Kinematical and dynamic analysis of the suspension mechanism of a vehicle

The problem and the task formulation

When a suspension mechanism was developed, the client had to solve two tasks:

• To design the guiding device so as to ensure best option for building into the structure of elastic and shock-absorbing elements and the optimum vacillations of the machine frame.
• To select such elastic and shock-absorbing suspension elements that would provide for the best possible motion.

The client needed to calculate characteristics of the hydro-pneumatic spring plates so that to ensure convenient guiding of the suspension and giving comfort for the driver and a stable motion of the machine.

Problem-solving technique

To make all calculations for the suspension, it was enough for the client to hand over to us the suspension kinematical diagram and a tentative characterization of the vehicle. We obtained all other initial data by ourselves.

To select spring plates� parameters, we built a 3D dynamic model that represented the vehicle as a vacillating system. We used as input impact its motion along statistically averaged roads and field terrains. We also simulated the tractor behavior during basic agricultural and transport operations.

Following calculations and data analysis on vacillations of the main machine frame points and data on the supporting reactions in the machine wheels, we determined an optimum initial rigidity and an optimum spring plate-damping factor. The dynamic analysis results were used for stress/strain analysis by means of the FEA programs. All procedures were performed under CAD/CAE/PDM. 3D modeling was carried out with Unigraphics Software by EDS Company. Kinematical and Dynamic analysis was performed using ADAMS Software by MSC.

Results

Data of dynamic analysis of the damping system allowed us to adjust the suspension, combining compactness, efficacy and ease of maneuverability. The range of variation of traction force on the wheels of the machine was reduced by 40-68%, depending on the movement speed and road quality.

Our involvement in the project helped the client make in a brief period of time a reliable suspension with minimum dimensions and predetermined characteristics, avoiding re-design and expensive full-scale testing.