Coupling Between 1D-3D Simulation Results to Predict Cavitation in Motorcycle Forks

Fork system is a primary component for motorcycles because it assures the contact between tires and road, therefore the safety and the driving feeling. Usually fork optimization and tuning are experimentally made involving the generation of a high large number of prototypes and an expensive experimental campaign. To reduce the design and the tuning phases of a generic damper system, the numerical simulation should be considered. In this paper, a one-dimensional (1D) model of fore-carriage forks for road applications is presented. The model was built-up in AMESim code. In particular, the authors’ attention was focused on the detection and analysis of cavitation phenomenon inside the fork. As well known, the cavitation is a complex three-dimensional (3D) phenomenon that implies the phase transition. Cavitation development and prediction are beyond 1D model capabilities, therefore the 1D fork model was improved by 3D Computational Fluid Dynamic (CFD) multiphase simulations performed by using Fluent v12 (beta version). 3D numerical results were integrated into the 1D model to define a new numerical test methodology able to reproduce the overall fork behaviour. All 1D numerical results were compared to experimental damping force traces obtained for different fork rod axial velocities.