A comprehensive study on the design & development methodology of automotive steel wheel rims undergoing highly transient cornering events

Wheel rim is one of the most critical safety parts in a vehicle. Cornering is one of the most important durability test requirements for a steel rim apart from others like vertical and impact loads. Based on the category of vehicle and customer usage pattern, the dynamic accelerated cornering test for testing wheel rims is derived. The simulation and certification of wheel for the required dynamic durability testing requirement involves many steps ranging from acceptance criteria derivation to reliably addressing known potential failure zones in steel rims. Given the pitch circle diameter, at the concept stage, the known effects of key parameters like crown height, Naïve radius are determined from DOE and used as reliable indicators on how the shape of the steel rim section should be. Potential failure zones are typically crown and naïve radius from weather side surface and vent hole from the inner surface. Key design elements like coining at vent holes and crown dimensions and their impact on stresses are also discussed. The accelerated cornering test done at a vehicle level is a highly dynamic test – which requires careful aggregation of damage history to address it. Deriving the acceptance criteria from mule vehicle is also discussed which requires step-by-step measurement including segregation of strain contributions of bolt torqueing, static wheel reaction, camber effects when vehicle is just grounded and its stabilization on rolling. Data is collected and postprocessed for the cornering test to arrive at robust acceptance criteria for the durability simulation. The reliability of the procedure is ensured by strain correlation between actual test and virtual simulation at the critical locations on the wheelrim. This activity for rims has enabled to derive key design guidelines for steel rim to ensure optimum performance within given weight constraints.