Determination and validation of viscoelastic material model for an epoxy compound in constrained layer damping applications

Mechanical vibration causes problems in many applications. Vibration damping of mechanical structures is of interest in relation to noise, vibration and strength of structures and it includes both internal material damping and the additional damping caused by the whole mechanical structure. High damping epoxies are visco-elastic vibration damping materials that were developed by VTT Technical Research Centre of Finland in cooperation with Noisetek. The most efficient way to prevent the harmful effects of vibration is to increase damping using constrained-layer systems that provide weight-efficient, high-level damping even for heavy machinery structures. Utilization of this adjustable epoxy based vibration damping material is based on accurate control of location of its glass transition temperature (Tg) region. In the middle of Tg the maximum mechanical damping is achieved the measured loss factor values for developed epoxies varies from 1.3 to 1.7. In practice, the properties of a given cured epoxy system are designed so that the maximum peak of damping is set to appear in the property window of predetermined thermal and mechanical vibration conditions. Temperature and frequency dependent material properties of high damping epoxies were measured (DMTA). Based on these measurements visco-elastic model for describing frequency temperature dependent properties is developed. Accurate material model enables to use of FE modeling tools to simulate efficiency of different damping treatments on vibration behaviour of real structures.