Modeling ultrasonic vibration fatigue with unified mechanics theory

• Published in: International journal of solids and structures Vol. 236-237; p. 111313
• Main Authors: Lee, Hsiao Wei, Basaran, Cemal, Egner, Halina, Lipski, Adam, Piotrowski, Michał, Mroziński, Stanisław, Bin Jamal M, Noushad, Lakshmana Rao, Chebolu
• Format: Journal Article
• Language: English
• Published: New York Elsevier Ltd 01-02-2022; Elsevier BV
• Subjects: Curve fitting; Dynamics; Empirical analysis; Entropy; Fatigue failure; Fatigue life; Fatigue tests; High cycle fatigue; Mechanics; Mechanics (physics); Metal fatigue; Thermodynamics; Ultrasonic vibration; Ultrasonic vibration testing; Unified mechanics theory; Vibration tests; Metal fatigue; Thermodynamics; Entropy; Unified mechanics theory; Dynamics; Ultrasonic vibration testing
• ISSN: 0020-7683; 1879-2146
• DOI: 10.1016/j.ijsolstr.2021.111313

A series of ultrasonic vibration tests are performed on A656 grade steel samples, at a frequency of 20 kHz. A fatigue life model based on the unified mechanics theory is introduced to predict the very high cycle fatigue life of metals. Then, the fatigue life test data results are compared with the unified mechanics theory based model simulation results. It is shown that the physics-based unified mechanics theory can predict very high cycle fatigue life very well, without the need for the traditional empirical curve fitting a fatigue damage evolution function. The model does not require any curve fitting parameters obtained from fatigue test data. However, it does require deriving analytical thermodynamic fundamental equation of the material subjected to ultrasonic vibration fatigue. The thermodynamic fundamental equation of the material formulates the entropy generation mechanisms during the fatigue process. There are more than half a dozen entropy generation mechanisms during fatigue process. Entropy is an additive property, hence, the entropy generation due to all active mechanisms can be added.