Nonlinear viscoelastic and viscoplastic constitutive equations with growing damage

Nonequilibrium thermodynamics, rate-process theory, viscoelastic fracture m echanics and various experimentally-motivated simplifications are used to d evelop constitutive equations that account for effects of viscoelasticity, viscoplasticity, growing damage and aging. Their form is more general than previously developed by the author, and allows for relatively general tenso rial effects of damage. Some important special cases are then covered, with emphasis on viscoelasticity. Evolution equations for the damage expressed in terms of internal state variables (ISVs) are discussed, comparing formul ations using scalar ISVs and tensor ISVs. Finally, some experimental suppor t for the theory is described. An Appendix illustrates the theory for an ag ing, linear viscoelastic material with growing cracks.