Influence of Shock Absorber Non-Linearities Over the Vehicle Dynamics Behaviour 2014-36-0018

Automotive industry has shown, in the recent years, a dramatically increase of competition at emergent markets. The incoming of new Brands, for example in the Brazilian market, is causing the OEMs to decrease costs while increase quality, which represents a big challenge nowadays.

In this challenging scenario, virtual simulation has become mandatory. While cutting costs since no physical prototypes are required, virtual models also reduces development time. Time to time, as computers processing capacity grows, virtual models are becoming more and more accurate, being able to capture even high non-linear phenomena, which ten years ago would not be feasible.

It is also known the natural tendency of vehicle dynamics engineers to develop shock absorber tuning only by means of subjective evaluation. Many reasons can be raised to this tendency, but one of them is the lack of representation of the entire shock absorber behavior in the virtual models. In this sense, the present work shows an attempt to capture the main non-linearities of shock absorbers that affect the most the vehicle behavior in terms of ride and handling. Two main effects are pointed out: shock absorber displacement dependency, especially for small and large wheel travels and time lag of response. A vehicle dynamics model was created using a functional model and validated against measured data. As functional simulation mode does not solve the multi-body equations for each integration step, it is still feasible to compute components non-linear behavior within the vehicle dynamics model without demanding too much simulation time. The addition of such phenomena in the damper model showed a better accuracy for the vehicle virtual model making it a better tool for development purposes for vehicle dynamics engineers. In this way, by enhancing the shock absorber model one aims the vehicle numerical model to help in the damper tuning process, reducing development time and improving efficiency in the car line vehicle project.