Identification of Crack-Tip Parameters Using Thermoelastic Isopachics and Differential Evolution

A curve-fitting routine based on a Differential Evolution (DE) is used to generate noise-free cardioid curves from thermoelastic data obtained from the neighbourhood of a crack-tip. The technique is benchmarked using simulated thermoelastic data. The generated ca rdioid curves are used to determine the stress intensity factors (SIFs) from slots and real cracks loaded in mode 1. The derived SIFs show excellent agreement with theory and confirms the va lidity of the approach. The curve-fitting approach allows more information to be obtained from the thermoelast ic data than previous analysis routines and will provide a basis for further development of thermoelastic stress analy is for application in crack-tip stress studies. A means for evaluating the far fie ld stress term, σ0x, from the generated contours is also described.