Shape Optimization of Drive Shaft for Passenger Vehicle in Terms of Lightweight Design and Fatigue Life Extension
A drive shaft of passenger vehicle has its own function such as transmitting the engine torque from the gearbox and differential gears to the wheels. It must also compensate for all variations in angle or length resulting from maneuvering and deflection for perfect synchronization between joints. Torsional fatigue failures are common at the connection parts of the spline in the end of the drive shaft when there is significant fatigue damage under repeated twisting loads. The automotive industriesare interested in research on lightweight design and fatigue life extension through shape optimization of drive shaft connections.In this study, the fatigue life of the drive shaft was evaluated by optimizing the shape of the drive shaft connections. 9 design variables were selected from the initial design shape of the drive shaftconnections, and the experimental points were created using the 3-level orthogonal array table by using the design of experiment (DOE) method. The shape optimization was performed by usingthe kriging method, in which results of structural analysis for the experimental points obtained from ANSYS Workbench was taken into account. The results showed that the maximum shear stress and the total weight decreased by 6.8% from 645MPa to 601MPa and by 25% from 3.5kgf to 2.6kgf, respectively. The fatigue life was estimated by a commercial software of n-Code Designlife. The fatigue life of the optimized drive shaft provided 2.2 million cycles, which is 3.7 times higher than that for the initial model.
Keywords - Drive shaft, Fatigue life estimation, Passenger vehicle, Shape optimization, Torsional fatigue failure.