TY - CONF A1 - Kraus, David A1 - Trappe, Volker T1 - Impact of thermal loads on the damage onset of fiber reinforced plastics 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 - International Conference of Composite Materials 21, ICCM21 CY - Xi'an, China DA - 20.08.2017 KW - Fatigue KW - Composite KW - Thermomechanics KW - Fiber reinforced plastics PY - 2017 AN - OPUS4-42074 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Boller, Ch. A1 - Mueller, Bernd R. A1 - Heckel, Thomas A1 - Starke, P. A1 - Gohlke, Daniel A1 - Venkat, R. S. A1 - Bruno, Giovanni T1 - Nonlinearities based inverse approach for the characterisation of the damage evaluation process in very high cycle fatigued CFRP specimens N2 - This paper focuses on the aspect on how damage evolution processes in composite materials and structures including matrix fracture, delamination, fibre-matrix debonding, and fibre fracture can be detected by taking advantage of the material’s inherit mechanical properties. These properties can be described on the basis of non-linear mechanical phenomena measurable as an inert frequency response signal. The approach is proposed as a means for residual life structural assessment specifically in the context of VHCF. T2 - The Seventh International Conference on Very High Cycle Fatigue - VHCF7 CY - Dresden, Germany DA - 03.07.2017 KW - Composite materials KW - Damage KW - Non-destructive testing KW - Fatigue KW - Structural simulation KW - Non-linear vibration PY - 2017 VL - 2017 SP - 1 EP - 8 PB - DVM AN - OPUS4-41102 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pfennig, Anja A1 - Kranzmann, Axel T1 - Potential of martensitic stainless steel X5CrNiCuNb 16-4 as pipe steel in corrosive CCS environment N2 - Pipe steels suitable for carbon capture and storage technology (CCS) require resistance against the corrosive environment of a potential CCS-site (heat, pressure, salinity of the aquifer, CO2-partial pressure). X5CrNiCuNb16-4 has been proven to be sufficient resistant in corrosive environments, but shows rather unusual corrosion behaviour in CCS environment. Therefore differently heat treated coupons of 1.4542 were kept at T=60 °C and ambient pressure as well as p=100 bar for 700 h - 8000 h in an a) water saturated supercritical CO2 and b) CO2-saturated synthetic aquifer environment similar to on-shore CCS-sites in the Northern German Basin. Additionally fatigue tests were performed via push-pull tests with a series of 30 specimens was tested at stress amplitudes between 150 MPa and 500 MPa (sinusoidal dynamic test loads, R=-1; resonant frequency ~ 30 Hz). Best corrosion resistance in the liquid phase is achieved via normalizing prior to exposure and hardening+tempering at 670 °C leads to lowest corrosion rates in the supercritical phase. With no regard to atmosphere discontinuously ellipsoidal surface corrosion regions appear after exposure of 4000 h and more. The endurance limit of X5CrNiCuNb16-4 measured in air is reduced by more than 50% when exposed to CCS environment (maximum number of cycles (10 x 106) at a stress amplitude of 150 MPa) The scatter range TN = 1:34 is disproportionately large contributing to an overall unusual corrosion behaviour. KW - Corrosion KW - CCS KW - Carbon storage KW - Aquifer KW - Heat treatment KW - Fatigue KW - Endurance limit PY - 2017 DO - https://doi.org/10.18178/ijesd.2017.8.7.998 SN - 2010-0264 VL - 8 IS - 7 SP - 466 EP - 473 AN - OPUS4-41863 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krütt, Enno A1 - Weise, Frank A1 - Meng, Birgit ED - Ye, G. ED - Yuan, Y. ED - Romero Rodriguez, C. ED - Zhang, H. ED - Savija, B. T1 - Fatigue induced degradation in pavement concrete and its effect on the alkali-silica reaction N2 - In recent years the German motorway network has seen an increase in the occurrence of damage to concrete road surfaces that can be attributed to the alkali-silica reaction (ASR). In view of the often drastically reduced service life of road surfaces due to ASR, research activity in this field has notably increased. Alongside preventative measures in concrete technology i.e. the usage of low-alkali cements, the main research focus up to now has been on the development of performance-oriented testing procedures for ASR prevention. The effects of mechanicallyinduced damage resulting from cyclic traffic and climatic loading have previously not been taken into consideration. The assessment of the myriad degradation and transport processes necessary for an understanding of these effects requires close interaction between experiments and corresponding multi-scale models. This contribution is focused on the experiments utilizing innovative testing techniques. The research is founded on a series of fatigue tests performed on large-scale beams with simultaneous tracking of the degradation process using non-destructive evaluation methods. Subsequently, smaller test specimens were extracted from the predamaged beams for further experiments. These experiments included investigation of the influence of fatigue-induced cracks on moisture and alkali transport. Subsequent storage of the small-scale test specimens, with and without cyclic pre-damage, in an ASR-conducive environment then provided initial findings on the influence of fatigue-induced degradation on the ASR. The results show that the degradation process can be well observed with the test Setup developed for the fatigue experiments. Further, a small but noticeable increase of mass Transport due to fatigue-induced degradation