Keynote: Simulation and Test Vibration - Nonlinear Dynamic Effects in Vibration Durability of Electronic Systems

This study explores the influence of nonlinear dynamic phenomena on damage accumulation in power electronics under vibration excitation. Two interesting experimental studies are presented where nonlinear damage accumulation is significant: (i) combined vibration and temperature excursions; and (ii) simultaneous multi-axial vibration. These situations are extremely important to modern power electronic assemblies because of the harsh environments where they are deployed in many applications. The first example shows the role that temperature and cyclic changes in temperature play on vibration damage accumulation rate. The nonlinearities arise from temperature-induced changes in the material properties and interactions between the thermo-mechanical stresses and vibration induced stresses. In the second example, heavy tall electronic components are found to experience significant nonlinear amplification of vibration induced stresses and damage when they are excited simultaneously along two orthogonal axes as opposed to a single axis at a time. Results demonstrate that linearized approximations of vibration induced failures can lead to highly misleading and non-conservative predictions of time to failure. Both examples raise serious questions about the adequacy of current methods for testing the reliability of power electronics.