VIBRATION ANALYSIS OF ELECTRIC VEHICLE-ROAD COUPLING SYSTEM CONSIDERING TIRE-ROAD MULTI-POINT CONTACT

The unsprung mass of the electric vehicle driven by the hub motor is large, which makes the tire dynamic load increase, and the motor excitation further aggravates the wheel vibration. Meanwhile, the dynamic calculation results of the simplified model of single point contact between tire and road are different from the actual. Thus, considering the electromagnetic excitation of the motor, nonlinear foundation and multi-point contact between tire and road, the electromechanical coupling dynamic model of the electric vehicle-road system is established. The vertical vibration of the nonlinear foundation beam is derived by the Galerkin method, and the accurate expression of the nonlinear integral term in the nonlinear foundation beam is derived by using the integral sum formula. A simple method to select the truncation order of the road is proposed, which is verified with the convergence of road response. Accordingly, the effects of multi-point contact between tire and road, nonlinear foundation, motor excitation, vehicle speed and road roughness amplitude on vehicle response are studied. The results show that among the effects of nonlinear foundation and multi-point contact on the vehicle response, the tire dynamic load has the largest influence, and the vehicle body acceleration and suspension dynamic displacement have a small effect. Moreover, when the motor excitation is considered, the influence of the two on the vehicle response increases. From the perspective of the influence on the road response, the motor excitation has the greatest, the nonlinear foundation has the second influence, and the multi-point contact has the less. The established model and research method provide a new idea for vertical dynamics analysis of electric vehicles.