was measured, which correspondingly indicated an increased ASR damage potential. T2 - 4th International Conference on Service Life Design for Infrastructures (SLD4) CY - Delft, The Netherlands DA - 27.08.2018 KW - Fatigue KW - Pavement KW - ASR KW - Concrete PY - 2018 SN - 978-2-35158-213-8 SP - 112 EP - 121 PB - RILEM Publication S.A.R.L. CY - Paris, France AN - OPUS4-46197 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krütt, Enno A1 - Weise, Frank A1 - Meng, Birgit T1 - Fatigue induced degradation in pavement concrete and its effect on the alkali-silica-reaction N2 - In recent years the German motorway network has seen an increase in the occurrence of damage to concrete road surfaces that can be attributed to the alkali-silica reaction (ASR). In view of the often drastically reduced service life of road surfaces due to ASR, research activity in this field has notably increased. Alongside preventative measures in concrete technology i.e. the usage of low-alkali cements, the main research focus up to now has been on the development of performance-oriented testing procedures for ASR prevention. The effects of mechanicallyinduced damage resulting from cyclic traffic and climatic loading have previously not been taken into consideration. The assessment of the myriad degradation and transport processes necessary for an understanding of these effects requires close interaction between experiments and corresponding multi-scale models. This contribution is focused on the experiments utilizing innovative testing techniques. The research is founded on a series of fatigue tests performed on large-scale beams with simultaneous tracking of the degradation process using non-destructive evaluation methods. Subsequently, smaller test specimens were extracted from the predamaged beams for further experiments. These experiments included investigation of the influence of fatigue-induced cracks on moisture and alkali transport. Subsequent storage of the small-scale test specimens, with and without cyclic pre-damage, in an ASR-conducive environment then provided initial findings on the influence of fatigue-induced degradation on the ASR. The results show that the degradation process can be well observed with the test Setup developed for the fatigue experiments. Further, a small but noticeable increase of mass Transport due to fatigue-induced degradation was measured, which correspondingly indicated an increased ASR damage potential. T2 - 4th International Conference on Service Life Design for Infrastructures (SLD4) CY - Delft, The Netherlands DA - 27.08.2018 KW - Fatigue KW - Pavement KW - ASR KW - Concrete PY - 2018 AN - OPUS4-46199 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Olbricht, Jürgen A1 - Jürgens, Maria A1 - Agudo Jácome, Leonardo A1 - Nolze, Gert A1 - Roohbakhshan, Farshad A1 - Fedelich, Bernard A1 - Skrotzki, Birgit T1 - Cyclic loading and creep-fatigue performance of P92 N2 - 9-12% Cr ferritic-martensitic stainless steels are widely used as high temperature construction materials in power plants due to their excellent creep and oxidation resistance. The growing share of renewable energy sources in power generation forces many of these plants into more flexible operation with frequent load shifts or shutdowns. These cyclic operation profiles constitute a major lifetime issue. The present contribution reports on current findings obtained in a multidisciplinary project which combines cyclic mechanical and cyclic oxidation testing of different 9-12% Cr grades with detailed microstructural analyses. Mechanical analyses are carried out on P92 and P91 steel grades to give an overview of softening phenomena and lifetimes obtained in isothermal cyclic loading (low cycle fatigue, LCF), non-isothermal cyclic loading (thermo-mechanical fatigue, TMF), and service-like combinations of creep and fatigue periods. Complementary microstructural investigations by scanning and transmission electron microscopy plus EBSD are used for phase identification, substrate/oxide interface characterization and quantification of the microstructure evolution under cyclic conditions. T2 - 44th MPA-Seminar CY - Leinfelden/Stuttgart, Germany DA - 17.10.2018 KW - Ferritic-martensitic steels KW - Fatigue KW - Creep-fatigue PY - 2018 AN - OPUS4-47116 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rehmer, Birgit A1 - Skrotzki, Birgit A1 - Glaubitz, Steffen T1 - Influence of casting skin on fatigue lifetime of ferritic ductile cast iron N2 - The fatigue behaviour of cast iron is usually investigated on machined specimens. Components of cast iron, however, have a casting skin; therefore the investigation of the influence of the casting skin on the lifetime is of interest. To study this influence isothermal fatigue tests were carried out on heat-resisting spheroidal graphite cast iron EN GJS SiMo 4.05 in 4–point-bending set-up at 400 °C. Specimens with and without casting skin were investigated comparatively. The number of cycles to failure was significantly lower for specimens with casting skin. Metallographic investigations underline the reduction of lifetime caused by casting skin. KW - Cast iron KW - Casting skin KW - Fatigue KW - Lifetime PY - 2017 SN - 0025-5300 VL - 59 IS - 1 SP - 5 EP - 10 PB - Carl Hanser Verlag CY - München AN - OPUS4-38929 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kindrachuk, Vitaliy A1 - Fedelich, Bernard A1 - Rehmer, Birgit A1 - Peter, Frauke T1 - Computational methods for lifetime prediction of metallic components under