| When the wheeled tractor/plough system works in the field,the vehicle body vibration caused by rough road surface and the cutting resistance between the plough and the soil will reduce the operating stability and driving comfort of the tractor,and damage the driver’s health.In order to improve the riding comfort and driving safety of the tractor,it is necessary to establish the vibration model of the wheeled tractor/plough system and analyze the vibration characteristics under ploughing working conditions,which has important theoretical significance and engineering value for the structural design and optimization of the tractor suspension system.This paper takes the hanging CF700 tractor/plough system as the research object,establishes the vibration model of the wheel tractor/plough system,analyzes the vibration characteristics of each part of the tractor system,aims to master the influence law of the road surface excitation and the ploughing resistance in the process of ploughing,and studies the optimization of the front axle suspension parameters of the tractor.The specific work completed and main research conclusions are as follows:1)Based on ABAQUS,a finite element model of the plough-soil coupling system was established to simulate the cutting process of the plough-soil coupling system.The correctness and reliability of the established model were verified through the tractor ploughing resistance test.On this basis,the modified model was used to study the resistance curves of the plough body under different tillage speeds and depths,which provided a basis for the subsequent research on the vibration characteristics of the wheeled tractor/plough system under ploughing conditions.（2）Based on the recursive datum method,the roughness test system designed by the laboratory was used to obtain the roughness data of the farmland road surface,and the vibration model of the wheeled tractor without front axle suspension/plough system was established.The correctness of the model was verified through vibration tests.On this basis,the vertical vibration acceleration response and natural frequency of each part of the tractor are studied by using the established vibration model.（3）Constructed the vibration model of wheeled tractor/plough system with front axle suspension,the vibration differential equations are derived,the wheeled tractor/plough system are studied in road transportation,farmland and plough vibration characteristics of three kinds of working conditions and plough tillage speed and tillage depth on the influence law of wheeled tractor/plough system vibration characteristics.The simulation results show that the natural frequency of the tractor system is basically unchanged under road transport,farm transport and plow operation.Compared with the vibration response of road transport,the vertical vibration acceleration of each part of the tractor is significantly reduced under the working conditions of farm transport and plow.With the increase of plough speed and depth,the vibration acceleration of each part of the tractor system also increases significantly.When ploughing depth or ploughing speed is constant,the vertical vibration acceleration of the front axle is the maximum.（4）The mathematical model of the stiffness and damping of the front axle hydro-pneumatic spring is established,and the average value of the linearized stiffness coefficient and damping coefficient is obtained.Based on the genetic algorithm,the stiffness and damping coefficients of the optimized hydro-pneumatic suspension of the front axle are obtained to be 90.8k N·m-1and 7.48k N·s·m-1,respectively.On this basis,the vibration characteristics of the front and rear wheeled tractor/farm tool system optimized by the front axle suspension are compared and analyzed.The results show that after the optimization of the front axle suspension,the angular acceleration of the cab and the vertical acceleration of the front axle are significantly reduced,and the driving safety and operating stability of the tractor are improved. |
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