Formulation of flexibility-based component mode synthesis for transient analysis

Flexibility-based component mode synthesis (F-CMS) is one of the most popular free-interface component mode synthesis (CMS) methods. In the F-CMS method, localized Lagrange multipliers are employed along the interface boundary as a constraint condition between substructures; thus, it offers various advantages, including the perfect independence of subdomains, the easy treatment of the incompatible interface mesh, and parallelized formulation. However, the use of the Lagrange multipliers requires nonstandard specialized eigenvalue analysis procedures. This, in turn, requires a considerable modification in the standard displacement-based time integrators for transient analysis by using the F-CMS method. In the present study, the localized Lagrange multipliers are condensed by exploiting residual flexibility, and this results in a standard displacement-based reduced-order model. A report is made of the performance of the proposed method as compared to several CMS methods, with favorable features observed for the proposed method.