Multi-Body modelling and mechanical analysis of a steering system adopted on a light-duty commercial vehicle

A work like this wants to define a procedure that can be taken as standard when developing a model that wants to simulate how a vehicle works in terms of driving dynamics. The first focus is on the modelling side of the work, modelling took the majority of time in this work, this is mainly due to the fact that a new software had to be learned to fully develop a reliable model. Every steering system is different, from this premise it is almost impossible to create a standard guide and procedure valid for every study case. Some components are common among Adams Car models, this made possible to define at least how some components are commonly created. Additionally, two appendices were added to this work, these two brief documents define the procedure to get two of the most important model elements that were needed by this thesis. Concerning the work done on simulations, the main objective was to check that each model used in the software gave reliable results. The modelling work was focused on the steering part of the vehicle, for this reason the first simulation study was only on the steering system, the steering assembly was evaluated when steering motions were performed. From this it was possible to pass the study to the front suspension, when doing a steering test, the suspension will be involved in some way. To check that the steering system did not cause a conflict with the way the suspension worked, parallel and opposite wheel travel tests were performed, giving a good idea on the suspension travel, tests were made to understand the behaviour of the system under these conditions and to check that the behaviour of the system was realistic. The tests that gave the best review in terms of vehicle performance are the ones made on the complete vehicle, each test has a different objective, the ramp steering test has the role of defining the limit of grip of the vehicle and the forces and acceleration that are subjected to the vehicle components. The step steer has the objective to understand how well the vehicle reacts to a sudden manoeuvre and its ability to stabilize itself. At last, the sweep steer test evaluates the frequency response of the system, these three tests were carried out to validate the models created when applied to the full vehicle model. This work wants to underline the procedure followed to fully define and compare dynamic behaviour, from the basis of this thesis more accurate models could be used to deliver even more accurate results. A study like this is also capable of being versatile to different configurations, this is especially useful when talking about commercial vehicles, which are often created in a myriad of different configurations, the results presented in this thesis are introduced to define which are the most important parameters that can be used in evaluating the vehicle dynamic performance, by following the steps of this work it is possible to have a procedure to define and compare different vehicles.