A Superelement Formulation for Mechanism Analysis

ALBERTO CARDONA; MICHEL GERADIN

COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING

ELSEVIER SCIENCE SA

Año: 1992 vol. 100 p. 1 - 29

0045-7825

A superelement formulation capable of handling large finite rotations is developed. The term'superelement' in finite element technology, refers to numerical models obtained by condensation of a large finite element mesh (Crisfield). In this paper, this technique is generalized to building numerical models of mechanism members from information computed in a linear vibration analysis program. This model can afterwards be used to analyze mechanism members undergoing large arbitrary rotations in three-dimensional space. The formulation is based on a small rotation and displacement hypothesis in a local frame to the superelement. The standard component-mode approach is adopted together with a lumped mass inertia approximation. The resulting degrees of freedom of the formulation are the positions and orientations at the so-called boundary nodes of the superelement, plus a given number of internal mode amplitudes. Finite rotations are fully accounted for, the formulation of the superelement being also able to include rotary inertias. Rotations are parametrized by using the rotational vector.