© 1993 by Oxford University Press
SHOCK FORMATION IN NEARLY ELASTIC MATERIALS
( Division of Applied Mathematics, Brown University Providence, Rhode Island 02912, USA )
One-dimensional wave propagation in nonlinear viscoelastic materials is discussed by using a nonlinear version of the compliance integral stress-strain relation of linear viscoelasticity theory. The analysis is phrased in terms of longitudinal waves in a stretched string in order to apply most directly to Kolsky's observation of tensile shock waves in stretched natural rubber. The compliance J(t) for a material that is nominally elastic can be approximated by power-law forms J(to)(t/to)2p with very small exponents 2p. By using approximations based on this fact, it is found that viscoelasticity theory gives results that are nearly the same as those that would be obtained from elasticity theory by treating J as constant along characteristies rather than as an absolute constant. Shocks appear as sudden but continuous changes. An initial-value problem with some relevance to Kolsky's experiment is discussed.