Lightweight design of chassis frame for motor boom sprayer

Abstract: Traditional optimization design ignores the effect of noise and design variables, which would make the objective function out of range, and excessive reliance on safety factor can also cause redundancy optimal design. Therefore, it is particularly important to set up design parameters properly in frame structure design stage, which can ensure the robustness of structure. With the development of computer technology and finite element theory, computer aided engineering technology is widely used in industries such as aerospace, automotive, and a large number of results have been achieved. The method which using advanced finite element software to analysis vehicle structure and integrating theoretical analysis and experimental results to perform optimal design for vehicle is becoming an important part for product development.YTT-1000 type of motor boom sprayer is a new type of boom sprayer, which is mainly used for orchard spraying and plant protection. In order to solve current problems that frame of motor boom sprayer are too heavy and fuel consumption ratio are exactly high, carbon emissions are too much and so on. A type of motor boom sprayer frame was studied in the paper, and the mesh generation software Hypermesh was used for its finite element modeling. Then the model was imported to Finite Element Analysis (short for FEA) software Radioss to do free modal analysis, the experimental modal analysis of frame were also carried out. Through modal analysis, natural frequency and mode of the frame was calculated, all these calculated results then were compared with experimental data, and the correctness of modal was verified. To calculate stress distribution and deformation of frame under bending condition and limited torsion condition, static analysis of frame were performed. The static analysis results showed that the max von mises stress under these two conditions were 182.5 and 204.5 MPa, which were still less than the specified value 235 MPa; the max displacement value were 2.97 and 4.42 mm, which were still less than the specified value 10 mm.Based on the results of FEA, a frame model of optimal design was established, and one more reasonable lightweight design proposal was made by calculating. The results showed that through the optimization, the weight of frame decreased 40.4% from 116kg to 69.1kg, and the lightweight objective was met basically. Besides, through the structure improvement, safety factor under bending condition increased 9.7% from 1.29 to 1.41, safety factor under limited torsion condition increased 7.8% from 1.15 to 1.24, and the max von mises stress under bending condition and limited torsion condition decreased by 8.9%(from 182.5 to 166.3 MPa) and 7.2%(from 204.5 to 189.7 MPa), respectively. The max displacement under these two conditions increased 9.8% and 5.2%, respectively. Although the max displacement was increased, these values still less than the specified value 10 mm.Given the complicated operating conditions of motor boom sprayer, and most of the frame structure damage was caused by fatigue failure. Therefore, a series of fatigue testing under random loading and fatigue failure analysis of frame will be carried out in the future. This study may provide a reference for enterprise to do research on motor boom sprayer.