Finite element modelling of a small-size motorcycle for frontal crashes

Different from passenger car safety, Powered Two-Wheeler (PTW) crashworthiness analysis is not systematic, and no legal requirements prescribe how to test full vehicle PTW safety. The only existing guidance is provided in ISO 13232; it prescribes computer modeling, but mainly for Multi-Body models and lacks some essential aspects for Finite Element (FE) models. The aim was to develop an FE model of a small (<150 cc) PTW for frontal crashes. In a reverse engineering process, a Yamaha YS-125 was disassembled and scanned to establish a basis for virtual modeling in LS-DYNA FE code. Analysis of physical crash tests guided which frontal structures were critical to replicate PTW dynamic responses and rider-to-PTW interactions. Two physical tests were conducted and replicated numerically: a frontal crash of the PTW into a rigid barrier and a frontal crash into the side of a Honda Accord, including the Autoliv-Humanetics PTW dummy as a rider. The scanned base model included five critical components in more detail: the front wheel, front suspension, headlamp, handlebar, and fuel tank. Precisely, tire pressure and rim failure mechanism were replicated; spring/damping characteristics of the suspensions and fork bending were adapted; handlebar and headlamp rotations were modeled; and fuel tank interaction with the pelvis was replicated. With these components correctly modeled and assessed, the developed PTW model is predictive of PTW and rider accelerations and motion during frontal crashes. These findings are a starting point for modeling safer motorcycles and defining regulations that standardize modeling techniques and validation of FE models.