3-D Finite Element Analysis of Curved Beams in Bending

Abstract

The effect of anticlastic curvature in pure bending of curved composite beams is investigated by finite element analysis. A full 3-D model of a slice through the beam is analysed, and also a 2-D model assuming generalised plane strain. It is shown that due to the curvature, there is restraint on anticlastic bending, giving rise to a significant variation of stresses across the width. The commonly assumed state of plane stress is therefore not strictly valid even for relatively narrow specimens. There can be significant discrepancies in fibre direction stresses and strains compared with those calculated on the basis of plane stress. As the width increases, the results at the centre of the beam approach those from the generalised plane strain analysis. This gives the same values of interlaminar tensile stresses as from the plane stress solution, but there are still differences in fibre direction strains. The results show the need for caution in interpreting strain gauge results on curved beams.