A multiscale high-cycle fatigue-damage model for the stiffness degradation of fiber-reinforced materials based on a mixed variational framework

Under fatigue-loading, short-fiber reinforced thermoplastic materials typically show a progressive degradation of the stiffness tensor. The prior to failure is primary interest from an engineering perspective, as it determines when fatigue cracks nucleate. Efficient modeling this stage allows engineer monitor fatigue-process and design criteria which ensure safe application component under investigation. We propose multiscale model for in based on resolving fiber microstructure. For start, we specific fatigue-damage matrix, composite arises rigorous homogenization procedure. matrix rather special, its convex nature precludes localization, permits well-defined upscaling, thus well-adapted phase stable loading. demonstrate capabilities full-field by comparing predictions fully resolved microstructures experimental data. Furthermore, introduce associated model-order reduction strategy enable component-scale simulations local With mind upon implicit discretization time, transform minimization incremental potential into equivalent mixed formulation, combines two attractive features. More precisely, order reduction, formulation precomputing all necessary quantities advance, yet, retains well-posedness process. study characteristics technique, scale. Compared similar approaches, proposed leads improvements runtime more than magnitude. • use composites. resolve structure micro-scale. matrix. well-posed fits well with (MOR). mixed-formulation MOR quantities.