Experimental Analysis for Determination of Longitudinal Friction Coefficient Function in Braking Tractor Semi-trailer

The longitudinal friction coefficient is a very important parameter to calculate vehicle dynamics. The theoretically longitudinal friction coefficient is often used to investigate the vehicle dynamics. However, the longitudinal friction coefficient depends on many factors and changes when the vehicle moves on the actual road. This paper presents the experimental method to determine the longitudinal friction coefficient function when braking the tractor semi-trailer on the road. The results of this study can be used as an input to dynamic survey model for the tractor semi-trailer and to verify the theoretical model. The experimental results showed that when braking the tractor semi-trailer on the dry asphalt, the maximum longitudinal friction coefficient is jxmax=0.89 and the minimum longitudinal friction coefficient is jxmin=0.72. Matlab-Simulink software was used to investigate and compare the longitudinal friction coefficient determined by experiment and the theoretically longitudinal friction coefficient according to Ammon tire model. The survey results showed that the average error between experiment and theory was about 17%.