The deformation mode of the structure is determined by the external vibration mode of the tractor, and the deformation mode of the structure itself is the same as the vibration mode of the structure under the same constraint. The most important thing for modal analysis is the identification of modal parameters. In practical engineering problems, the vibration mode and frequency data of a certain order of the structure are obtained through CAE analysis software, which can avoid resonance with other vibration sources or actively avoid some specific frequencies.
According to the different constraint States, the modal analysis of tractor gearbox shell casting can be divided into constraint modal calculation and free modal calculation. Free mode refers to the mode calculation of the finite element model without any load and constraints. The first six modes of the free mode calculation results only have rigid displacement, and the natural frequency is almost zero, which is a rigid body mode; It has research significance from the 7th order, which is elastic mode. Constrained mode is to identify the modal parameters under the simulated actual load and constraint conditions. The first six orders are not zero, and the results are consistent with the actual situation.
The free mode and constrained mode analysis of tractor gearbox shell casting is completed in HyperMesh. Because the low-order mode has a great impact on the system vibration, set the range of free mode frequency and constrained mode frequency to 0 ~ 2000Hz, compare the free mode calculation results with the test results to verify the correctness of the finite element model, and compare the dynamic characteristics of the front and rear structures through the constrained mode.