Fatigue resistance of brake system components made of aluminium alloy

In this paper the influence of the microstructure, in terms of the DAS index, and of the geometrical notches on the fatigue resistance of a brake system component, made of aluminium alloy, was investigated. G-AlSi7Mg die casting automotive brake calipers were considered in this study and different die casting processes for their production were analyzed. Several experimental fatigue tests on rotating bending specimens were carried out in order to directly correlate the fatigue behaviour and the material microstructure. The effect of the geometry was analyzed by means of pulsating pressure tests on the full scale components, with and without considering the braking torque. Accurate three dimensional FE models of the half brake caliper subject to the highest levels of load were also developed. Different theoretical models, such as the Heywood equation and the Sines criterion, were applied to predict the fatigue life of both the specimens and the component.