TY - CONF A1 - Vöse, Markus A1 - Fedelich, Bernard T1 - Simulation of creep damage in a Cu polycrystal under multiaxial loading N2 - The stress States of components under Service conditions differ in general from the loading conditions that are routinely applied during material testing. When data that results, e.g., from uniaxial testing should be used for lifetime assessment, a good understanding of the failure behaviour in dependence of the stress state is necessary. For polycrystalline materials under high temperature loading, the development of creep damage is one important factor that limits a component’s lifetime. For cases where creep damage is related to the nucleation and growth of grain boundary cavities, the local normal stress acting on a grain boundary has been found to have a strong influence on the damage development. Hence, creep damage is usually localized along planes that lie perpendicular to the maximum principal tensile stress. T2 - CREEP 2015 - 13th International conference on creep and fracture of engineering materials and structures CY - Toulouse, France DA - 31.05.2015 PY - 2015 SP - 175 EP - 176 AN - OPUS4-33455 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Vöse, Markus A1 - Fedelich, Bernard ED - Maruyama, K. ED - Abe, F. ED - Igarashi, M. ED - Kishida, K. ED - Suzuki, M. ED - Yoshimi, K. T1 - Grain boundary cavitation under time-varying normal stresses N2 - In a polycrystal, the development of creep damage, especially for low extemal loads, is related to nucleation and difiüsive growth of cavities on the grain boundaries. For low stresses, the contribution to cavity growth by dislocation creep of the suirounding material can be neglected. However, grain boundaiy diffitsion is mainly driven by the local normal stiess acting on the grain boundaiy. Under creep conditions, even under a constant extemal load, an individual grain boundaiy generally experiences a time-varying normal stress, due to stress redistributions within the polycrystalline stiuctuie. Indeed, a constrained cavitating grain boundaiy is relieved, since matter is transported to and deposited in the grain boundaiy plane, which causes the adjoining giains to drill apart. A Simulation proceduie based on the use of complex holomoiphic fiinctions for solving the diffiision problem has been used to investigate multiple cavity growth on a grain boundaiy subjected to a constant normal stress. A simplified model has been developed to describe the cavitation behaviour observed in the simulations. Finally, the analysis of cavitation simulations with time-vaiying nomial stresses, including the cases with veiy low or negative stresses, has been used to extend the simplified cavitation model to more general normal stiess time profiles. T2 - 12th International Conference on Creep and Fracture of Engineering Materials and Structures CY - Kyoto, Japan DA - 27.05.2012 KW - Creep damage KW - Grain boundary diffusion KW - Cavitation KW - Simulation KW - Evolution equations PY - 2012 SP - 1 EP - 4 AN - OPUS4-27544 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -