Composite Structures 11 (1989) 167-182 Inter-ply Rotational Compatibility for Composite Plates A. N. Palazotto, R. L. Hinrichsen Department of Aeronautics and Astronautics, Air Force Institute of Technology. Wright-Patterson AFB, Ohio 45433, USA & W. P. Witt Kirtland Air Force Base, NM 87117, USA ABSTRACT Through-the-thickness shear effects have been consMered within a new finite element incorporating two methods of handling interply compatibility as well as large displacements. The first method is based upon a slope and displacement continuitv while the second method is formulated with a curvature continuity. Both methods can be incorporated into a general finite element description. The results indicate some promise in describing the interlaminar characteristics of laminated plates. Large displacement solutions are carried out considering transverse loading in addition to collapse in-plane loading for rectangular plates. INTRODUCTION This paper presents a quasi-three-dimensional approach to a plate analysis in which through-the-thickness shear is considered. Large displacements are included with composite laminate constitutive relations. Two basic concepts have been published L2 that meet the smoothness and continuity conditions at the lamina interfaces, The first approach (method 1) 1 is one in which the displacement and the in-plane displacement derivatives with respect to the thickness direction are forced to be equal at the ply boundaries. The second approach (method 2) 2 forces the interply faces to have compatibility between displacement and second derivative of the displacements. The two methods create a compatibility relationship that yields shear strains and 167 Composite Structures 0263-8223/89l$03,50 © 1989ElsevierSciencePublishers Ltd, England. Printed in Great Britain