Determining Optimal Suspension & Body in White Mountings to maximize Off-Road Capability of Passenger Vehicles

<div class="section abstract"><div class="htmlview paragraph">The automotive market trend is shifting more and more to SUVs and crossovers. This, therefore, means increasing consumer demand for off-road abilities in passenger vehicles. While dedicated off-road platforms provide a path to performance robustness, getting the same level of functionality out of a passenger vehicle with minimal architectural changes proves to be a great feat for engineers. One highly critical performance determinant in the domain of off-road ability is wheel articulation, it requires independent movement capacity of the wheels to keep contact and stability over uneven terrain. Traditional articulations found in passenger car suspensions—created for comfort, packaging, and on-road dynamics—are limited by suspension geometry, damper alignment as well as compliance setup.</div><div class="htmlview paragraph">Damper side loads- were not considered a significant factor in suspension systems that are operating within their original intended design envelope for on-road use. However, when the vehicle is taken off-road, extreme conditions lead to lateral forces during an unseated exaggerated wheel travel, these can result in seal degradation as well as rod bending increasing friction (stiction) leading ultimately to damper failure. Seal durability and general component integrity are not the only issues increased side loading will decrease articulation reduce traction and degrade ride quality during severe terrain inputs. Articulation- is essentially a measure of flexibility in the suspension which directly controls off-road performance characteristics. With limited articulation there is wheel lift traction loss and increased chassis contact. A major limitation to achieving full articulation is damper side load-the perpendicular force to the damper shaft created from angular misalignment in suspension travel. This also increases the compressive stress on the damper rod. Therefore, an optimization of the rod diameter, length, and material is required. The Ramp Travel Index (RTI) is a means of expressing articulation by using the measure of ramp height that can be attained by a vehicle climbing with one wheel while maintaining contact with others. A high RTI indicates good off-road capability. There exists an interrelationship between suspension geometry, damper side load characteristics, and axle alignment in determining off-road performance; this paper proposes an optimization guideline to overall improve wheel articulation specifically for passenger vehicles through these parameters: wheel travel, suspension hard points, and damper mounting orientations.</div></div>