behavior of ±45° glass fiber reinforced epoxy resin under cyclic mechanical and constant thermal loading is investigated in this study. Tests at three different temperature levels in the range 296 K to 343 K have been performed in order to create S-N curves for each temperature level. The specimen damage is measured in-situ using optical grayscale analysis. The characteristic damage state (CDS) is evaluated for each specimen. It is shown that the point of CDS is suitable as a failure criterion to compare the resulting S-N curves. With micromechanical formulations, the temperature-dependent matrix effort is calculated for each stress-temperature level. In terms of matrix effort, the longest fatigue life is reached at high temperatures, while, in terms of stress, the lowest fatigue life is reached at the highest temperatures. T2 - ECCM18 - 18th European conference on composite materials CY - Athens, Greece DA - 24.06.2018 KW - Composite KW - Fatigue KW - Thermomechanics KW - Residual stresses KW - Temperature PY - 2018 SP - 1 EP - 7 PB - European society for composite materials AN - OPUS4-45338 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Müller, Alexander A1 - Trappe, Volker A1 - Hickmann, Stefan A1 - Ortwein, H.-P ED - Christ, Hans-Jürgen T1 - Investigation of the infinite life of fibre-reinforced plastics using X-ray refraction topography for the in-situ, nondestructive evaluation of micro-structural degradation processes during cyclic fatigue loading T2 - Fatigue of Materials at Very High Numbers of Loading Cycles N2 - The described investigation of carbon-fibre-reinforced plastics (CFRP) documents that damage evolution can be observed by means of X-ray refractography. Comparative investigations with synchrotron technique on CFRP and grey-scale analysis on glass fibre-reinforced-plastics (GFRP) confirm these results. Moreover it was found that the fracture mechanical properties of the matrix system influence damage nucleation and propagation in the laminate during static and fatigue loads. Single-step fatigue tests were carried out on Laminates with RIM135 and LY556 matrix systems made from non-crimped fabric (NCF) or twill weave in different fibre orientations. The damage to the LY556 laminates was characterized by laminate cracks growing rapidly over the whole specimen width, whereas the damage on the RIM135 laminates was characterized by an earlier onset of micro-cracking followed by laminate cracks. The specimens were fatigued up to 108 (very high cycle fatigue (VHCF) regime) load cycles. S-N-curves of damage initiation were drawn and boundaries were identified for endurance within the VHCF regime. A phenomenology based model focusing on matrix stress was applied to reproduce the first inter-fibre failure (IFF) under static and fatigue loads. KW - Carbon fibre-reinforced-plastics KW - Fatigue KW - Damage evolution KW - X-ray refractography KW - Very high cycle fatigue PY - 2018 SN - 978-3-658-24531-3 DO - https://doi.org/10.1007/978-3-658-24531-3 VL - 2018 SP - 417 EP - 439 PB - Springer Spektrum CY - Wiesbaden ET - 1. Auflage AN - OPUS4-50096 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Trappe, Volker A1 - Kraus, David A1 - Kübler, Stefan A1 - Eisermann, René T1 - Multiaxial fatigue damage of glass fiber reinforced polymers N2 - Fiber reinforced polymers (FRPs) are a well established material in lightweight applications, e.g. in automotive, aerospace or wind energy. The FRP components are subjected to multiaxial mechanical as well as hygrothermal loads. Common operation temperatures are in the range of 213 K and 373 K (-60 °C and 100 °C) at a relative humidity of 10% to 90%. In spacecraft applications, the environmental conditions are even more extreme. However, the correlation between multiaxial mechanical loading and harsh environment conditions have to-date not been investigated in detail. The project aims to investigate the fatigue behavior of FRPs dependent on multiaxial mechanical loading, temperature, and humidity. Extensive experimental testing is performed on flat plate and cylindrical tube specimens, accompanied by numerical and analytical calculations. T2 - 24. Nationales SAMPE Symposium CY - Dresden, Germany DA - 06.02.2019 KW - Composite KW - Fatigue KW - Thermomechanics KW - Distributed fiber optic sensors PY - 2019 AN - OPUS4-47335 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kraus, David A1 - Trappe, Volker T1 - Impact of thermal loads on the damage onset of fiber reinforced plastics T2 - ICCM21 - 21th International conference on composite materials (Proceedings) N2 - In this study, quasi-static material tests on unidirectional and multi-angle glass fiber reinforced epoxy laminates at ambient temperatures from -213 K to 353 K (-60 °C to +80 °C) are performed. In addition, neat resin is investigated under tension and compression loads at different temperatures. The coefficient of thermal expansion is determined for neat resin and unidirectional reinforced specimens. The dependence of the resin’s thermomechanical properties on the ambient temperature is shown. The point of damage onset at which first cracks appear within the matrix under quasi-static loading is investigated by means of optical grey scale analysis. The correlation between damage onset and effective matrix stress at different ambient temperatures is identified. An approach for the calculation of thermomechanical loads and the prediction of the damage onset by means of inverse calculations is presented. The impact of the strain blocking effect of the matrix is considered as well as residual thermal stresses due to curing and resin shrinkage. T2 - ICCM21 - 21th International conference on composite materials CY - Xi'an, China DA - 20.08.2017 KW - Fatigue KW - Composite KW - Thermomechanics KW - Fiber reinforced plastics KW - Damage onset PY - 2017 SP - 1 EP - 12 AN - OPUS4-42075 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -