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Firstly, a finite element model which can accurately reach the dynamic characteristics of the structure is established, and the modal analysis is carried out to obtain the natural frequency and mode shape of the structure. Secondly, based on the finite element model and the analysis result, the computer program is programmed according to the sensitivity calculation formula. Structural dynamic characteristic sensitivity; finally, according to the sensitivity calculation results, according to the structural dynamic performance requirements, the power modification. Sensitivity analysis and dynamic modification of structural dynamic characteristics using finite element analysis results have many advantages: comprehensive and detailed structural inherent characteristics can be obtained, including high-order natural frequencies and vibration modes that are difficult to measure, as well as corner freedom, etc.; Sensitivity analysis of the structure to save costs and improve efficiency.
Firstly, a finite element model which can accurately reach the dynamic characteristics of the structure is established, and the modal analysis is carried out to obtain the input data (including the values ​​of each design variable and the frequency of each order and the mode shape) for the sensitivity analysis of the dynamic characteristics. In order to obtain the overall stiffness and mass matrix of the analyzed structure, all the node degrees of freedom of the structural finite element model can be combined into one ANSYS super unit, and the overall stiffness and mass matrix information of the structure is included in the generated super unit file. High-level programming language programming can be used to extract data from hyper-unit files to obtain the model's overall stiffness and overall mass matrix in the format required for sensitivity calculation. Based on the obtained data and the aforementioned sensitivity calculation formula, the dynamic characteristic sensitivity value can be calculated.
The method uses computer programming to process the data required for sensitivity analysis, and achieves universal sensitivity calculation based on finite element analysis. Since the various information of the finite element analysis result is fully utilized, the cumbersomeness of solving the stiffness and the mass matrix is ​​avoided, and the operation is simple.
The sensitivity analysis indicates the direction of the dynamic modification of the structure, and the designer can determine the system dynamic modification based on the sensitivity value. Combining the finite element technique with the power modification of the gear transmission system based on sensitivity analysis, the modification effect can be observed directly in the finite element model. The method can solve the sensitivity analysis and power modification problems of similar complex structures, and makes a useful attempt for the application of structural dynamic modification theory in engineering practice.