On the application of fracture fatigue entropy to variable frequency and loading amplitude

A nondestructive fatigue model is developed that utilizes the thermographic methodology and the concept of entropy production to predict the residual life of a component subjected to variable amplitude loading. The applicability of the model is investigated using a set of experiments on stainless steel 304 covering both low- and high-cycle fatigue regimes. Results are also presented that compare the predictions of the residual life with those obtained by applying the Miner's rule, quantitative thermographic methodology, fatigue driving stress, and the fatigue driving energy approaches. The results show that the maximum and average errors of the present approach are much lower than the above-mentioned methods. Also presented are the results of a series of variable-frequency fatigue experiments that are successfully predicted by the present methodology.