Analytical and Numerical Study of the Ring Expansion Testing Technique

Abstract

Abstract This article presents a design development for the ring expansion test as an alternative technique of burst test to determine the mechanical properties of circular homogeneous thin-walled tubes in the hoop direction where it is supposed to fail. This is done by replacing the internal fluid pressure in burst test by a solid mandrel partitioned into an equal number of pieces. The numerical analyses were carried out using the commercial finite element method (FEM) package ABAQUS/CAE. The testing system consists of a multispecies mandrel assembled with two identical cones from top and bottom, and the ring specimen circumscribes the mandrel, which expands radially as a result of the cone’s axial displacement. The FEM was used to optimize the proposed design in terms of the minimum number of pieces in use. In addition, the effects of friction between the cones/the mandrel and between the ring/the mandrel are investigated. The FEM revealed that eight mandrel pieces or more are needed to preserve a uniform hoop stress throughout the ring circumference. Moreover, the FEM results in conjunction with theoretical formulas revealed that eight mandrel pieces at a minimum are required to minimize the power dissipated because of friction to a nuance value of 2 %. It is concluded that the higher the number of pieces used, the more uniform the hoop stress generated in the ring specimen. Moreover, it can effectively decrease friction effect at the ring/mandrel interface. The FEM also makes a great contribution in estimating the friction coefficients as it is restricted to be evaluated experimentally.