Thermomechanical fatigue, or TMF testing adds the sophistication of performing realistic thermal cycling with mechanical fatigue testing to simulate real-world service conditions of materials and engineered components. Thermomechanical fatigue tests characterize materials response to cyclic mechanical loading with fluctuating temperature, common to high-temperature alloys used in jet engines and heat exchangers, using combined in-phase and out-of-phase mechanical and thermal cycling. TMF compatible test equipment includes special application software that can read temperature and total strain measured by an extensometer and calculate and control mechanical strain in real-time.
ASTM E2368 covers thermomechanical fatigue (TMF) properties of metals under uniaxially loaded strain-controlled conditions. Within ASTM E2368, a fatigue cycle is considered as a condition where uniform temperature and strain fields over the specimen gage section are simultaneously varied and independently controlled. ASTM E2368 TMF tests are performed in support of such activities as materials research and development, mechanical design, process and quality control, product performance, and failure analysis.