With advancements in powertrain technologies & light weighting of vehicle structures, the average driving speeds of motorcycles are increasing. This makes it important to safeguard the vehicle structure from possible impact loads or crash events. The front suspension of a motorcycle typically consists of telescopic front fork which acts as a structural member as well. Thus modern vehicle front forks should be designed keeping in mind frontal impacts as well. Which means the structural stiffness of front fork needs to be optimally designed so that during impacts, the structure should deflect absorbing the bulk of the impact energy safeguarding the rest of the vehicle structure including chassis. At the same time the front fork should not break.
The popular design improvement techniques like increasing section modulus, heat treatments to increase strength may or may not have positive effect on impact strength. Even some of the finite element analysis techniques like linear and/or static analysis would not be able to simulate the impact dynamics. The impact testing would not be always feasible during new product development.
This paper focusses on a virtual simulation methodology for predicting the behavior of front fork under impact loads. Various design aspects, critical to impact performance are identified. An exhaustive impact testing is done for multiple design configurations. It is well known that the failure mechanism under impact events is different from the conventional failure modes & the impact simulation methodology successfully captures it well. Further based on the simulation, design philosophy & guidelines are arrived at to ensure design adequacy under impact loads.