Experimental and numerical characterization of an epdm 55 grommet

This thesis work, carried out in collaboration with Pierburg Pump Technology S.p.a, aims to analyze and predict the behavior of a grommet made of EPDM 55 material. Such a component is part of the silent blocks mounted on pumps that the company produces for the automotive industry. The need for a tool to correctly predict the component behavior arose as a consequence of a few in-service failures attributable to thermal-mechanical damage. In some cases, the frequency-dependent component behavior caused the rubber element to burn out, compromising its vibration damping performance. To comprehend the grommet mechanical behavior and solve this problem, a large testing campaign was conducted directly on the component supplied by the company. It was subjected to displacement control conditions tests by applying a sinusoidal waveform whose parameters are the displacement amplitude and frequency set on an electro-dynamic machine. The data collected were employed to fit a predicting model for the hysteretic behavior, which is responsible for the heat build-up of the rubber leading to its thermal failure. The Bouc-Wen model was chosen for its capability to describe the non-linear behavior of materials subjected to cyclic loads. One of its standard versions has been modified to capture the viscoelastic grommet behavior. The analytical model, appropriately calibrated and validated, represents an important tool for the company to predict the grommet behavior under known loading conditions.