Static And Dynamic Analysis And Structural Optimization Of U-Type Dump Truck Carriage

Dump truck is a special vehicle that can unload goods through hydraulic or mechanical lifting mechanism.As an important load-bearing structure of dump truck,the carriage often has overloaded phenomenon,which has great impact on the performance of the whole vehicle.Therefore,the static and dynamic analysis and structural optimization of the carriage is not only the key to ensure design safely,but also an important means to detect the running condition of the vehicle,so as to realize the lightweight design of the whole vehicle.Firstly,the structure characteristics and working principle of the dump truck are introduced,the one-half degree of freedom rigid body dynamics model of the whole truck is established.The Lagrangian method is used to establish the vibration differential equation of the whole vehicle.The fifth-order natural frequencies of the vibration isolation system are calculated by MATLAB,which are 9.17Hz,14.83Hz,21.18Hz,24.89Hz and 27.44Hz respectively.The vibration characteristics of the whole vehicle are analyzed to verify the rationality of the vehicle structure.The carriage accounts for about 1/3 of the quality of the whole compartment,and the vibration characteristics of the compartment directly affect the performance of the vehicle,so the static and dynamic characteristic analysis and structural optimization of the compartment are mainly carried out later.Secondly,according to the working condition of the dump truck,the strength analysis under four typical working conditions(bending,torsion,braking and turning)is carried out on the carriage,the stress and displacement diagram of the carriage is obtained,the strength and stiffness of the carriage are checked.Under the braking condition,the maximum stress value at the contact between the longitudinal beam of the main board of the bottom board and the front beam is 113.73Mpa,the maximum deformation value of the front brim is 6.47mm,which providing a basis for the optimization design of the structure of the carriage.Thirdly,in order to avoid resonance of the car,its natural frequency should avoid the external excitation frequency.The modal analysis of the car shows that the sixth natural frequency 36.62Hz is consistent with the engine idle excitation frequency,which is prone to resonance.Based on the modal analysis of the harmonic response of the car,when the excited frequency of the car reaches 14Hz,the maximum deformation at top right edge of front cap is 4.51mm,but the deformation frequency of each node is less than the engine idle excitation,and the car will not have large plastic deformation.Then select two different pavement grades to analyze the random vibration of the car.The deformation of the front hat of the car in the Y direction is the largest,and the corresponding values are 5.77mm and 7.38mm respectively.In this regard,the structure and constraints that the cabin needs to be optimized are determined.Finally,the mathematical model of the optimization of the carriage is established.The maximum equivalent stress and maximum displacement variables of railway cars and the natural frequency of adjacent engine idle frequency were taken as the constraint conditions,and the thickness of major parts of railway cars was taken as the optimization design variable,taking the quality of carriage as the objective function.The final optimization scheme was determined,The same load and constraint were applied to the optimized compartment,and the strength,mode and random vibration were analyzed.The results before and after optimization were compared,and the overall performance of the optimized compartment was improved.The optimized rear car mass is reduced by 324kg,and the car mass is reduced by 10.2%.The lightweight design of the whole vehicle was realized by reducing the carriage quality.