high-temperature fatigue N2 - The issue of service life prediction of hot metallic components subjected to cyclic loadings is addressed. Two classes of lifetime models are considered, namely, the incremental lifetime rules and the parametric models governed by the fracture mechanics concept. Examples of application to an austenitic cast iron are presented. In addition, computational techniques to accelerate the time integration of the incremental models throughout the fatigue loading history are discussed. They efficiently solve problems where a stabilized response of a component is not observed, for example due to the plastic strain which is no longer completely reversed and accumulates throughout the fatigue history. The performance of such an accelerated Integration technique is demonstrated for a finite element simulation of a viscoplastic solid under repeating loading–unloading cycles. KW - Fatigue KW - Incremental lifetime models KW - Finite element analysis PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-481215 UR - https://www.mdpi.com/2075-4701/9/4/390 DO - https://doi.org/10.3390/met9040390 SN - 2075-4701 VL - 9 IS - 4 SP - 390, 1 EP - 24 PB - mdpi CY - Basel, Switzerland AN - OPUS4-48121 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ratkovac, Mirjana A1 - Gerards-Wünsche, Paul A1 - Thiele, Marc A1 - Brackrock, Daniel A1 - Stamm, Michael T1 - Detection and monitoring of the fatigue crack growth on welds – Application-oriented use of NDT methods N2 - Early detection of fatigue cracks and accurate measurements of the crack growth play an important role in the maintenance and repair strategies of steel structures exposed to cyclic loads during their service life. Observation of welded connections is especially of high relevance due to their higher susceptibility to fatigue damage. The aim of this contribution was to monitor fatigue crack growth in thick welded specimens during fatigue tests as holistically as possible, by implementing multiple NDT methods simultaneously in order to record the crack initiation and propagation until the final fracture. In addition to well-known methods such as strain gauges, thermography, and ultrasound, the crack luminescence method developed at the Bundesanstalt für Materialforschung und -prüfung (BAM), which makes cracks on the surface particularly visible, was also used. For data acquisition, a first data fusion concept was developed and applied in order to synchronize the data of the different methods and to evaluate them to a large extent automatically. The resulting database can ultimately also be used to access, view, and analyze the experimental data for various NDT methods. During the conducted fatigue tests, the simultaneous measurements of the same cracking process enabled a comprehensive comparison of the methods, highlighting their individual strengths and limitations. More importantly, they showed how a synergetic combination of different NDT methods can be beneficial for implementation in large-scale fatigue testing but also in monitoring and inspection programs of in-service structures - such as the support structures of offshore wind turbines. T2 - Fatigue Design 2023 (FatDes 2023) CY - Senlis, France DA - 29.11.2023 KW - Fatigue KW - Welded KW - NDT KW - Crack growth PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-600238 DO - https://doi.org/10.1016/j.prostr.2024.03.062 VL - 57 SP - 560 EP - 568 PB - Elsevier B.V. AN - OPUS4-60023 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kindrachuk, Vitaliy A1 - Unger, Jörg F. T1 - A Multi-scale temporal integration scheme for viscoplatic solids subjected to fatigue deterioration N2 - Using a continuum mechanics framework for lifetime prediction requires numerical integration of evolving damage until the onset of failure. The primary challenge for the simulation of structural fatigue failure is caused by the enormous computational costs due to cycle by cycle temporal integration throughout the whole loading history, which is in the order of 10^3 - 10^7 cycles. As a consequence, most approaches circumvent this problem and use an empirical method such as Wöhler curves. They are well suited for approximation of the lifetime, but they are not capable to capture a realistic degradation of the material with a redistribution of the stresses. The main objective of the paper is to provide a technique for the long time response of a finite element (FE) model while reducing computational costs. A multi-scale temporal integration scheme is proposed, which adapts the conventional FE method for realistic modeling of deterioration in a structure subjected to cyclic loading. For a particular case of two-scale temporal homogenization, the displacement field is assumed to satisfy scale separation: a short time scale arises from the oscillatory loading and a long time scale is due to the slow response relating to yielding and damage evolution. The original boundary value Problem (BVP) is approximated by the time-Independent BVPs on the short time scale. Alternation of the displacement field on the long time scale is correlated with the damage evolution by means of the adaptive cycle jump method. The significant acceleration of FE simulations is demonstrated for a constitutive damage model where the progressive damage accumulation under fatigue loading is driven by viscoplastic deformation. T2 - ECCOMAS 2016 CY - Crete, Greece DA - June 5th KW - Fatigue PY - 2016 AN - OPUS4-38654 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -