Dynamic modeling and simulation of a two-stage series-parallel vibration isolation system

Introduction

Nowadays, with the development of the modern industry, when all kinds of production machinery and transportation machinery are toward high speed and high efficiency, more and more emphasis is laid on the noise and vibration control of them at the same time. A large amount of effort has been invested into the improvement of the technology of noise and vibration reduction and containment.¹

A two-stage vibration isolation system composed of three substructures is now widely used in various industrial fields. There are two kinds of two-stage isolation systems. One is defined as a two-stage series vibration isolation system (shown in Figure 1) and the other one is defined as a two-stage series-parallel vibration isolation system (shown in Figure 2). In a two-stage series system, substructure C as the vibration source is mounted on the substructure B and through it connected to substructure A (receiver). In a two-stage series-parallel system, substructure C is connected to both substructures A and B. And this article will focus on the series-parallel vibration isolation system.

Figure 1.

Two-stage series isolation system.

[Figure omitted. See PDF]

Figure 2.

Two-stage series-parallel isolation system.

[Figure omitted. See PDF]

Actually, at present, when the researchers analyze the vibration transfer characteristics of a system, the lumped mass method is usually applied. However, in a lumped mass model, the stiffness of the springs is a definite value, which is greatly different from an actual complex structure. Therefore, in this article, the dynamic modeling of a two-stage series-parallel vibration isolation system is finished using frequency response function (FRF)-based substructuring method. The FRF-based substructuring method has already been studied by some researchers.

In the end of 1980s, the FRF-based substructure synthesis method began to be studied. Jetmundsen et al.² set up the equations for classic substructure method. Van der Valk³ summed up the current difficulties of substructure method in testing part. And based on a benchmark model, a further study of the difficulties was made. Through an analytical model, Nicgorski and Avitabile⁴ discussed the problems with the system response prediction in implementation with actual test data. The numerical simulation results showed that the low-frequency information of a system is very sensitive to noise on the data. Nicgorski and Avitabile⁵ developed...