A Method to Determine the Tangential Mechanical Properties of Pipes

Abstract

Pipe subjected to internal pressure has its highest mechanical stresses in the tangential direction. For a proper design of pipes, it is of paramount importance to relate the stresses to the right material properties. Currently there is no convenient standard test method to determine tangential pipe stress-strain behavior without flattening the pipe. Pipe flattening is found to alter the mechanical properties of a material. Very few researchers attempted to develop a method to determine pipes tangential properties. However, none of the proposed methods worked satisfactorily as they all had shortcomings. In this context, a novel testing and evaluation method for determining the tangential behavior of pipes is presented in this thesis. The testing method subjects a ring specimen, which is a ring cut from the pipeline, to load that mimics the internal pressure experienced in a pipe. The testing method ultimately aims to obtain the pipe's tangential true stress vs. strain behavior. A finite element model of the ring test is first built using ABAQUS to conduct an optimization study to determine the optimized ring specimen geometry and testing configuration. Aluminum pipes, Al 6063-T5, are used in this study, however the method is general and applicable to pipes of any other grades. An experimental investigation of the ring test was then conducted on Al 6063-T5 ring specimen following the optimized specimen geometry and configuration obtained from FEM. Friction present during the ring experimental test was found to alter the mechanical response of the material and mislead the actual material response. Evaluation methods of the results are thus presented to eliminate the friction alternation and ensure the correct mechanical response is obtained. Ultimately, the tangential true stress vs. strain curve of Al 6063-T5 pipe was obtained using the tangential testing method presented in this thesis.

Date of Award	Dec 2013
Original language	American English
Supervisor	IMAD Barsoum (Supervisor)