Vibroacoustics of composite housing for electrical motors

Abstract

This study is aimed at the specific practicable application of certain composite elements for housing of electrical motors. This article presents a novel analytical model for forced vibrations and vibroacoustic investigations of a laminated shell composed of two metallic layers with a polymeric interlayer. This material composition differs from classical sandwich materials due to the thickness-relations (thickness ratio of cover layer to the interlayer of about 20) as well as jump of stiffness between the single layers (ratio of about 20,000). The dynamic theory of cylindrical shells has been enhanced to include the vibroacoustic behaviour of the composite shell with polymeric interlayer. The results presented in this article include mode shapes and frequency of free vibrations as well as the forced vibrations of composite shell with polymeric interlayer and its monolithic counterpart. The damping values of this structural composition were found to exceed those of a corresponding monolithic metallic shell by a factor of over 100. Moreover, a number of dynamic and vibroacoustic finite element simulations were also carried out whereby close correlation between the analytical models and the numerical finite element results were achieved. Using this composite material, and its related models, a reduction of the transverse vibration amplitude by a factor of 10 compared to the monolithic material is obtained. The results of this article can be an effective tool for the vibroacoustic analysis and design of electrical motor housings.