A rectangular finite element for moderately thick flat plates

This paper presents the development of a straightforward displacement type rectangular finite element for bending of a flat plate with the inclusion of transverse (or lateral) shear effects. The element has 21 degrees of freedom consisting of nine for the lateral displacement of the midplane and 12 for rotations of the normal to the undeformed midplane of the plate (six each for rotations about the x and y axes). The latter are taken as independent of the slopes of the deformed midplane in order to include deformation due to transverse shear. The element is fully conforming and may be orthotropic. At interelement boundaries, the element matches adjacent elements both with respect to lateral displacement of the midplane and the rotations of the normal. Numerical computations for a number of examples are presented. The results show the element to be more flexible than most other finite element models and agree closely with those from a numerical solution of the three dimensional elasticity equations. The results also converge to those from thin plate theory when the thickness to length ratio becomes small or when the transverse shear moduli are artificially increased.