Suspension and chassis play a vital role in the structural performance of an off-road vehicle. The paper focuses on Computer Aided Engineering (CAE) modeling and simulation study of an All Terrain Vehicle (ATV) structure to analyze its static and dynamic behavior. An integrated MBD-FEA approach used for analysis purpose has been presented.
In the study, a Multi Body Dynamic (MBD) model of the ATV suspension system is built using ADAMS/Car. The effect of change in suspension hardpoints on suspension characteristics has been analyzed by carrying out Design of Experiment (DOE) study using ADAMS/Insight. This is done to minimize roll, camber and kingpin angle variation during vertical wheel travel, thus increasing stability of the vehicle under rough road conditions. This helps in optimizing the front and rear suspension geometry of ATV.
The Finite Element (FE) model of ATV chassis is prepared to check its structural integrity. The input loads at body attachment points for FE model are taken from MBD suspension bench test analysis. The input loads for impact analysis are calculated analytically. Since safety of driver depends on structural strength and robustness of chassis, it is important to evaluate the design for all possible load cases (viz., bench and impact loads). Necessary countermeasures are taken in the structure based on stress response.
Finally, various tests like double lane change, constant radius cornering and sine input are performed on full vehicle MBD model to predict its handling characteristics. This includes the steady state (understeer/oversteer behavior and roll angle) and transient (vehicle response-time lag) response. Various road profiles generated virtually in ADAMS/Car are further helpful in understanding the dynamic behavior.
The process methodology depicted in this paper is useful in design and development of ATV for SAE BAJA event. It provides an important feedback regarding vehicle structure during design phase itself well before actual prototype is built.