An implicit integration procedure for an elasto-viscoplastic model and its application to thermomechanical fatigue design of automotive parts

Thermomechanical fatigue (TMF) design has nowadays become essential for many industrial parts and cyclic elasto-viscoplastic constitutive models and their numerical integration are the crucial point of the problem. The paper first presents an implicit time integration scheme for an advanced constitutive model. This scheme is based on the return-mapping algorithm and proposes a use of the viscoplastic multiplier which enables to avoid Jacobian matrixes inversion and high computational cost. This peculiar numerical model is then integrated in a comprehensive computational TMF lifetime approach. The couple is shown to give the best agreement in terms of TMF lifetime estimation when compared with more simple TMF design approaches and an other constitutive model.