Lightweight Design And Dynamics Research Of Chassis Frame For Orchard Electric Tracked Vehicle

Developing small-sized orchard transport machines has a great significance to improve the efficiency of fruit harvest and the level of orchard mechanization.In order to fulfill the flexibility,portability and energy saving requirements of orchard transport chassis,an electric remote control crawler chassis was designed,the finite element method of chassis frame was developed and verified,and lightweight design of the chassis was developed by finite element calculation method.Moreover,a dynamic simulated model was developed and verified,based on the model the dangerous points of the chassis frame under particular conditions were simulated.Finally,the finite element calculation check of lightweight designed frame was done by combining dynamic and static simulation software.The main contents and results are as follows:(1)An electric tracked vehicle was carried out which main parameters were calculated,and explained the layout of power units.(2)The finite element model of the crawler chassis frame was constructed,and the frame loads were determined reasonably based on the actual situation of each dynamic component,and the stress-strain distributions of bending and torsion conditions were obtained by finite element calculation method.The stress values of the six measuring points of the frame were obtained by the static electric test which was the same as the finite element calculation results.Selected the bottom frame as the object,the lightweight design was carried out by structural optimization.After that the frame structure was redesigned according to the optimization result,and the finite element calculation check of redesigned frame under bending and torsion conditions was calculated.The results showed that the frame after the lightweight design can fully satisfies the bending and torsion conditions in the course of the chassis operation,meanwhile the quality of the frame was reduced by 8.82%.The fatigue life of the lightweight frame was analyzed by ANSYS Workbench.The results showed that the minimum fatigue life is about 58713 h which was much longer than theoretical calculating value 36500 h,occurring in the dots connecting beam and the track bearing.(3)The dynamic model of the crawler chassis was constructed,and a chassis vertical acceleration comparison of accelerating simulation and experiment under static acceleration condition was carried out.The results showed that variation tendency of simulation chassis vertical acceleration was same as experiment values.The crossing ability of crawler chassis and impulse loads of chassis under ramp climbing of 30?and trench crossing were analyzed in dynamic simulation environment.The results showed that the crossing ability was better and impulse load of the first bearing wheel was about 3700 N under climbing condition and the second bearing wheel impulse load was about 4000 N under trench crossing condition.And the finite element calculation check of the frame under the impulse loads was simulated.The results showed that the maximum stress and strain of the frame under the impulse load were increased,but still within the range that the frame can bear.(4)The force function formula of track tension was established with the rear-drive.The example simulation results showed that the track tension changed periodically,the track tension result was different while it was in different positions.