Reduced order models for dynamic behavior of elastomer damping devices

Abstract

In the context of passive damping, various mechanical systems from the space industry use elastomer components (shock absorbers, silent blocks, flexible joints,…). Among other specificities, elastomers have frequency dependent characteristics. The computational cost of the associated numerical models, using viscoelastic constitutive behavior, may become too expensive during a design process. To solve this problem, the aim of this work is to propose an efficient reduced viscoelastic model of rubber devices. The first step is to choose an accurate material model that represents the viscoelasticity. The second step is to reduce the rubber device finite element model to a super-element that keeps its frequency dependent properties. This reduced model is first built by taking into account the fact that the device's interfaces are much more rigid than the rubber core. Therefore, kinematic constraints enforce the rigid body motion of these interfaces, reducing them to twelve degrees of freedom only (three rotations and three translations per face). The super-element is then built by condensing the core of the finite element model on the interfaces via a Component Mode Synthesis (CMS) method, adapted here to viscoelastic damping. As an application, the dynamic behavior of a structure supported by four rubber devices under harmonic loads is analyzed to show the efficiency of the proposed approach.