Dynamic Condensation Technique For Computing Several Low Order Modal Pairs

Structural dynamic condensation technique has been broadly applied to many fields such as eigenvalue analysis of large and/or complex structures, dynamic updating of finite element models, structural damage detection, parameter identification, test-analysis model correlation, modal testing, active vibration control, dynamic substructure technique and so on.One of the oldest and most popular reduction methods is static reduction proposed by Guyan and Irons. After this, a lot of work have been done in this area and many efficient static and dynamic condensation methods have been proposed at home and abroad especially at abroad. However, many problems, pertaining to the valid limits, computational work, dynamic condensation accuracy and convergence, prevent the technique from being used efficiently in these fields. Hence, dynamic condensation technique has been improved and consummated in the following areas:1. A general expression of the transformation between master and slave degree of freedoms was derived from the power series expansion of the matrix. The general expression was also expressed as a power series of the unknown eigenvalues. After that, the validity and convergence of the condensation method were analyzed. For the accuracy of this eigenproblem resulted from the dynamic condensation, this method is compared with the inverse power method.2. For the condensation method computing several eigenvalues simutaneusely, a sufficient condention was derived by solving matrix...