Study On Flexible Truss Boom System Design And Dynamic Simulation

For a long time, it has been a big problem to control the pests and disease of hi-crops effectively. Super high clearance self-propelled sprayer was designed to solve this problem. However, for the boom is positioned over 2.5m height, and the field environment is complex, the boom vibration is inevitable, and thus would greatly affect the spray uniformity. How to design the shock mitigation system and how to make the boom always keep balance has become a key problem.Based on the practical projects of'Research on Pesticide Application Technology and Equipments of Hi-crops'and'State Key Laboratory of Soil—Plant—Machinery System Technology', the study on flexible truss boom system design and dynamic simulation is presented in this dissertation. It includes six parts, namely, dynamic test system design of the boom, static FEA for the expanding boom, flexible truss boom modeling, lab simulation and field simulation of the sprayer, kinematic equations of flexible multi-body boom, and isosceles trapezoid suspension design.To satisfy the requirements of the project'State Key Laboratory of Soil—Plant—Machinery System Technology', SDF test platform was established. According to the requirements of the dynamic characteristics of collection points, the distribution of collection points was designed. Acceleration sensors and displacement sensors were chosen for the system requirements. Data collector, data conditioner and system software were developed also. With this test system, the boom's field vibration tests for several types of sprayers were carried out, which obtained two necessary conditions to make the kinetic boom keep stable and balance. First, a suspension of good performance should be positioned between the boom and body frame. Second, flexible connections between trusses should be used to absorb the impact force.According to the requirements of the project and field test results, the 24m width truss boom system was designed, and FEA method was used to analyze the expanding truss boom. The results show that the boom design is reasonable, and the chief results are as follows: The maximum stress intensity of big arm is 104.8MPa, middle arm 20.5MPa, and small arm 25.9Mpa, far lower than 620MPa yield strength. The displacement of big arm is 8 mm, middle arm 0.017 mm, and small arm 0.8 mm. The maximum strain of big arm is 0.0007, middle arm 0.00007, and small arm 0.00007. The minimum safety factor of big arm is 1.5, middle arm 10.7, and small arm 8.5, greater than 1.0.By ADAMS virtual prototyping technology, the prototype 3WZC-2000 super high clearance sprayer was modeled and simulated. To compare characteristic parameters of the boom with or without a suspension, the sprayer was simulated during left wheel jouncing in the lab simulation environment. To get more real dynamic characteristic parameter curves, tires and field road spectrum were established. The result shows that the suspension can make the kinetic boom more stable.Motion equation of the flexible multi-body boom was derived to test the suspension system of boom. It shows that suspension can keep the boom stable when the tractor moving fast.The theory of changing just one lever of the isosceles trapezoid suspension of the kinetic boom was advanced and equations were derived. It was used on the sprayer. The results show that the theory is reasonable, and one lever changing suspension is able to keep the kinetic boom stable greatly.