Analysis On The Strength And Fatigue Life Of The W6Mo5Cr4V2 Steel Drive Shaft

Drive shaft is the key component for mechanical structure, its strength, fatigue life and reliability has a crucial influence on the mechanical structure's work performance and security. The fatigue life prediction and analysis of drive shaft can help make maintenance plans to prevent serious accidents due to fatigue fracture caused by drive shaft failure.The drive shaft of a heavy-duty vehicle must have high carrying capacity, quality alloy structural steel with medium carbon level always cannot meet requirements,so W6Mo5Cr4V2 steel was considered. The drive shaft bears some bending loads and high torsional loads, stress takes on multiaxial state. To ensure the reliability of the drive shaft, the research on the strength and fatigue under the multiaxial fatigue theory is presented in this paper.Three-dimensional finite element model of drive shaft was established with the software of ANSYS under proportional bending and torsional loading, and the elastic-plastic stress and strain of the drive shaft was analyzed.The laws of the stress and strain distribution of the drive shaft in different positions were studied, and the stress and strain results of the dangerous position were obtained. The fatigue life of the drive shaft was predicted with local stress-strain method, and the aerodynamic fatigue life was obtained.The multiaxial fatigue theory based on the critical plane theory is stated in detail and the critical plane of the drive shaft was determined. The multiaxial fatigue life model of drive shaft was established, and the multiaxial fatigue life of the drive shaft was predicted with the multiaxial fatigue theory combined with damage parameters of the critical plane and multiaxial fatigue parameters. To ensure the fatigue reliability of the drive shaft, The multiaxial fatigue reliability model was established, The multiaxial fatigue life of drive shaft under different degrees of reliability was achieved.W6Mo5Cr4V2 steel is high-steength steel, fatigue crack initation life is a main part of total fatigue life. According to the method of predicting multiaxial fatigue life based on critical plane, the sensitivity analysis method was used to analyze the relationships between fatigue crack initiation life and mechanical parameters of W6Mo5Cr4V2 steel. The results show that modulus of elasticity and yield strength are more sensitive parameters than others while poisson's ratio is less sensitive to fatigue crack initiation life. The results are in good agreement with statistical results of fatigue tests. Improving the anti-fatigue properties of W6Mo5Cr4V2 steel should be by improving the yield strength firstly.