Finite Element Simulation of Accelerated Stress Testing and Damage Detection for Micro and Nano Structures Using Surface Acoustic Waves (SAWs)

The application demands and advances in micro-/nano-electronics has led to the advent of extremely small integral 1D, 2D or 3D functional elements and these new structures need to be assessed for thermo-mechanical reliability, but this topic is not addressed much in the literature. These structures are so small and delicate that pose a big challenge for handling without damaging, stress loading and degradation monitoring and, hence, demand new approaches to mechanical loading that are specimen-centered, size compliant in loading and highly sensitive to degradation evolution. In this paper, we propose a novel approach to the task of ultra-high cycle fatigue (UHCF) test of micro-/nano-scale objects utilizing surface acoustic waves (SAWs) both for resonant stress loading and degradation monitoring. The resonant SAW based UHCF tester device is equipped with an optical probe to visualize loading surface waves. For simulations of the fatigue tester device, we used a 2D finite element model (FEM) and, with the FEM plus COM approach introduced and employed in previous papers, the electrical admittance resonant peak frequency of the SAW device from simulation was only 5% different from the measurement reported in another paper for the same SAW structure.