- The nonlinear version of the generalized laminated plate theory of Reddy is presented, and it is used to investigate nonlinear effects in composite laminates. A plate-bending finite element based on the theory is developed, and its accuracy is investigated by comparison with exact and approximate solutions to conventional plate theories. The element has improved description of the in-plane as well as the transverse deformation response. The theory is further applied to study various aspects of the geometrically nonlinear analysis of composite plates. It is shown that inclusion of the geometric nonlinearity relaxes stress distributions and that composite laminates with bending-extensional coupling do not exhibit any bifurcation (i.e., no apparent critical buckling load exists). 1990 American Institute of Aeronautics and Astronautics, Inc., All rights reserved.