Large Deflections of Orthotropic Plates under Pressure

Rectangular specially orthotropic plates subjected to uniform lateral pressure are analyzed into the large deflection regime, using the computer program ELDAROP. All four edges are supported against out‐of‐plane movement, with either simple support, or clamping, all round. With regard to the in‐plane boundary conditions, all four edges are either free to pull in straight, or completely restrained from normal movement. Some plates analyzed are initially flat. The others have a geometrical imperfection shaped as the first term in the series used to represent the lateral displacement. A positive imperfection means that the pressure is applied to the concave surface. Particular attention is given to the effect on plate behavior of the modular ratio $E_x/E_y\text{,}$ the aspect ratio $a/b\text{,}$ the geometrical imperfection amplitude ${\Delta }_0/t\text{,}$ and various combinations of boundary conditions. Negative as well as positive imperfections are considered; certain negative ${\Delta }_0/t$ cases exhibit snap‐through behavior when the edges are fixed in‐plane. Of the design parameters that control plate behavior, the normalized aspect ratio $(a/b)(E_y/E_x{)}^{1/4}$ is shown to have the dominant effect for the cases analyzed.