MODELLING AND ANALYSIS OF AN ELASTOMER DAMPER

Abstract

A new rheological model is proposed to predict the behaviour of a magnetorheological elastomer (MRE) material. The proposed model is consists of three parameter linear solid model, a stiffness element and a damping element to predict the viscoelastic properties of the rubber matrix, field induced properties of the composite and friction between elastomer and iron particles respectively. The proposed model validated by comparing the result of model values for stress and strain with the experimental values extracted from a published article. The storage modulus and loss modulus of the MRE composite is derived from the proposed model. This report also proposed the development of three different adaptive tuned vibration absorbers (ATVAs) based on magnetorheological elastomer (MRE) to reduce the torsional vibration of powertrain during acceleration whose dynamics is represented by three different torsional vibration models. An effective functions for the storage modulus, loss modulus and loss factor as a function of the applied magnetic field strength are developed to aid the ATVA design. The ATVA characteristics i.e., stiffness and damping coefficients, required for numerical simulations were evaluated from the developed formulae. By tuning the ATVAs natural frequency and fixing the ATVAs at right position, natural frequencies of the powertrain can be thrown away from the resonance area. The vibration response of the powertrain models with and without ATVAs is numerically evaluated and compared to check the ATVAs effectiveness. By using the ATVAs, the powertrain frequencies successfully thrown outside the resonance area and vibration response of the powertrain system reduced significantly. During the aircraft movement in landing, taxing and takeoff, due to dynamics of tire and landing gear, an oscillatory phenomenon evolves which is known as shimmy. At present most of the aircraft use hydraulic damper in the landing gear to control the shimmy. In this report an effectiveness of the MR damper for the control of shimmy in nose landing gear of aircraft is studied and compared with hydraulic damper. For the numerical simulation, torsional and lateral bending interaction in landing gear is considered. First vibration response due to shimmy phenomena, without damper is evaluated. Then the vibration response due to shimmy phenomena with hydraulic damper and MR damper evaluated separately and compared. It was found that, the MR damper has better shimmy suppression capability than the hydraulic damper.