Mechanics of fatigue damage in titanium-graphite hybrid laminates

Titanium-graphite hybrid laminates are being developed for high-temperature aerospace applications. Experimental observations have indicated that cracks in the titanium facesheets initiate at free edges as well as in areas of high stress concentration, such as holes and notches and that a delaminated region between the facesheet and the intact plies develops and propagates in the wake of the facesheet crack. This thesis experimentally and analytically evaluates the facesheet crack and delamination growth behavior of TiGr laminates. The delamination growth behavior is studied by isolating delamination growth using TiGr specimens with facesheet seams. The growth rate of delamination from facesheet seams is related via a power law to the applied strain energy release rate. It is shown that elevated temperatures significantly increase the growth rate of facesheet delamination. The facesheet crack growth behavior in TiGr laminates was measured experimentally and compared to model predictions. It is shown that the crack growth rate in TiGr facesheets is significantly lower for TiGr laminates as compared to monolithic titanium. After an initial decrease in crack growth rate, the crack propagates at a constant rate while the crack growth rate for monolithic titanium increases as the crack extends.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Aeronautics and Astronautics.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2001

Author dc:creator

• Burianek, Dennis Arthur

Advisor dc:contributor.advisor

• S. Mark Spearing.

• Aeronautics and Astronautics.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/8704

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/8704