Rigid-flexible Coupling Modeling And Dynamic Analysis Of Key Components Of Bulldozer Working Device

Bulldozer,as one of the most important products in the field of construction machinery,is widely used in the construction of national infrastructure.The working environment of bulldozer is bad,and the working conditions are complex.As the main load bearing unit,the front work device will exhibit different dynamic characteristics under complex conditions.The dynamic response of launching bridge and lifting cylinder will have an important influence on the performance of the bulldozer’s working device.Therefore,in order to grasp the dynamic characteristics of the former working device under complex conditions,this paper takes a large bulldozer working device as the research object,establishes rigid flexible coupling model for working device and mathematical model of the stiffness and damping of the hoist oil cylinder analyses force changes at the key hinge points and the dynamic characteristics of the lifting cylinder,and the main contents are as follows:First of all,this paper introduces the structure of the former working device,and calculates its space freedom of motion to determine its two ways of lifting and tilting.According to the structure and performance parameters of the working device,this paper creates the model of the front working device.Four working conditions of the working device are analyzed,including roll over,full load,lifting and cutting pushing with a shovel,and mechanical equation under the condition of rollover,the stress state of the shovel under the condition of full load,the kinematic equation of lifting mechanism under lifting condition and resistance equation on the blade of a bulldozer blade are obtained.Secondly,flexible treatment of launching bridge,a rigid flexible coupling virtual prototype model of the working device with launching bridge as a flexible body is established.In the working condition of linear earth pushing operation,bulldozer working device is simulated,and the stress change at a point in the middle of launching bridge is obtained,which verifies the accuracy of the model.At the same time,the stress changes at the hinge point of the rigid and flexible launching bridge and the bulldozer and the hinge point of the hoist oil cylinder and the blade are obtained.The comparison results show that the working device will be affected by the larger vibration when the load is subjected to the load and the load is abrupt.And the change trend is consistent with the actual operating conditions.The conclusion is that the key components and hinges of bulldozer’s working device will be affected by vibration under the dynamic load.Lastly,mechanical analysis of the working device is carried out,and mathematical model of the lifting cylinder’s acting force is obtained in the paper;combined load pressure equation of cylinder and flow equation,the dynamic characteristic model of the stiffness and damping of lifting cylinder is established.The effect of the equivalent mass and the external excitation frequency on the dynamic characteristics of the oil cylinder is analyzed and effect of equivalent mass and external excitation frequency on dynamic characteristics of cylinder is analyzed.At the same time,the influence of the hydraulic oil leakage coefficient on the stiffness and damping coefficient of lifting cylinder is studied.This study can provide reference for dynamic characteristics analysis of key components of bulldozer working device.