HYBRID HEXAHEDRAL ELEMENT FOR SOLIDS, PLATES, SHELLS AND BEAMS BY SELECTIVE SCALING

A robust two-field hexahedral element capable of handling plate/shell, beam and nearly incompressible material analyses without locking are presented. Starting with the assumed stress element of Pian and Tong,7 parasitic strain components leading to locking in plate, shell and be am analyses are first identified. Locking can be alleviated by scaling down selectively the parasitic strain components in the leverage matr ix. Unfortunately, the element then fails the patch test. However, pat ch test correction and reduction in computation can be achieved by the recently proposed admissible matrix formulation. The resulting elemen t is lock-free and very efficient. All matrices involved in constructi ng the stiffness matrix can be derived explicitly. The accuracy of the element is tested by popular bench-mark problems.