Multibody simulations of vibrations in a truck’s steering system

Sammanfattning: This thesis aims to explore if multibody simulations is a suitable method to investigate vibrations in the steering system of trucks. Vibrations in the steering system and subsequently in the steering wheel is a common issue that automotive manufacturers face. The vibration levels in the steering wheel are in some countries regulated and some vibration phenomena can even cause issues with the handling properties of the whole vehicle. Therefore being able to predict and reduce these with the help of multibody simulations would be of great value. The thesis does this by comparing the simulations to measurements. It investigates what parts can be approximated as rigid, what the effects different numerical solvers have and compares different driving scenarios. This can however be quite challenging, one reason being that the differential equations arising when performing multibody simulations of trucks are very stiff. The numerical challenges of this must be overcome while still keeping the resolution of the accelerations in the solution high enough to still be representative of reality. The thesis also explains how to mathematically model a physical system such that the numerical analysis of it can be efficient. The results show that the success of multibody simulations is very dependent on the test case. However, they also show that together with physical measurements multibody simulations can be a powerful complementary tool. The thesis also presents improvements that could be made to the model as well as certain key areas that need to be studied more in order to align the multibody simulations results with measurements. The multibody simulations software used to perform the calculations and the modelling in the report is Adams developed by Hexagon AB.