Research On The Lightweight Frame Of The Corn Harvester With Both Ear And Stem Harvesting

The rapid development of animal husbandry has led to an imbalance in the supply and demand of forage and feed.The corn harvester with both ear and stem harvesting has become a research hotspot in corn harvesting machinery due to its ability to simultaneously harvest ears and forage.The traditional frame design method significantly increases the use of materials to ensure the strength of the frame,making the already complex harvester more cumbersome,while also increasing fuel consumption,which is not conducive to the sustainable development of green agriculture.Once encountering muddy field roads and working plots,the harvester is prone to sinking due to its excessive quality,resulting in its inability to operate,seriously affecting the efficiency of corn harvesting operations.Therefore,as an important load-bearing structure of the entire vehicle,it is particularly important to optimize the structure and lightweight design of the frame.The main research content of this article is as follows:(1)The finite element model of the frame is established on the basis of the three-dimensional model of the whole machine.After the pretreatment of the model,the Statics analysis of the frame under full load bending and full load bending and torsion conditions is carried out,and the stress,strain and displacement diagrams are obtained.The stress on the frame is less than the material yield limit,but the stress on the frame near the front wheel is larger and the Factor of safety is lower;The stress on the rear area of the frame is relatively small,making it suitable for structural lightweight.(2)Perform modal analysis on the finite element model of the frame under free boundary conditions to obtain the first eight modes and natural frequencies of non rigid body displacement of the frame.Conduct vibration tests on the frame and obtain the acceleration amplitude of the vibration at the frame measurement points.The measurement points above the rear axle of the frame are significantly higher than other measurement points.By performing Fourier transform on the time-domain map,the self spectra of each measurement point were obtained.It can be seen that the vibration frequency of the measurement point above the rear axle of the vehicle frame caused by road roughness is similar to the first-order natural frequency of the vehicle frame,and the vehicle frame is prone to resonance.(3)According to the results of Statics analysis,select the beam with small stress on the frame,take the thickness of the beam as the design variable,take the minimum mass of the frame and the maximization of the first order natural frequency as the design goal,and carry out multi-objective size optimization of the frame under multiple working conditions based on the response surface method.After the size is rounded,the analysis shows that the stress on the frame after optimization meets the requirements,the first order natural frequency is increased by 4.89Hz,and the weight is reduced by 7.1%.Using the area with high stress at the front end of the frame as the optimization area,determine the weight of single condition topology optimization for the frame,and perform multi condition topology optimization based on the variable density method.After topology optimization,the maximum stress of the frame under full load bending and full load bending torsion conditions is significantly reduced,and the Factor of safety of the frame is improved.(4)According to the Statics analysis results after optimization,combined with the material S-N curve and load spectrum,the five block diagram of fatigue analysis is established in n Code,and the fatigue analysis of the frame is carried out,and the minimum number of stress cycles of the frame is 1.355×10~7times.After optimizing the prototype trial production,the frame vibration test and overall reliability test were conducted.The results showed that the acceleration amplitude of the measuring point above the rear axle of the frame significantly decreased,and the effectiveness of the prototype was 100%,meeting the reliability requirements.