Abstract
This paper deals with influence of relative hole-layout to the initiation and propagation of the crack around the local hole in one-piece brake disc. Overload braking tests were carried out with two types of brake disc, which have same shape of hub part (decoration-windows), hole size and number of holes, but different hole-layout in circumferential direction. Thermal stress in hard braking was analyzed by FEM in which constraint temperature was applied on the elemental nodes observed in actual thermography test. Local compliance in circumferential direction around the hole was also evaluated at static state. The FEM results showed that local stress distribution around the hole was affected by the hole-layout. It suggested that the hole-layout changed the crack initiation process in the brake disc due to the compressive thermal stress, which induced tensile stress with plastic deformation as previous studies show. Different crack lengths were observed in two specimens having different hole-layout in the hard braking test. The crack length was related with the local circumferential compliance. This paper proposed that hole-layout should be determined as the local compliance in circumferential is high around the hole where elevated temperature is applied by the braking energy.
