A theory for the isolation of the complex deformation characteristics of nonlinear viscoelastic materials

Abstract

This article reports on the development of a new numerical method for the separation of multiple interdependent nonlinear deformation phenomena. Whilst conceivably applicable to other classes on nonlinear materials, the method proposed was developed specifically for large strain nonlinear viscoelasticity. Characterized by a combination of elastic and viscous deformation contributions, the corresponding constitutive relationships become experimentally indeterminate when both components of response are nonlinearly interdependent. The theory presented here incorporates a methodology analogous to Closest Point Projection of computational plasticity which is used like a Newton type iterative solution for multiple, mutually dependent parameters. The proposed technique is shown to closely reproduce the results seen from numerical simulations given prescribed nonlinear elastic and viscous relationships. This is of particular benefit to the accurate determination of material model coefficients.