الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 124 |  |  |
| | | from | 124 | | |
Abstract
This thesis shows a design development for the ring expansion test as an alternative method to the burst test to evaluate the mechanical properties of round homogeneous thin-walled cylinders in the hoop direction where it is expected to fail. This is carried out by replacing the internal fluid pressure in the burst test with a solid mandrel split into an equal number of pieces. The finite element analyses were done using the commercial finite element method (FEM) package ABAQUS/CAE while the experimental work was done using a universal testing machine. The testing system consists of a multi-piece mandrel assembled with two identical cones from top and bottom, and the ring specimen surrounds the mandrel, which expands in the radial direction because of the cone’s axial displacement (due to the wedge effect). 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 were studied. The FEM revealed that eight mandrel pieces or more are needed to maintain uniform hoop stress along the ring circumference. Moreover, the FEM results in conjunction with theoretical equations revealed that eight mandrel pieces at a minimum are required to minimize the pressure dissipated due to 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. Additionally, it can effectively decrease the 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. The experimental work aimed to compare the stress-strain behavior of the conventional tensile test with the proposed design and it showed similarities in terms of modulus of toughness and yield strength.