Fatigue limit evaluation of structure materials based on thermographic analysis

Abstract

The work presented here is dealing with implementation of new approach to fatigue limit determination. The approach is based on application of thermography on specimen that is step-by-step increasingly loaded. Detected temperature changes at different stress levels are evaluated and final fatigue limit level is determined.. Thermography analysis seems to have a great potential to reduce the material demand and to achieve the minimum testing time while the quality of test results remains comparable to standard approach. This is extremely useful in cases where the experimental material is strictly limited, such as new materials development, residual service life of in-service components determination or also, nowadays, for additive manufacturing components, where specimens preparation is expensive.Each specimen was tested at different stress amplitudes, where the test procedure consists of at least 8 loading steps. Results obtained with the thermography technique were compared with those obtained from standard high-cycle force-controlled fatigue tests under constant loading until failure in accordance with the ASTM E466-07 standard. All tests were done at room temperature with the cycle asymmetry coefficient R = -1.