The Distortion and Buckling of Long Viscoelastic Cylinders in Pure Bending

Abstract

The behaviour in pure bending of moderately thick polypropylene cylinders is examined. The distortion into an oval cross-section is measured as the bulging and flattening displacements. The bending radius at buckling is also determined.

When compared with an existing theory for thin-walled Hookean cylinders both the distortion and buckling are found to be functions of a single reduced parameter involving the tube dimensions and the bending curvature, as predicted. However, the amount of distortion and the buckling radius are both less than the theoretical values. These discrepancies are explained by the mechanical nonlinearity of polypropylene.