Component structural equivalent research based on different failure strength criterions and the theory of critical distance

• Application of the theory of critical distance (TCD) in the crankshaft.
• Combination of TCD and failure model determination and different stress distribution.
• Experimental verification for the prediction result.

Fatigue limit load is one of the most important and concerned factors in designing and manufacturing critical mechanical parts such as the crankshafts. Usually, this governing parameter is obtained by experiment, which is expensive, time-consuming and only feasible in analyzing the case of simple structure. Still, there's a big obstacle to clear to get the fatigue limit load of a sophisticated structure effectively and efficiently. Based on the theory of multi-axial fatigue and critical distance, this paper first analyzes the stress state of the crankshaft under a bending moment by a coordinate transform method. Then, suitable fatigue criterions and stress distribution are chosen to determine the fatigue limit value. Also, the experiment is conducted to verify the prediction result. As the simulation results through the critical line method show a better consistency with the experiment data, the effectiveness of the critical line method make it more recommendable to be put into engineering practice than the critical point method in predicting the fatigue limit. The conclusion in this paper may enlighten the understanding of the fracture behavior of a complex structure and provide a valuable reference for fatigue limit prediction in engineering application.

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