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

• Published in: Theoretical and applied fracture mechanics 2018-12, Vol.98, p.30-37
• Main Authors: Mehdizadeh, Mohammad, Khonsari, M.M.
• Format: Article
• Language: English
• Subjects: Amplitudes; Austenitic stainless steels; Crack propagation; Entropy; Fatigue failure; Fatigue fracture entropy; Fatigue life; Fracture toughness; Friction; High cycle fatigue; Internal friction; Load; Low- and high-cycle fatigue; Mathematical models; Methodology; Nondestructive testing; Predictions; Thermography; Variable amplitude loading; Variable loading
• ISSN: 0167-8442; 1872-7638
• DOI: 10.1016/j.tafmec.2018.09.005

•Fatigue Fracture Entropy (FFE) successfully accounts for variable loading sequence.•Remaining useful life can be reliably predicted via FFE.•Experimental and FFE-based theoretical results apply to high- and low-cycle fatigue.•Variable loading and variable frequency experiments reveal efficacy of FFE-based predictions. 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.