The mechanical stability of silicon MEMS dies is strongly influenced by the microfabrication processes, especially grinding, dicing and etching, which leave characteristic damage (defects, cracks, dislocations...) in the substrate material. Specially designed mechanical tests are used to assess the resistance of micro-structures to monotonic and cyclic loading. We report on the development progress of a micromechanical test bench for reliability assessment of microstructures in 2-, 3- and 4-point bending configurations. Strain distributions and defects in micron-sized silicon devices can be investigated by in-situ testing in combination with high-resolution x-ray diffraction measurements for experimentally assessing the strain distribution.