Fatigue life prediction method of cold extrusion reinforced hole structure

The invention relates to a fatigue life prediction method of a cold extrusion reinforced hole structure, which comprises the following steps: (1) carrying out a low-cycle fatigue test on a standard round bar sample to obtain low-cycle fatigue life data under a material working condition; (2) establishing a Smith-Watson-Topper (SWT) life model of the material based on the low-cycle fatigue test data of a standard smooth round bar sample of the material; (3) carrying out a low-cycle fatigue test on the unreinforced central circular hole flat plate sample under the working condition to obtain thelow-cycle fatigue life of the sample, and carrying out finite element simulation; (4) determining a critical distance expression by combination of the SWT life model and the fatigue life of the unreinforced central circular hole flat plate sample; and (5) establishing a Sines multi-axis fatigue criterion considering residual stress correction according to a plurality of stress-life (S-N) curves,and predicting the fatigue