Effect of specimen size on natural vibration of open hole copper/glassreinforced epoxy laminate composites

Abstract

Composite material has attractive applications in electronic devices; glass fiber/copper reinforced epoxy is one completive material in Micro-Electro-Mechanical-Systems (MEMS). Upon operation, mechanical vibration arises from the electrical current fluctuations causing damage and consequently affect its performance. On the other hand, size effect in the strength of a material is referred to as a decrease in the nominal strength of a scaled open hole structure. Therefore, this work aims to study the scaling phenomenon concerning dynamic and vibration for a composite structure used in MEMS devices. At this end, a matrix of specimens with 2, 4, 6, 8, 10, and 12 mm diameter circular holes of copper/laminated glass fiber reinforced epoxy plated have subjected to simple vibration test modal analysis using the free-fallen hammer. A simple finite element model is built to obtain different shape modes which revealed the different mode shapes and Mises stress effect regions, moreover the frequency factor at each mode. The response of the material to free vibration has given different trends with holes. With increasing specimen size, the natural frequencies increase, this is opposite results when increasing the static load. The Finite element results are in good agreement with the published ones. The cantilever boundary condition is reported to be the most satisfied for the lower two modes.