Thermal instability of a layered rectangular viscoelastic prism under high-frequency compressive loading

Abstract

The thermal instability of a rectangular prism under vibrational heating is studied solving a coupled problem of thermoviscoelasticity and using finite-element modeling. The prism has copper and polyethylene or polymethylmethacrylate layers and undergoes high-frequency mechanical or kinematic compression. It is established that in the case of polyethylene, thermal instability occurs under mechanical loading and does not occur under kinematic loading. In the case of polymethylmethacrylate, thermal instability occurs under both kinds of loading. This is because of the increase in the shear and bulk loss compliances with temperature for each of the polymers. At the transformation temperature, shear dissipation goes over into bulk dissipation, which is predominant in rather thin polymeric layers. Dynamicity influences the critical loads both qualitatively and quantitatively