Research And Implementation Of Accurate Modal Superposition Method Of Complex Modal

Vibration is widespread in daily life and production engineering, and the harmonic response analysis has important engineering significance in vibration, noise control and other fields. Thereby, increasing the efficiency and accuracy of harmonic response analysis is extremely important in the value of engineering. Among the practical engineering, mechanical systems are handled generally in accordance with the non-proportional damping system. However, the theory for solving the dynamic response of the current mechanical systems is mostly based on non-proportional damping and no damping systems, and has a larger problem truncation error and accuracy difficult to control, there is really a larger truncation error and it is difficult to control the accuracy. Therefore, based on the accurate modal superposition method of complex modes, there is the important significance in researching and developing the system for solving the dynamic response of the non-proportional damping system in practical engineering applications.Firstly, in this thesis, the development history and research status of solution techniques about the dynamic response of non-proportional damping system are described and summarized. The characteristics of the direct frequency response method, the mode superposition method and the accurate modal superposition method of complex modes are analyzed and compared. The principle of accurate modal superposition method, the solving procedures of the algorithm, and the implementation process are further introduced. When this method is used, as long as all the lower modes could be got availably within the range of required maximum excitation frequency, a converged solution can be obtained with the method. At the same time, it is more important that the method uses the physical space instead of converting to state space. Thus, in order to avoid the defect of using the state space, it is also said that the method greatly improves the efficiency of the calculation and reduces memory space. Therefore, there are more advantages to use the method to solve the dynamic response of non-proportional damping system with better accuracy and efficiency.Secondly, the technique of implement of accurate modal superposition method of complex modal is studied. In this paper, the computing system for solving the dynamic response of non-proportional damping system is developed, by a comprehensive path based on DMAP language and C++ language. DMAP language is used for implementing the algorithm, and develop the suitable sequence for solving systems; C ++ is used to set up the user environment and post-processing for the image display.At the same time, the combination of the solving steps and the implementation process of the method, the related functional modules are designed.Finally, the system is verified by the two representative examples. The results indicate that the system has better performance on the terms of accuracy and efficiency.