A Novel Semi-active Fluid Mount using a Multi-layer Piezoelectric Beam

Abstract

Passive fluid mounts have been in use for the purpose of cabin noise and vibration reduction in the automotive and the aerospace industry for many years. Cabin noise and vibration isolation are provided at a frequency coined “notch frequency”. The design location of the notch frequency depends on the application, but in most applications, it is designed to coincide with the longest period of constant speed. To obtain the greatest reduction in cabin noise and vibration at any desired frequency, the notch frequency needs to be as close to that desired frequency as possible. Unfortunately, the conventional passive fluid mounts have some limitations. Firstly, due to tolerances on all the fluid mount dimensions, elastomer material property variations, and variation in elastomer molding processes, the notch frequency never ends up at the right location on the first manufacturing pass. To reduce the fluid mount notch frequency tuning cycle time, a new fluid mount design is proposed. This new design consists of a conventional single-pumper fluid mount and a 3-layer piezoelectric cantilever beam as a component that provides us a variable bottom chamber volumetric stiffness and in consequence a fluid mount with a tunable notch frequency. In this paper, the new design concept, and its mathematical model and simulation results will be presented.