Partitioned solution of reduced–integrated finite element equations

This paper presents an algorithm for using reduced–integrated elements in structural modeling and analysis. A novel feature of the present algorithm is an element-by-element hourglass-mode projection instead of stabilization. The present algorithm is well suited to parallel computations and exploits the salient features of a recently developed direct flexibility method (DFM) that employs the substructural deformations as one of the primary variables. The total displacements are obtained as sum of the elemental deformations and rigid-body motions while hourglass modes are projected out employing only elemental hourglass modes. Thus, reduced integrated elements can be used for stress analysis without hourglass-mode stabilization when one employs the DFM. Examples illustrate the basic features of the present algorithm.