Responses of Model Viscoelastic Materials to Impact

Abstract

As part of a continuing exploration of the mechanical behavior of materials which have temperature-dependent properties, the effect of a hammer blow on a small sample of model viscoelastic material is considered. In this situation, the duration of the experiment is long compared with the time required for stress equilibrium to develop and short in comparison with the thermal relaxation time of the sample. The analysis shows how a material which responds in an almost perfectly elastic manner to a light blow can respond in a viscous manner to a heavy blow. It also suggests that a homogeneous continuum with properties that would make it acceptable as a structural material must be brittle. This result may contribute to the understanding of the important relationship between microstructure and ductility. The hammer experiment involves relatively high strain rates which vary continuously during the deformation. In earlier work, the constant deformation rate case was studied. The latter situation is difficult to produce in the laboratory in the range of rates of interest here and is less likely to arise in practice.