Thermomechanical Fatigue: Testing Methods and Application

The fatigue testing performed at constant temperature, are unable to fulfill the requirements to reproduce the anisothermal solicitation mechanisms. Therefore, new testing techniques, such as Thermal Fatigue (TF) and Thermo Mechanical Fatigue (TMF), were developed. Although very complex and expensive, for some working situation anisothermal fatigue testing reproduces much more realistic conditions than isothermal fatigue testing. TMF testing is characterized by the superposition, independent and simultaneous, of strain cycles to temperature cycles, both time dependent. This work presents the development of the TMF methodology currently in use at LAPROMEC, EESC-USP. To illustrate the effectiveness of the installed testing system, two characteristic cycles were imposed during testing: in-phase and out-phase cycles. The results are present in this work.