Abstract
Bushings are structural elements which are used in automotive suspension systems. A bushing is an essential device to cushion the load transmitted from the wheel to the frame of the vehicle. It is an elastomeric hollow cylinder contained between an outer steel cylindrical sleeve and an inner steel cylindrical rod. The steel sleeve is connected to components of the suspension system and is used to transfer forces and moments from the wheel to the chassis. The elastomeric material reduces the shock and vibration in this connection. Dynamics simulation of the automotive suspension system involves the interaction between many components. The accurate determination of the transmitted forces and moments between components, the motion of the components, the stresses in the components, and energy dissipation is affected by the quality of the bushing model.
In this research, a bushing is regarded as nonlinear viscoelastic incompressible material and a specific modeling approach for torsional mode through the experiments was studied. A moment-rotational angle relation for a bushing is important for the simulations of multi-body dynamics. Hence, an explicit moment-rotational angle relation is introduced, which can be used in multi-body dynamics simulations. The relation between the moment applied to the shaft and its rotational angle exhibits features of viscoelasticity. For experimental research, ramp-to-constant rotational angle control test with MTS 858 equipment was used.
Pipkin-Rogers model, which is the direct relation of moment and rotational angle, was obtained and comparison studies between the experimental results and the Pipkin-Rogers results were carried out. It is shown that the predictions of the proposed Pipkin-Rogers model for the bushing are in very good agreement with the experimental results under the practical operation regions.
Keywords: nonlinear viscoelasticity, bushing, torsional mode, moment relaxation function, Pipkin-Rogers model