Efficient Component Mode Synthesis with a New Interface Reduction Method

When the finite element model of a complex structure is partitioned into substructures in order to enable component mode synthesis (CMS), there may be a large number of degrees of freedom (DOF) on the interface between components. In such a case, the constraint-mode-related coordinate transformation at the substructure analysis stage becomes computationally expensive, and the CMS model may be cumbersome due to the interface DOF that dominate the model size. A more compact model can be obtained using a previously introduced method for reducing the interface DOF. This method involves an eigenanalysis performed on the interface partitions of the CMS matrices, followed by an interface mode selection. However, because the interface matrix partitions usually have high densities, this reduction process may demand a high computational cost. In this work, several alternative interface reduction methods from the literature are reviewed and compared, and a new method is proposed in which interface modes are obtained based on approximate constraint modes. With only a slight sacrifice of accuracy, the proposed method exhibits greatly improved efficiency for both the constraint-mode-related coordinate transformation required to generate the CMS model as well as any subsequent interface eigenanalysis. For an application to a large-scale finite element model of an automotive vehicle, numerical results are provided to demonstrate the performance of the method.