Research And Implementation Of Modal Synthesis Based On DMAP

Modal synthesis is a method which can calculate dynamic characteristics of an assemblystructure according to modal data of its substructures. The principle of modal synthesis is todivide a large and complex structure into several substructures. The modal data of thosesubstructures can be obtained either by numerical method or experimental method. In order topromote engineering application of modal synthesis, the theory and techniques involved intothe implementation of modal synthesis system was studied in this dissertation.Firstly, the status of modal synthesis was reviewed. The basic algorithm of modalsynthesis was introduced. A formula of the secondary coordinate transformation with rigidconnection was formulated. The method of processing flexible connection was studied. Thetechniques of model reduction and correlation were studied too.Secondly, the technique of implement of modal synthesis was studied. A procedure ofimplement of modal synthesis based on DMAP and VC++was proposed and a system wasdeveloped. Modal synthesis was implemented relied on the computing capability of Nastran.Meanwhile, related functions including model reduction and correlation analysis wereimplemented too. A unified data structure was designed and the key algorithms weredeveloped.Finally, the system was verified by some examples. The results showed that the system isefficient.