Finite element modeling of stiffened and unstiffened orthotropic plates

A finite element analysis is carried out for the bending and buckling of unstiffened, sandwich and hat-stiffened orthotropic, rectangular plates. Systematic calculations are performed for deflection, stress and critical buckling load of the plate using first order shell elements, and first and second order three-dimensional solid elements. The calculated results are compared with available analytical solutions for unstiffened plates. First-order shell and second-order three-dimensional solid elements are found to model accurately bending and buckling of the plate structures, but first-order three-dimensional solid elements give very inaccurate, inconsistent results even when the mesh density is high. For thin, unstiffened plates, one layer of second-order three-dimensional solid elements through-the-thickness is found to give sufficient accuracy. The same is found to be true for thin sandwich plates using one layer of second-order three-dimensional elements for each of the skins and one layer for the core. For a hat-stiffened plate clamped along the short edges and simply supported along the long edges, the first buckling mode occurs in the region between the stiffeners. Different approaches for joining the stiffeners to the plate are discussed. (C) 1997 Published by Elsevier Science Ltd.