Increasing compressor wheel fatigue life through residual stress generation

Abstract

Cast aluminium compressor wheels in turbochargers may fail following cyclic loading in service due to crack growth from the highly stressed bore of the wheel. In this paper it is proposed to subject wheels to a single over-speed event to generate beneficial, compressive residual stresses at the bore of the wheel and hence reduce stresses at the working speeds. A theoretical model has been identified to simulate this process and a technique developed to determine the model input parameters. This closed form analytical model shows good correlation with a detailed finite element analysis over a wide range of over-speed events.