Abstract: In view of the problem of excessive modal analysis schemes in the optimization process of complex parameter structure, an optimization method based on FEA with orthogonal design is proposed by combining the features of modal analysis and orthogonal test. Through the orthogonal test plan for the finite element modal analysis scheme of structure, the number of analysis samples is greatly reduced, moreover the analysis results of test data can determine better level of various test factors and the influence of the factors upon the vibration performance, thereby the vibration characteristics of mechanical structure can be quickly changed by changing the sensitive parameters. Finally, the handle of a small agricultural machine is taken as an example, the first order vibration frequency is changed from 41.7 Hz to 71.379 Hz, thus keeping off the sensitive frequency range of hand. The optimization and test results prove the validity and feasibility of that method.

Key words: Handle, Modal analysis, Optimization, Orthogonal experimental design