Stone Chipping, it is the mechanical damage caused to the vehicle by small flying stones, from the tyre. This damage to the vehicle affects aesthetics, accelerates corrosion, and reduces safety, making it vital for the manufacturer to provide stone chipping protection mechanisms. The aim is to avoid stone chipping related damage to the bodywork and assembly components in the early development phase. Therefore, it is necessary to predict the degree of damage to figure out the suitable measures against stone chipping, and numerical simulation provide a promising approach to model stone lofting.
The numerical multiphysics model proposed couples Discrete Element Method (DEM) for stones, Finite Element Method (FEM) for tyre deformation, Multi-body Dynamics (MBD) for suspension geometry.
Initially the proposed methods ability to predict contact patch is examined, which shows that vertical deformation and contact length strongly agree with literature. For the stone lofting prediction, the proposed numerical model is tested for multiple vehicle velocities of 30kmph, 50kmph and 80kmph for lofting angles and lofting distribution. The results show higher density of stones are lofted at lower angle and the density of stones decreases along the circumference of the tyre when measured from contact patch. It is also seen that tyre tread, stone shape and stone size has effect on lofting behavior.
Current methods of predicting stone lofting rely on experimental input through complex, expensive, and time-consuming lab tests along with visual observations. Statistical methods are also in use to predict stone lofting. Hence, a repeatable method that can model this complex behavior is proposed.
The proposed multiphysics approach has the capability to capture complex interactions like secondary collisions, the collisions that occur after lofting. Tyre-Stone pinching, the ability to capture the forces between the deformed tyre and the stones.