Investigation of plastic zone dimension in front of an external semi-elliptic crack on pipe of molecular bushing

Abstract

In automotive industry, molecular bushings transfer loads from steering gearbox to wheels on a vehicle. The pipe is one of the most vital member of these routing systems and manufactured using 41Cr4 sheet metal. For a pipe of molecular bushing, analytical solutions of crack tip plastic zone size is derived by using four yield criteria: Von Mises, Tresca, Hill48, and Hu2003. Hill48 and Hu2003 are useful criteria for materials with higher anisotropy such as sheet metals. Material’s hardening behaviour is modelled using bilinear isotropic hardening rule by coupling with associated flow rule under isotropic and large scale plasticity condition. The solutions are developed for mode-I loading case due to service conditions of the pipe. A finite element simulation is performed to collect stress intensity factors. Results are verified by comparing to those of Irwin and Dugdale. The plastic zone’s shape and size are analysed for different anisotropy cases. The results show that plastic zone have “kidney” or “butterfly” shapes depending on the yield criteria used. Increasing anisotropy has significant effect on plastic zone.