Submarine pipeline steel hydrogen-induced fatigue crack propagation circulation cohesion model prediction method

The invention discloses a subsea pipeline steel hydrogen-induced fatigue crack propagation cyclic cohesion model prediction method, which adopts finite element model processing, and after cyclic stress is loaded on a finite element model, the processing process comprises the following steps: carrying out elastic-plastic analysis on a crack tip area in the finite element model of a test piece through a finite element analysis method; performing hydrogen diffusion analysis on the material; performing hydrogen-induced material performance degradation analysis on the material; performing cohesion analysis by using a cyclic cohesion model to obtain a damage index of a cohesion unit under the current time step, if the damage index is greater than 1, deleting the corresponding cohesion unit, enabling the crack to expand forwards and updating boundary conditions, and otherwise, entering a next time increment to return finite element analysis; and extracting the crack length and the cyclic stress cycle index under eac