Continuum mechanics may be applied when the microscopic scale, where the deformation behavior of a material is ultimately determined, is well separated from the macroscopic scale of interest. I am interested in extending continuum methods to mesoscopic scales, where either the stochastic nature of the microstructure becomes important, extreme values rather than average values determine materials behavior, or where collective effects of microstructural objects dominate. One of the least well understood mesoscopic phenomenon is actually metal plasticity, especially work hardening, which results from a complex mutual interaction of crystal dislocations and their interaction with other crystal defects. Other mesoscopic phenomena which I am interested in are the failure behavior of brittle porous materials and the deformation of granular materials. With my research I seek to integrate these mesoscopic effects in macroscopic material models in order in increase the scope of the powerful numerical methods of strength of materials.