Tyre Modelling for NVH Engineering in ADAMS

There is a growing need to use NVH analysis tools at all stages in the design process of a vehicle. The tyre is a key element for the assessment of the NVH performance of a vehicle. This paper presents how a detailed tyre model can be coupled to a vehicle model in ADAMS to simulate various NVH tests. Both standing and rolling tyres are investigated in the time and frequency domain. The detailed tyre model is first built using a non-linear FEA method. It is then sub-structured using the Craig-Bampton technique (fixed interface) to be translated into a flexible body in ADAMS. Different approaches are then used to simulate the tyre and suspension behaviour when rolling over obstacles or standing on a shaker. A tyre modelling for dynamic studies : What is it for ? MICHELIN has been developing for many years dynamic modelling of passenger car tyres dedicated to the comfort and noise performance. In this field, modelling links vehicle models and tyre models. It appears now clearly that the tyre is too complicated a structure to be considered as a simple spring for refined dynamic vehicle simulations. For example, some tuning between vehicle and tyre modes seems necessary to maximise ride comfort. Tyre materials taken into account Departing from the geometry description of the tyre, a 2D axisymmetric mesh is defined. It permits the calculation of the inflated state thanks to the knowledge of the geometry, the non-linear orthotropic materials laws and all the necessary extrinsic conditions (temperature, pressure, ...). At this stage, we generate a 3D mesh in order to apply load on the tyre. The deflected state is then obtained, from which the two dynamic reference states needed for the non-rolling and rolling models are derived. The resulting 3D tyre mesh commonly reaches 150000 dofs because for modal analysis it must be refined enough to catch correctly all the required modal wavelengths of the tyre. Modelling principles Dynamic substructuring methods are commonly used nowadays to describe the dynamic behaviour of components belonging to large structures. Application to tyre is Page 2 on 2 particularly well adapted, in spite of the presence of non-linear visco-elastic materials, because the tyre looks very simple from a geometrical point of view, the modal density is low at low frequencies and two interfaces only are present (tyre/hub and tyre/ground). Dynamic substructuring methods offer a way to build reduced models for any structure, based on the assumption that low frequency dynamic motions are dominated by low frequency eigenmodes.