On the Performance of Silicon and Polyurethane Rubbers in Structural Vibration Damping

Rubbers are often utilized as viscoelastic materials in passive to control the vibration of structure passively. These damping materials are typically used in sandwich or multi-layered structural configurations as constrained layers. The present work is carried out in this context, where the usefulness of two commercially available rubbers, namely silicon rubber and polyurethane rubber, is investigated for passive constrained layer damping (PCLD) of beams in the sandwich structural configuration. With the CLD treatment, this sandwich structural form may be either asymmetric or symmetric. The symmetric configuration uses the same thickness for the layer between the face and substrate, but asymmetric designs assume different thicknesses. In our present study, the analysis of asymmetric sandwich beam configuration has been selected. First, the frequency-dependent storage and loss moduli of the silicon and polyurethane rubbers are estimated experimentally through a frequency sweep test in Dynamic Mechanical Analysis (DMA) machine. The experimental data is subsequently used to obtain the functional variations of the moduli with the frequency which is based on the fractionally derived viscoelastic constitutive model. Based on these frequency-dependent properties of the rubbers, a 3D Finite Element Analysis (FEA) modeling of the whole structural beam is illustrated to analyze the damping passively in the overall structure by means of evaluating free and forced vibration responses in the desired frequency range. Both the rubbers show promising damping in the constrained layer damping (CLD) configuration. However, polyurethane rubber provides more damping in the CLD treatment than that using silicon rubber. The effect of some system factors, like the rigidity and the thickness of the damping (viscoelastic) layer on the silicon/polyurethane-based CLD configuration, is also illustrated.