Experimental and Numerical Analysis of an Off-road Vehicle Suspension

The suspension behavior affects significantly the performance of a vehicle. An optimal condition must guarantee the best compromise among conflicting performance indices pertaining to the vehicle suspension system, that is, comfort, road holding and working space. Therefore, in the development phase of a vehicle design a complete study should be done to verify the actual improvement of optimal suspension characteristics and adjustments in the vehicle overall performance. This work presents a dynamic analysis of an off-road conventional automotive suspension, which was developed for an off-road vehicle type Mini-Baja. A two-degree of freedom dynamic model was developed to study the behavior of the suspension and the influence of the main parameters in the transmissibility of accelerations to the passengers. The model considers the coupling between the front and rear suspension system. Numerical simulations were developed to study the behavior of the suspension submitted to a sequential disturbance, just as it happens when a vehicle in movement comes across a road obstacle like a hole or an elevation. The results obtained with this methodology were analyzed in agreement with the procedures and limits supplied by the ISO 2631-1/97 standard, Evaluation of Human Exposure to Whole-Body Vibration, regarding the aspects related to the passengers health and comfort. The model response was compared with experimental results obtained from accelerometers and load-cells in a simple test. The study developed indicates that this methodology can be used as an effective tool for the design and improvement of vehicle suspensions.