Distortion of U-Channel Sections in Plastic Bending

Abstract

When a thin-walled U-channel section is plastically bent, considerable in-plane distortion occurs. The initially flat base of the U is deformed into a circular arc. The sides remain perpendicular to the base so that an angle between the sides develops. In this paper, an analytical expression for the amount of distortion is derived based on energy minimization. The expression is purely geometrical indicating that distortion should not depend on material properties. The theory is compared with fourpoint bending experiments of thin-walled channels, with good agreement found.