Research On Lightweight Design Of Chassis Frame Of Crawler The Rice Combine Harvester With 5kg/s Feed Rate

Recently,lightweight design has been widely used in the field of engineering machinery with the pressure of energy crisis and environmental protection.However,as a large country that uses agricultural machinery,the lightweight design of my country’s agricultural machinery has just begun.At present,the process of agricultural mechanization in my country is constantly advancing,especially the crawler combine harvester has been developed rapidly.As the core support component of the combine harvester,the chassis of agricultural machinery carries the main working components such as the header,the conveying trough,the cab,the chassis frame,the crawler,the engine,the threshing and cleaning device,and the grain tank.In addition,the chassis frame also needs to withstand the impact of the road surface and external loads when the combine harvester completes field operations.The weight and performance parameters of the chassis frame have a vital impact on the whole harvester.Until now,most of the chassis design of agricultural machinery has still depended on traditional experience.The strength of chassis frame structure still has a large space for optimization.Therefore,the lightweight design of the chassis of agricultural machinery is of high practical significance.In this paper,the chassis frame of the crawler rice combine harvester with a feed rate of 5kg/s is used as the research basis.Under the premise of ensuring the overall strength,rigidity and dynamic characteristics of the frame,the chassis is optimized by the use of lightweight materials and advanced optimization algorithms.The main research contents are as follows:(1)Establish a three-dimensional model of the chassis frame of the rice combine harvester and simplify the model.After simplifing,the model is processed many steps,such as the division of mesh attributes,the assignment of material attributes,the addition of loads and boundary conditions.According to the four classic working conditions(bending,torsion,braking,and sharp turning)of the harvester in the field,corresponding constraints are added to solve the maximum stress and displacement cloud diagram of the chassis frame.In the end,the strength and stiffness of the chassis frame are verified according to the analysis results.(2)The unconstrained modal simulation analysis of the chassis frame is carried out through the finite element software,and the modal shape and natural frequency of the first 6-order nonrigid displacement of the chassis frame are obtained.The low-order natural frequency of the frame is analyzed and compared with the excitation frequency of the engine and the road surface of the frame to verify the rationality and stability of the frame structure.Use hammer,DH5902 data acquisition instrument and DHDAS dynamic signal analysis system to carry out dynamic modal test test on the chassis frame,and measure the test modal parameters of the frame.The simulation results and the modal test results are analyzed and compared to verify the rationality of the dynamic characteristics of the frame and the finite element analysis.(3)Using topology optimization to optimize the shape of the frame,the precondition is to retain 85% of the original mass of the frame,and the topology optimization calculation of the frame is performed,and the redundant material distribution area of the chassis frame is solved after multiple iterations.In the redundant position of the material,the weight-reducing hole design,the optimized design of the frame beam section and the optimized design of the local support are used to optimize the structure of the chassis frame.The optimized chassis frame is analyzed and verified by strength,rigidity and modal characteristics to verify the rationality of the optimized frame design.(4)Taking the optimized chassis frame as the research object,firstly optimize the material technology,and adopt the multi-objective lightweight design based on genetic algorithm for the cross-sectional thickness of the optimized frame rectangular beam.Taking the quality,maximum stress and maximum displacement of the frame as the design goals,the frame beams are screened for sensitivity,and then the space filling design test method is selected,and the Kriging approximation model is used to optimize the thickness of the rectangular beams of the chassis frame.The optimization results are remodeled and analyzed to verify the strength,stiffness performance and modal characteristics of the chassis frame after multi-objective optimization,and finally to verify the lightweight effect of the chassis frame.