Validation of 2D Mathematical Model Applied to Reach The Zero Bump Steer

Walace T. Chicuta

doi:10.4271/2014-36-0360

Front bump steer is the steering movement of the front wheels as a result of vertical travel without input from the steering wheel. A requirement for automotive front suspension usually is defined as “as little bump steer as possible” in order to avoid unpredictable vehicle behavior on rough surfaces and also to increase the lifespan of the tire.

The aim of this study is support this development without the usage of kinematics software or at least reduce the time spent in the software, since many people does not have access to this engineering tool. Therefore a mathematical model based on 2D kinematics model was developed with the purpose to determine the location of the tie rod inner hardpoint, once that the main suspension geometry parameters was defined (caster, camber, scrub radios, caster offset and Ackerman angle).

The mathematical model validation was made in the OptimumKinematics software, where several analyses were run, each with different suspension setups, with the aim of evaluate in which conditions the model can be applicable.

This study also seeks to obtain the validation of the 2D model introduced on “The Automotive Chassis: Engineering Principles” [1] where this method is described.

The analyses exhibit similar values between the results obtained on it and the results shown in the mathematical model, validating the proposed model, considering its limitations.

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Validation of 2D Mathematical Model Applied to Reach The Zero Bump Steer 2014-36-0360

SAE MOBILUS