TEACHING TYRE TESTING AND MODELLING TO UNDERGRADUATE MECHANICAL ENGINEERING STUDENTS

Tyre characterization is an important step for full vehicle dynamic simulation: main tyre companies have their own testing machines based on rotating drums or flat beds, while special vehicles are used for tyre testing on real tracks with various road conditions (wet, dry, smooth, harsh…). The use of these experimental data, during a vehicle dynamics simulation performed with a multibody code, is allowed by means of several tools, such as data interpolation, physical or empirical tyre models. Many tyre models, with different degrees of complexity, have been proposed in literature: among them we can cite, because of their widespread use, Pacejka formulas. These well-known formulas present various degrees of load interaction capabilities that, generally, can be switched on/off in Multibody codes used for vehicle simulations. Usually, these programs come with a set of example files, based on these formulas, that describe tyres with various sizes (for cars ranging from city to sport) and that can be used at academic level to perform full vehicle simulations. To foresee the behaviour of such models is not easy and the simple calculation of formula outputs with plenty of graphs is not completely satisfactory; it is more intuitive discover the tyre characteristics using a testing procedure similar to the experimental setups. To this aim a virtual model of a testing machine with serial architecture has been built using MSC Adams. Users of this virtual testing environment, in our case undergraduate Mechanical Engineering students of a course on Vehicle Dynamics at Bergamo University, can obtain quite easily tyre characteristics, varying both test rig settings (camber, slip angle, vertical load and driving torque) as well as acting on tyre models parameters (for example scale factors of Pacejka formulas). Students can also appreciate the differences in tyre behaviour that arise when various load case combinations are activated.

Students, that already have some background in Multibody Dynamics, appreciated this approach and after a very short training on the lab they were able to proceed by themselves with a better understanding of tyre characteristics.