On the Response of Elastic-Plastic Tubes Under Combined Bending and Tension

This paper is concerned with the response of long, relatively thin-walled tubes bent into the plastic range in the presence of axial tension. The work is motivated by the design needs of pipelines installed and operated in deep offshore waters. The problem is studied through a combination of experiment and analysis. In the experiments, long metal tubes were bent over a smooth, circular, rigid surface (mandrel). Bending of the tubes was achieved by shear and axial end loads. The experimental arrangement is such that a significant section of the test specimen is loaded and deformed in an axially uniform fashion. The ovalization induced in the specimen was measured as a function of the axial load in the tube for two mandrel radii. A two-dimensional numerical simulation of the problem has been developed and validated against the experimental results. This analysis was used to conduct a parametric study of the effect of tension on the ovalization induced in a long tube during bending.