Dynamic Analysis Of Rigid-flexible Coupling Of 21.5T Hydraulic Excavator Based On Virtual-real Technology

The hydraulic excavator is the main construction machine in the engineering operation,and the working device is the executing mechanism of the excavator to complete the excavation operation.The performance of the excavator affects the overall working efficiency and safety reliability of the excavator.In the actual operation process,due to the harsh working environment and the diversity of the excavating medium and the variability of the posture of the working device during the excavation process,it is difficult to accurately calculate the excavation resistance of the bucket during the operation,In turn,the load on the various components on the work device is inaccurate.Based on the above problems,this paper takes a 21.5T backhoe hydraulic excavator as the research image,uses the discrete element method to calculate the excavation resistance of the bucket under various working conditions,and flexes the working device,further analyze the dynamic characteristics of the working device during the operation.The main contents of the paper are as follows:(1)Establish a three-dimensional model of each component of the working device,import it into multi-body dynamics software,create a constraint relationship between the various components,and use the hydraulic cylinder data of the boom,stick and bucket as experimental driving,simulate the motion state during the operation of the working device.The movement track of the tip of the bucket,the movement law of the bucket center of mass and the relative rotation change of the bucket hinge point are analyzed.(2)According to the domestic and foreign literatures,six kinds of earth-rock mixtures and related parameters were compiled.Based on the discrete element method and EDEM software,six excavation working conditions with different shapes and sizes of stones were established.According to the obtained bucket movement parameters,the movement trajectory is set to simulate the interaction state of the bucket with the material during the excavation process.The excavation load received by the bucket during a complete excavation operation under six working conditions was obtained and compared.(3)After the boom and the arm in the working device are flexed,the corresponding rigid body is replaced,and the obtained excavating load is added to the center of the bucket.Afterthe simulation calculation,the dynamic characteristics of the working device are analyzed,and the stress state of each hinge point on the working device and the stress state of each structure are obtained,and the maximum stress moment and maximum stress position of the working device during excavation under six working conditions are determined.Point out the dangerous parts on the working device to provide a more accurate basis for the structural design and optimization of the working device.