Large Deflections of Orthotropic Plates in Compression

Rectangular specially orthotropic plates subjected to uniaxial in-plane compression are analyzed into the large deflection regime, using the computer program ELDAROP. All four edges are simply supported against out-of-plane movement, and opposite pairs of edges are maintained straight and parallel. Some plates analyzed are initially flat. Others have a geometrical imperfection shaped as a single half-sine wave in both directions. Particular attention is given to the effects on plate behavior of the modular ratio $E_x/E_y$, and the geometrical imperfection amplitude ${\Delta }_O/t$. For flat plates, the initial postbuckled stiffness depends entirely on the membrane rigidities and the aspect ratio $a/b$. However, on further loading, the bending rigidities then have a significant effect, provided the membrane behavior is not close to being isotropic.