Design Of Mining Dump Truck’s Suspension System Based On Two Phase Flow

With the development of the national economy,mining dump truck is more and more widely used in large open-pit mines,but with the bad working conditions and large capacity,it has bad riding comfort and handling stability.Suspension transfers the force and moment between the frame and the wheel,directly affects the riding comfort and handling stability of the vehicle.Therefore,to design the suspension for mining dump truck has important economic and engineering practical value.Suspension system consists of guide mechanism,spring and damper.Mining dump truck drives on the bad roads,whose kinematics character is poor.Mining dump truck drives on the bad roads,causes kinematics problems such as running deviation and tire wear,so it is important to design guide mechanism that decides kinematics characters.Hydro-pneumatic spring is widely used in the mining dump trucks,which consists of gas spring and oil damper,however there is little research about gas-liquid interaction of hydro-pneumatic spring,so it is difficult to describe the mechanical properties accurately.In this paper,through the model of two-phase flow,the dynamics simulation of hydro-pneumatic spring inner flow field was conducted,and the valve structures of hydro-pneumatic spring was designed based on the riding comfort.The main research contents of this paper include:1、Suspension kinematics characteristics were discussed,then analyzed the original guide mechanism,to get the reason of mining dump truck’s running deviation,tire wear and breakage of A-type frame.Double wishbone suspension that could satisfy the requirement of suspension kinematics was obtained,to provide the system basis for hydro-pneumatic spring design.2、Established the semi-empirical formulas of hydro-pneumatic spring with considering high pressure and high resistance characteristics.Mining dump truck has heavy load,in the hydro-pneumatic spring,oil and gas contact,of which the pressure can be up to tens MPa,so the elastic force model was built with considering the solution of gas and using the state equations of real gas.Because of the complex hydro-pneumatic spring,the damping force formula was built with considering the initial period of damping and local resistance,then the semi-rational formulas were verified by experiment.This chapter used for providing theoretical basis for analysis and optimization of the hydro-pneumatic spring.3、Nonlinear stiffness and damping characteristics of hydro-pneumatic spring were obtained base on the riding comfort through research and optimization.According to the characteristics of large changes between empty and full loaded,to meet that partial natural frequency should be consistent,the nonlinear stiffness characteristics following by the load change was designed.By using partial natural frequency values and the polynomial coefficients of damping force in compression and tensile phases as optimal variables,the vehicle riding comfort was optimized,then nonlinear mechanics characteristics of front and rear hydro-pneumatic springs were obtained based on the vehicle riding comfort,to provide the basis for hydro-pneumatic spring internal structure design.4、In order to make hydro-pneumatic spring match well with mining dump truck to give full play to the nonlinear mechanical properties,it is essential to design the valve structures of hydro-pneumatic spring.By using flow field analysis software-Fluent to simulate the tensile and compression strokes of hydro-pneumatic spring through the use of two phase flow,dynamic grid and UDF,the valve structures of hydro-pneumatic spring based on the riding comfort’s mechanical properties of hydro-pneumatic spring was designed.