A QUASI-CONFORMING AND PENALTY ELEMENT OF LAMINATED COMPOSITES

Mindlin-type elements have been widely used to stress analysis for laminated composite classical thin and moderately thick plates and/or shells.However,as the ratio of thickness to span of the plates and/or shells increases,so-called "shear lockingn" becomes noticeable.To overcome the shortcoming,the present paper,by using Tang's multi-variable quasi-con-forming and penalty elements technique (QCPE) estabilished a general propose shear flexible triangular finite element for laminated composite plate,which can be afforded for practical usea.The element consists of two rotation and three displacements as generalized degrees of freedom per node.Numerical examples for bending problem are presented for plates of isotropic as well as laminated composite.From examination and discussion on numerical results,the following conclusions are given:(1) QCPE is a element with good behaviour.As the mesh is refined，the finite element solutions for both thin and/or modertely thick plates rapidly converge towanl the exact solutions.(2) The shear effect on the deflection W of laminated composite plate would be gradually strengthened as the ratio of thickness to span of the plates increases.For Graphite/Epoxy material,the shear effect becomes nonelimiable when h/a≥30.(3) The shear effect on the deflection W of laminated composite plates would be gradually strengthened as the numbers of layer decreases or the ratio of moduli E₁/E₂ increases.This pmject was supported by science fund of the Chinese Academy of Sciences.