ABSTRACT
In engineering applications rubber materials are often subjected to a combination of complex dynamic loads. Hence, the viscoelastic behaviour of the materials under complex loading is important. Busfield et al. (1999), Busfield et al. (2000) and Davies et al. (1996) studied the dynamic behaviour of pre-strained strips of rubber subjected to a tensile oscillation. Suphadon et al. (2009) used a similar approach to study anisotropy in the viscoelastic behaviour. For a range of unfilled rubbers, at pre-extension ratios below 2 the loss modulus is independent of the pre-strain and the energy dissipation depends upon the change in geometry only. In this work larger prestrains to an extension ratio above 2 are observed using both unfilled and filled rubbers. The anisotropy in the loss modulus with strain can be examined by loading a pre-strained rubber sample with a superimposed torsion oscillation or a additional tension oscillation.
