Design optimization of armored wheeled vehicle suspension lower control arm

Abstract

In this study, design optimization of the lower control arm, one of the main parts of double wishbone system widely used in the armored wheeled vehicles, is performed. The crucial factor in design is to keep the vehicle weight at a minimum especially for the amphibious vehicles that can operate in both the land and water. In this study, after the validation of the finite element (FE) analysis of suspension lower control arm with on-vehicle tests, weight optimization study is performed by using surrogate models. In FE model validation, strain values are collected with strain-gauge from the lower control arm of the 8 x 8 wheeled vehicle and the similar boundary conditions are applied to the FE model. A surrogate based approach is used in optimization. The training points for surrogate models are generated by using central composite design. Genetic aggregation surrogate modelling technique available in ANSYS Workbench. It is found that the weight of the control arm can be reduced from 25.2 to 21.8 kg, indicating a weight reduction of 13.3%. This leads to approximately 27 kg weight reduction in total for 8 x 8 vehicle. Finally, the performance of the optimized design is evaluated under two off-design quasi-static load scenarios (pothole strike and pavement crushing) that may be exposed on the suspension while the vehicle is in motion and preferred by vehicle manufacturers. It is observed that obtained stress values are below the yield strength of the material, and the off design performance of the control arm is verified with the safety factor of 1.46 for pothole strike scenario, and 1.08 for pavement crushing.