Scholarly Communications Project


Life Prediction of Composite Armor in an Unbonded Flexible Pipe

by

James S. Loverich

Master's Thesis submitted to the Faculty of the Virginia Tech in partial fulfillment of the requirements for the degree of

Master of Science

in

Engineering Mechanics

Approved

Kenneth L. Reifsnider, Chair
Michael W. Hyer
Scott L. Hendricks

April 29, 1997
Blacksburg, Virginia


Abstract

Composite materials are under consideration for the replacement of steel helical tendons in unbonded flexible pipes utilized by the offshore oil industry. Higher strength to weight ratios and increased corrosion resistance are the primary advantages of a composite material for this application. The current study focuses on the life prediction of a PPS/AS-4 carbon fiber composite proposed for the above employment. In order to accomplish this task, the properties of the material were experimentally characterized at varying temperatures, aging times and loadings. An analytic technique was developed to predict tensile rupture behavior from bend-compression rupture data. In comparison to tensile rupture tests, bend-compression rupture data collection are uncomplicated and efficient; thus, this technique effectively simplifies and accelerates the material characterization process. The service life model for the flexible pipe composite armor was constructed with MRLife, a well established performance simulation code for material systems developed by the Materials Response Group at Virginia Tech. In order to validate MRLife for the current material, experimental data are compared to life prediction results produced by the code. MRLife was then applied to predict the life of the flexible pipe composite armor in an ocean environment. This analysis takes into account the flexible pipe structure and the environmental and mechanical loading history of an ocean service location. Several parameter studies of a flexible pipe in a hypothetical environment were conducted. These analyses highlight certain loadings and conditions which are particularly detrimental to the life of the material.

Full text (PDF) 408,413 Bytes


The author grants to Virginia Tech or its agents the right to archive and display their thesis or dissertation in whole or in part in the University Libraries in all forms of media, now or hereafter known. The author retains all proprietary rights, such as patent rights. The author also retains the right to use in future works (such as articles or books) all or part of this thesis or dissertation.
[ETD main page] [Search ETDs][etd.vt.edu] [SCP home page] [library home page]

Send Suggestions or Comments to webmaster@scholar.lib.vt.edu