1992-02-01

Development and Validation of Light Vehicle Dynamics Simulation (LVDS) 920056

This paper describes the development and validation of an advanced microcomputer based simulation developed to investigate the complex dynamic responses of light vehicles in a variety of maneuvers. These maneuvers include cornering with braking or acceleration as well as vehicle skidding, spinning, and rolling over.
A three-dimensional, non-linear vehicle dynamic model having eight degrees-of-freedom is generated according to user specifications. Multiple masses are connected through suspension elements to properly account for vehicle forward, lateral, vertical, roll, pitch, and yaw directional dynamics. To build an accurate model, any one of 8 different commonly used front suspension systems can be employed in conjunction with any one of 19 different rear independent, semi-independent, and dependent suspension systems. The capability of implementing various suspension systems allows the utilization of important kinematic and dynamic effects of these suspensions on vehicle response. The tire model utilized is based on the non-dimensional slip angle approach and is capable of working over a wide range of normal to extreme operating conditions. These conditions include normal loads of up to 400% of standard load, slip angles from -90 to 90 degrees, slip ratios from -1 to 1, camber angles to 60 degrees, and an unlimited friction regime. The tire forces and moments generated are non-linear functions of actual normal load, longitudinal slip, slip angle, camber angle, and tire-roadway frictional characteristics. The tire model predicts wheel locking, spinning and/or saturation, and automatically simulates the changes in tire behavior caused by these conditions.
The results presented in this paper demonstrate that the Light Vehicle Dynamics Simulation (LVDS) is capable of accurately predicting a wide spectrum of light vehicle maneuvers ranging from low “g” cornering to severe spin out and rollover. The LVDS simulation was successfully validated using experimental results obtained from several vehicles (cars, utility vehicles, vans, and pickup trucks) in a variety of handling and rollover maneuvers and in both unloaded and loaded conditions. It has proven to be a reliable tool for the investigation of the dynamic behavior of light vehicles.

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