Abstract
Keywords: Rough Road Simulation, Commercial Vehicle, Tyre Model, Multi Body System, Loadings
Whilst the MBS simulation of the longitudinal and lateral dynamics of vehicles has now reached an easily manageable level the description of high-frequency vibration excitation and its effect on comfort and strength is a greater challenge. In particular for the commercial vehicle sector there is a comprehensive field of activity in this respect. Here it is not only a matter of recording the different service conditions, which are completely different compared with those of a car, but also of taking into account the structuring of the vehicles based on a modular system and hence with a great diversity of variants. A major priority here is on the adequately precise presentation of the tyre-road contact, which forms the decisive excitation mechanism for the motion, forces and stress on the vehicle. This paper considers the process of the evaluation of two suitable tyre models from the comparison with cleat measurements through to the first simulation of the entire model on the virtual road. For the applications desired the FTire model has proved to be a good compromise of computing power, accuracy and parameterisation. Since no suitable testing facilities were available for the identification of the model parameters, in the course of the project a special cleat drum test bench was developed.
The initial point of this project was the evaluation of a semi-physical and a physical tyre model as to their suitability for rough road simulation. Simultaneously an extensive measurement programme was started for objective assessment. Due to the fact that hardly any test facilities for truck tyres exist, an existing roller test bed was adopted for cleat tests. The next step was a full vehicle simulation of a tractor with semitrailer on deterministic and stochastic roads. Verification of simulation and measurement was then repeated. One focus of this project was the sensitivity analysis of the tyre model to determine the influence of the different tyre parameters.
Rough road simulation is an established practice in the field of passenger car development. The complexity of trucks is much higher than that of passenger cars due to their higher kilometre performance, higher number of variants (number of axles, wheelbases etc.) and variations in parameters (e.g. payload). This results in a much higher demand for accuracy in the modelling of the tyre-road contact.