Elastic-plastic characterization of microstructures through pull-in 4 point bending test

This paper presents a simple design of gold MEMS, with a central test specimen undergoing tensile loading, for the experimental characterization of elastic-plastic behavior using electrostatic actuation. A kinematic model for the test microstructures is presented that relates the experimentally measured deflection in the test specimen to the developed axial and bending stress. Moreover, an elastic-plastic beam bending model is presented to analyze the development of plastic hinges in the central test specimen. The design of test microstructures allows us to achieve stress values higher than the yield stress of the gold specimen before the pull-in effect, thus allowing to analyze the effect of elastic-plastic behavior on the static deflection profile of the central test specimen under repeated loading. The actuation voltage-deflection tests under repeated loading, both in the elastic and elastic-plastic region, allowed to estimate the applied stress limit for the onset of plasticity in gold thin film based MEMS devices.