Material and Geometric Optimization of Cast Footrest Subjected to Shock Loads

The importance of style design has increased tremendously in Indian two-wheeler market and at the same time new styles become obsolete in a short period. This rapidly changing market trend demands simulation methodology to evaluate the component for various loads in the design stage itself to reduce the product development cycle time. Aluminum cast footrest is preferred for better looks compared to sheet metal or tubular footrest. Normal load carried by the footrest is quite low but consideration should be given for severe loads experienced by the footrest during adverse conditions, like for example, hitting against potholes at high speed. In this current work an initial design of a die-cast footrest bracket with a particular geometric configuration and material was analyzed using finite element analysis for static and dynamic loads. Since the muffler shares its mounting with the footrest, assembly level vibration analysis along with muffler was carried out to identify the critical regions from vibration point of view. Experimental strain measurements were done at the critical areas identified from the simulation for various road conditions. Initial design failed for shock loads at same locations as identified through simulation. Optimal selection of material was done based on strain rate on the component under various test conditions. Sensitivity of fillet radius at critical areas was studied through simulation for vibration and shock loads that resulted in an optimal geometry. The modified geometry with the optimal material selection passed severe load conditions like hitting pothole at high speed. Testing and simulation methodologies were developed to simulate several commonly encountered load conditions.