Multiaxial fatigue of the components is a very complex behavior. This analyzes the multiaxial fatigue failure mechanism, reviews and compares the advantages and disadvantages of the classic model. The fatigue failure mechanism and fatigue life under multiaxial loading are derived through theoretical analysis and formulas, and finally verified with the results of multiaxial fatigue tests. The model of multiaxial fatigue life for low-cycle fatigue life prediction model not only improves the prediction accuracy of the classic model, but also considers the effects of non-proportional additional hardening phenomena and fatigue failure modes. The model is proved to be effective in low-cycle fatigue life prediction under different loading paths and types for different materials. Compared with the other three classical models, the proposed model has higher life prediction accuracy and good engineering applicability.

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The small sample data under the highest stress level are augmented based on the improved Bootstrap method, and then the augmented data are converted to sample data under the lower stress levels with the Principle of Fatigue Life Probability Percentiles Consistency. Furthermore, the augmented sample data and the original data are fused into the equivalent large sample data to establish the P-S-N curve with higher accuracy. Meanwhile, a new method for calculating the fatigue damage parameter of the notched specimens is proposed based on the two-point method. A modified P-S-N curve is established to predict the fatigue life of other specimens with different stress concentration coefficients under different stress levels. In addition, the experimental data of three kinds of materials are collected to verify the feasibility and accuracy of the new method. The results show that the predicted fatigue life is in good agreement with the experimental life.