CHARACTERIZATION OF THERMO-MECHANICAL FATIGUE (FRACTURE, THERMAL STRESS, DAMAGE)

If an element that undergoes a temperature change is constrained in expansion, thermal stresses develop. In this study four different constraint levels are identified based on simple mechanics models. The constraint types are termed total, partial, over and notch constraint.; Thermo-mechanical fatigue lives for different specimen geometries, temperature ranges and constraint levels are determined. Stress versus mechanical, thermal and net strain loops are recorded and interpreted using a simple mechanics model.; The damage under thermo-mechanical fatigue is characterized based on the crack tip opening displacement range. This parameter could be used to predict the lifetime of complex members subjected to variable thermo-mechanical histories.