Random Vibration Characteristics Analysis And Experimental Research Of Self-propelled Micro Tillage Machine

As a commonly used agricultural machinery in hilly areas,micro tillage machine have played an active role in promoting the level of agricultural mechanization in hilly areas.However,environment of the micro-tiller for operating is harsh,Comfort level of control and spare parts' life seriously effected by violent vibration of operation.Therefore,it is of great theoretical and demand background to study the vibration characteristics of micro tillage machine.The paper relies on the National Natural Science Foundation of China,in view of the defect in the vibration of micro tillage machine operation,using a certain type of self-propelled micro tillage machine as an object,systematically studied the random vibration characteristics of micro tillage machine,which is based on the theory analysis,numerical simulation and experimental study.The main research work is:1.Using LMS Test.Lab system tested the main structural vibration of eight speed conditions,analyzed the time domain and frequency domain.Test results show that:According to the structure of the maximum vibration acceleration order,Bumper> Engine>Engine Bracket> Handle> Transmission> Gearbox,Micro tillage machine vibration increases with the Engine speed increase.Distribution of amplitude peak frequency of each structure is not concentrated,may have resonances occur within each frequency range.2.Combined with vibration test results of micro tillage machine in non-operational state,considering the structure of the most violent vibration(bumper),direct contact with the vibration source structure(engine),and hand structure(control)as the key to the flexible body parts.The modal analysis of the key flexible parts are carried out by means of simulation and experiment,and the rationality of the corresponding finite element model is verified.3.According to the structural characteristics of the micro tillage machine and its actual connection requirements,the topological structure and the constraint relation of the micro tillage machine were determined.Based on the taper angle theory,the constraint stiffness and damping parameters of the bolt joint surface are calculated out.Based on Hypermesh and ADAMS,the rigid-flexible coupling dynamics model of micro tillage machine was established,and the rationality of rigid-flexible coupling dynamic model was verified by finite element modal analysis.4.Considering the influence of rotary tillage parts,the dynamic model of micro tillage machine is modified and improved.Based on the field test data,the optimum tillage depth range of micro tillage machine was determined,and the soil test environment was set up.On the basis of this,the excitation conditions of vibration simulation are established by means of theoretical analysis and experimental study,and the accurate measurement of random vibration response parameters of micro tillage machine is realized by simulation.5.The natural frequency of the micro tillage machine is optimized,and the natural frequency is optimized to 81.77 Hz and 177.54 Hz.The main working frequency of the micro tillage machine is 150 Hz,and the special sensitive frequency range,avoids effectively the resonance,improves the micro tillage machine control comfort.At the same time,the suggestions of structural optimization of micro tillage machine are put forward from the aspects of reducing vibration of excitation source and improving vibration transmission path.