Vibration fatigue

Engineering

Materials science

Entropy (arrow of time)

Fatigue testing

Ultrasonic sensor

Vibration

Acoustics

Classical mechanics

Solid mechanics

Thermodynamics

Physics

Mathematics

Composite material

Structural engineering

Software engineering

Test data

Mechanics

International Journal of Solids and Structures

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.

Modeling ultrasonic vibration fatigue with unified mechanics theory