Vibration Characteristics of Rubber Vibration Isolators of Vehicle : Analysis of Nonlinear Vibration Response for Multiple-Degree-of-Freedom System

Previously we have already proposed the method of analytical response for one degree of freedom and for modeling rubber vibration isolator used in automobiles as a spring. In this paper, we describe a method of analytical response for two degrees of freedom as the first step to apply a multiple-degree-of-freedom system. This method expands the method based on an equivalent linear system using the restoring force model of power function type (PFT-ELS) which was thought to be easily applicable to a multiple-degree-of-freedom system. Using this method we determine the predominant frequency of the relative displacement of the rubber itself by using a period on each one of the hysteresis loops in relation to frequency and amplitude of response displacement. We carried out an experiment on vertical vibration when the vibration system was acted upon by random external force. We were able to verify the appropriateness and accuracy of this method by directly comparing the analytical results with the experimental results for the dynamic response of a system.