Low and high cycle fatigue of automotive brake discs using coupled thermo-mechanical finite element analysis under thermal loading

To predict the thermal fatigue life and thermal stress phenomena of a brake disc, it is necessary to study the thermo-mechanical coupling effect in terms of braking conditions. Thermal fatigue stress of automotive brake discs was analyzed by using the coupled thermomechanical finite element (FE) simulation. The FE model was developed by considering the effect of conduction and convection heat transfer by frictional heat generation and film condition. Experimental boundary conditions of the brake dynamometer were applied to the simulation model. The structural stress due to the stress concentration effect on the bolt holes was also confirmed. The thermal fatigue life of the friction surface and the bolt holes was differently estimated depending on the influence of the stress amplitude. The strain-life relationship was used to predict thermal fatigue life in view of elastic and plastic deformation. The fatigue cycle ratio was also presented to calculate the fatigue life for different braking pressures.