Stiffness of simple bonded elastomer bushes. Part 1 – Initial behaviour

Abstract

This work examines the stiffness of cylindrical elastomer bush mountings in different modes of deformation. Stiffness predictions in different deformation modes obtained using published analytical relationships are compared with finite element analysis (FEA) and with experimental measurements made on a range of elastomer bush geometries. The results for the torsional and axial stiffness from all three methodologies agree reasonably well. However, existing analytical approaches predict values that are clearly incorrect for both the conical and the radial stiffness. Both a revised analytical and a graphical approach are proposed, which predict the radial stiffness more reliably. The work also demonstrates that to predict the initial stiffness of bushes manufactured from filled elastomers, a neo-Hookean stored energy function implemented in a FEA package is sufficient. Hence a single measure of shear modulus taken over the correct strain range is all that is required to characterise the elastomer behaviour for this purpose.