Optimization of reinforcement turn-up effect on tyre durability and operating characteristics for racing tyre design

The damage occurring around the tyre bead region has been pointed out as one of the causes of critical failure during the service life of a tyre. This study investigates the influence of the carcass (body) ply turn-up and bead reinforcement turn-up around the bead region on tyre durability and operating characteristics using finite element analysis (FEA). A slick motorsport tyre with two carcass plies was modelled in ABAQUS based on the material properties obtained from tests and the profile provided by the tyre manufacturer. Various factors including the material property, the cross-section area, the spacing and angles of the reinforcement cords and the height of reinforcement turn-up, were characterized by numerical experiments using the design of experiment (DOE) method. The effects of these parameters on tyre durability and operating characteristics, in terms of mean response analysis of carcass stress, vertical stiffness, lateral stiffness, cornering stiffness and the strain energy density (SED) of elements in the critical region, were determined from the finite element tyre model. Similarly, optimum reinforcement turn-up heights were obtained and provided predictive information for tyre design purpose. Furthermore it was observed, from both experiment and prediction, that the vertical stiffness was rather high for the requirement of the Formula Student (FS) racing car. In order to reduce the tyre vertical stiffness and improve the tyre durability, an improved tyre based on the original design but with single carcass ply was proposed. The FEA results on tyre durability and operating characteristics from both the original and improved design tyres were compared. The FEA predictions indicated that the improved design model was capable of providing the required tyre characteristics as well as improved tyre durability. It is therefore proposed that the predictive technology using FEA can be utilized to optimize the tyre reinforcement turn-up effect in future tyre design.