Eliminating interface degrees-of-freedom in substructuring

In standard substructuring methods, which are used to reduce the order of large finite element models, a structure is partitioned into several substructures that share certain nodes (interface nodes) at their boundaries with each other. When a substructuring technique is applied to a structure, the interface nodes or a transformation of them remain in the reduced model. Keeping the interface nodes, if they are relatively high in numbers, in the condensed model reduces its computational efficiency. The computational efficiency of the condensed model could be increased if those nodes are eliminated from the model. In this paper a different method of substructuring is presented which enables the elimination of the interface DoF. The new method incorporates a different strategy in partitioning the structure into its substructures, allowing this elimination. This provides a great tool in constructing condensed finite element structures with much less total number of DoF compared to cases where a standard substructuring is used. In this paper the new method is explained for structures with two components. As an application this method is applied to a FE tire model and its results are compared to those of standard substructuring.