The steady increase in computational power induces an equally steady increase in the complexity of the engineering models and associated computer codes. This particularly affects the modeling of the mechanical response of materials. Material behavior is nowadays modeled in the strongly nonlinear range by tak- ing into account finite strains, complex hysteresis effects, fracture phenomena and multiscale features. Progress in this field is of fundamental importance for many engineering disciplines, especially those concerned with material testing, safety, reliability and serviceability analyses...