Analysis and optimization for contact forces and transmission efficiency of an automotive ball joint

Contact forces and transmission efficiency of an automotive ball joint constitute important design goals of an automotive drive shaft system, which affect transmission performances of the ball joint and the drive shaft system. In order to analyze contact forces and transmission efficiency more comprehensively, a multi-body dynamic model for calculating contact forces and transmission efficiency of a ball joint is established. The effectiveness of the multi-body dynamic model is validated through experiments of contact forces and transmission efficiency of a ball joint. Based on the developed multi-body dynamic model, influences of the articulation angle, the ball number and the track offset on contact forces between the ball and the cage, and between the ball and the track are analyzed. To enhance the analysis and optimization efficiency of transmission efficiency, a proxy model for the transmission efficiency loss late is established on the basic of the multi-body dynamic model. Influences of the ball radius, the articulation angle, the friction coefficient, the central angle of the cross section of the cage rib, and the contact stiffness and the force exponent of contact pairs on the transmission efficiency loss late are analyzed. Using Sobol’ global sensitivity analysis method, the sensitivity of the proxy model is analyzed and influences of various factors on the transmission efficiency loss late are further determined. According to sensitivity analysis results, the articulation angle, the friction coefficient and the force exponent are selected as design parameters, and the transmission efficiency loss late is optimized through a numerical example.