Source Year: 1998

The non-linear stress-strain characteristics of filled rubber, and attempts at producing a non-linear model, have been reviewed. However, equivalent linear characterisation, yielding amplitude dependent values of shear modulus and loss tanget, is commonly used. Alternative methods of calculating the equivalent linear parameters: secant, harmonic, or skeleton methods, give different answers, as demonstrated for a particular rubber. The responses predicted from numerical integration of the equation of motion of an isolated mass using a proposed non-linear model are compared with those for equivalent linearisations of the non-linear model. The objective was to quantify the sensitivity of prediction of isolator performance to the choice of non-linear or linear modelling, and, in the latter case, linearisation method. For steady state responses to sinusoidal excitation, the equivalent linear model was found to be satisfactory, with harmonic linearisation as the preferred method. Differences are greater for transient responses, but, provided linearised parameters are chosen at appropriate strain levels, the differences are usually less than 20;.