Lifetime prediction of structures in anisothermal viscoplasticity coupled to damage

Abstract

The anisothermal conditions are introduced in the constitutive equations of elastoviscoplasticity through the state kinetic coupling theory. This allows us to consider elasticity, isotropic and kinematic hardenings and damage as coupled phenomena that can be used to predict the crack initiation on structures by finite-element calculations. The identification of material parameters is performed in the range of temperature 20–650°C for the nickel-based alloy Inconel 718. Several levels of couplings in the structural calculations may be performed: uncoupled, locally coupled, and fully coupled. Two applications are given: the first one is devoted to the damage analysis of a hollow sphere by the fully coupled method whereas the second simulates the crack initiation in a notched plate subjected to a cyclic thermomechanical loading by the uncoupled approach.