Vehicle response to wind excitations

Abstract

Vehicle sensivity to transient cross-wind gusts has gained interest in the recent years. A vehicle's response to side-wind excitations can be determined either experimentally using a full-scale vehicle or model or mathematically using a simulation of transient cross-wind gusts and driver-vehicle model. This study presents a computer simulation of a driver-vehicle system's response to cross-wind excitations.

The two-dimensional wind fluctuations at two points on a moving vehicle in a turbulent wind field are derived from a Fourier time series representation of the power spectral density function obtained at a coordinate system moving perpendicular to the mean wind speed.

The dynamic model of a vehicle is represented with a form of nonlinear time domain equations of motion with four degrees-of-freedom model. The vehicle dynamic model contains a nonlinear tire model and lateral load transfer for tire forces. A modified two-level model is used for the driver to keep the vehicle in a straight line against cross-wind excitations.

After evaluation of the result of wind simulation at two points on a moving vehicle, two vehicles, a 1987 Ford Thunderbird and a 1987 Hyundai Excel, are tested with fixed steering and with driver control for different wind and vehicle speeds. The effects of the driver's parameters on a vehicle's response to cross-wind is investigated.