Through CATIA, the 3D digital model of tractor gearbox shell casting is established, and the line 3D digital model is directly imported into HyperMesh finite element software for pre-processing operations such as geometric cleaning, meshing and boundary constraints. On this basis, the free mode calculation of tractor gearbox shell casting is carried out, and the calculation results are compared with the experimental mode, as well as the static structural strength calculation of tractor gearbox shell casting, Through the calculation results of static strength structure, the topology optimization of tractor gearbox shell casting is carried out, and the lightweight of tractor gearbox shell casting is completed.
Main research results:
(1). On the basis of reading a large number of domestic and foreign literature, I learned about the research status of lightweight of tractor gearbox shell casting and the basic theoretical knowledge of structural optimization design. On the basis of consulting with tutors and experts, I determined to carry out finite element structural strength analysis through tractor gearbox shell casting, and carry out topological optimization design on this basis.
(2). CATIA software is used to accurately model the casting of tractor gearbox shell according to the drawings. Firstly, HyperMesh finite element software is used to reasonably simplify the model, and then the finite element model of tractor gearbox shell casting is established; Finally, the free modal analysis calculation and modal test verification of the gearbox are carried out. The results show that the experimental modal results are basically consistent with the calculated modal results, of which 5 orders are basically consistent, the error is basically within 6%, and the occurrence order of the consistent vibration modes is basically the same, so as to verify the accuracy of the finite element model of tractor gearbox shell casting.
(3). The stress of each bearing hole and the influence of other parts on the tractor gearbox shell casting under the working conditions of first gear and reverse gear are analyzed. Based on this, the tractor gearbox shell casting is statically analyzed. The analysis results show that the positions with the maximum stress and deformation appear near the three diaphragm positions of the tractor gearbox shell casting, the connection between the shell and the engine and the connection between the shell and the rear axle housing respectively. The maximum stress is 78.90mpa, which is less than the allowable stress of the shell material of 124mpa. Moreover, the stress in other parts of the tractor gearbox shell casting is relatively small, and the maximum deformation is 0.06985mm.
(4). During the topology optimization design of tractor gearbox shell casting, it is necessary to ensure that the performance of the optimized structure is not different from that before optimization. The optimization methods such as material redistribution and stiffener arrangement are carried out. The weight of the improved box is 148.4kg, which is reduced by 16.4kg from the original 164.8kg, and the overall reduction is about 9.95%. Finally, the free mode calculation and static strength calculation of the optimized structure are carried out to verify the performance of the improved structure.
To sum up, the static analysis is carried out by using the finite element method on the basis of verifying the correctness of the finite element model. On this basis, the lightweight design of the tractor gearbox shell casting is carried out by using the topological optimization method.