An analysis of thermal gradient impact in thermal-mechanical fatigue testing

Thermal-mechanical fatigue (TMF) testing is a good method to decrease the number of isothermal tests for non-isothermal behaviour laws identification. Based on experimental results of the TMF Standard European Working Group, this study aims to investigate the impact of thermal gradients on mechanical heterogeneity within the gage length specimen. The quality of the TMF test is examined by an energy criterion related to error bounds for nonlinear behaviour. A sensitivity analysis is then made for a given behaviour law identified on a TMF test to answer to the above question. Moreover the geometric instability phenomenon, already noticed by Sheffler and Coffin, is modelled herein.