An improved method for fatigue life prediction of metal materials based on thermodynamic entropy

•The functional relationship between fatigue fracture entropy and loading amplitude is clarified.•Analyzing the normalized fatigue cumulative entropy and cycle correlation properties.•The entropy generation rate is proportional to the loading amplitude.•The cumulative entropy is inversely proportional to the loading amplitude. To determine the relationship between thermodynamic entropy generation rate and cumulative entropy and fatigue performance of metal components during fatigue. The surface temperatures of the specimens under different loading amplitudes and frequencies were recorded by infrared thermography. The effect of internal friction is not considered. Then the entropy generation rate and cumulative entropy are calculated, and the relationship between fatigue life and entropy is constructed. The calculation results show that under the same loading frequency, the entropy generation rate is proportional to the loading amplitude, the fatigue cycle is relatively low, and the cumulative entropy is inversely proportional to the loading amplitude. The cumulative entropy is only related to the loading amplitude, but not the loading frequency. A fatigue life prediction model based on the thermodynamic entropy of metals is established, which can be used for the real-time assessment of fatigue damage of metal components.