A Motorbike Multibody Model for the Front Suspension Offset Analysis

The main aim of the study is to model a system capable of analysing driving differences as construction parameters of an off-road motorcycle change: the forces that reach the rider while overcoming obstacles will be observed. For this purpose, we created a multibody model that allows to carry out simulations and thus observe the behavior of the motorcycle in various configurations. Particular attention will be paid to the front part of the vehicle, namely the steering head, triple clamps, and telescopic forks. Then, at the end of the analysis, some considerations will be made on the geometric parameters and the consequent behavior of the vehicle. The model used in the tests was entirely created from scratch in the Matlab-Simulink environment. This program was chosen because it allows a wide variety of simulations and projects due to its extensive library of blocks and functions. Additionally, its use was further facilitated by the full license provided by the Politecnico di Torino and the numerous add-ons useful for various purposes. Some parts of the model were created in collaboration with the 2WheelsPolito student team, which allowed me to use informations that would otherwise have been difficult to obtain without their track tests. Thanks to their road tests, it was possible to use tire related parameters that made the analyses more precise and in-depth. Their experience also allowed the model to be created as efficiently and simply as possible. The results of the work could show how certain geometric choices lead to greater comfort or drivability, thus being useful for the development of new models of triple clamps, forks, or motorcycles as a whole. A new model created from scratch could show behaviors differently, revealing previously unobserved results. It could also introduce a new way of generating a simulation, perhaps faster or more detailed. The entire work of designing, testing, and refining the model has the ultimate goal of collecting data and conducting some analyses related to the front suspension of the motorcycle. In particular, we will focus on the triple clamps offset and on the wheel pin offset. These two variables play a key role in defining the motorcycle’s trail and, consequently, influence the forces and torques transmitted to the rider when the wheel is subjected to the terrain. The final goal is, through the analysis of the simulations, to understand in which situations it is more advantageous to create the trail with the triple clamps and in which with the pin, assuming there is a difference.