A Mitigation Strategy for Steering Wobble Phenomenon in Passenger Vehicle 2019-26-0183

Vehicles have a wide range of resonance band due to design nature & characteristics of its aggregates. First order, vehicle speed dependent, wheel disturbance due to wheel imbalances can result in excitation of different vehicle aggregates. Steering wobble refers specifically to first order road wheel excitation effects, in frequency range of 10-16 Hz, that manifest themselves as significant steering wheel torsional vibrations at highway speeds i.e. at the range of 80 km/h to 120 km/h on smooth roads. The tire, being an elastic body analogous to an array of radial springs, may exhibit variations in stiffness about its circumference; hence, it may vibrate at different frequencies due to wheel imbalance.

This paper introduces dynamic steering wobble analysis methodology either using vehicle speed at Discrete (individual speeds) or by Sweep (low to high speed) method to investigate steering wobble in the virtual environment using the full vehicle MBD model. It is also suggested prior to wobble analysis, vehicle level modal analysis should be executed to locate and separate different coupling modes & its shapes in working resonance bandwidth of system. The outcome of mitigation strategy is to model and optimize the significance parameter, which is contributing in the vehicle system, such as tire peak-to-peak unbalanced radial force, balance weight added to the tire and wheel system, Suspension, sub-frame, steering system modal frequencies, etc. Proposed mitigation strategy can help designer to accommodate early changes to meet best in class performance regards to steering wobble.