Assembly of a tire and a vehicle model to predict vibrations at the bushings
Examensarbete för masterexamen
Sound and vibration (MPSOV), MSc
This Master’s thesis targets the prediction of vibrations at the bushings of vehicle rear chassis due to an excitation at the tire patch for early analysis in the devel-opment stage at the Volvo Car Group. In the past a hybrid model has been used, which included a FEM model of a new vehicle design proposal and through mea-surements obtained spindle forces of an existing tire vehicle combination. However it is reasonable that these forces are di˙erent for a new tire vehicle coupling. In this thesis the measurement data is replaced by a modal tire model, which is provided by Continental AG, to become independent of testing existing vehicles. Recep-tance Coupling is used to assemble one tire to the vehicle in the frequency domain. Thereby the vibration levels at a chosen bushing are obtained due to an excitation at the tire patch for seven di˙erent harmonic excitation cases. In addition, a great focus is set on the sensitivity of the coupled solution to modal truncation errors in the tire model. Therefore an error metric is developed, which assesses the similar-ity between two FRFs using a floating bandwidth. As a result a minimum number of modes required for a desired frequency range and excitation case is given. In a second investigation uniform distributed random noise between ± 10 percent is added to the transfer functions of the tire and the vehicle model. The results show a deviation up to around 5 dB above the non-polluted case, for the major part of the frequency range, for some frequencies the coupled result show a greater sensitivity with deviation up to 20 dB for certain noise matrices.
Building Futures , Akustik , Building Futures , Acoustics