Shape Optimization Design of an Automotive Drive Shaft for Improving Fatigue Life

The drive shaft is one of the important power transfer components that transmit cyclic torsional loads produced by the transmission to the wheels. The drive shaft should be designed to meet the requirements of structural performance, such as static and fatigue strength, and a lightweight design by not only improvement of materials through the induction hardening process but also shape optimization, because of its frequent failure by the cyclic torsional loads from the transmission. In this study, drive-shaft shape optimization was carried out by using the design of experiment (DOE) and the Kriging model, in which nine shape design parameters were selected by a case study with consideration of the geometries of the components, such as BJ- and TJ-studs and tube; the orthogonal array was generated to reduce the time-consuming computational task for design-space exploration. The results obtained by the shape optimization showed that the maximum torsional stress of the optimized drive shaft decreased by 11.5% with a 3.7-fold increase in fatigue life, and the weight decreased by approximately 25%.