Torque Limit of a Mechanical Fastener in a Graphite/Epoxy Joint

<p>Presently there is a lack of confidence amongst engineers when specifying the preload of a mechanical fastener in a composite joint due to a lack of a fundamental knowledge base regarding the behavior of composites under fastener compressive load. As such, a novel experimental procedure was developed herein to determine the through-the-thickness compressive (TTTC) material properties. A total of 206 property tests were performed on four different graphite/epoxy material systems. The results confirmed that TTTC material properties vary with fiber orientation, laminate thickness, fiber volume fraction, and even laminate surface finish. Hence, the 'rule of mixtures' provides a poor estimate of the TTTC modulus in that it fails to account for any of these variables.</p> <p>Finally, acoustic emission nondestructive testing, along with a modified approach to MSFC-STD-486B, Torque Limits for Standard Threaded Fastener, were used to determine the torque limit of a fastener in a single lap joint. The laminate configuration examined in these tests was manufactured in accordance with the MIL-HDBK-17 design code. The results demonstrated the inability of the fasteners employed to damage the one composite system investigated: fastener thread failure occurred first. Further study is necessary to confirm or refute these results for other composite systems and joint configurations.</p>

Name thesis:degree_name

Master of Science in Aerospace Engineering

Level thesis:degree_level

Thesis - Open Access

Discipline thesis:degree_discipline

Aerospace Engineering

Year

2002

Author dc:creator

• Kostreva, Kristian M.

Contributors dc:contributor

• Yi Zhao
• Eric v. K. Hill
• Frank J. Radosta

• torque
• mechanical fastener
• graphite/epoxy
• acoustic emission
• nondestructive testing
• Aerospace Engineering
• Structures and Materials

Repository record dc:identifier

https://commons.erau.edu/db-theses/105

OAI identifier oai:identifier

oai:commons.erau.edu:db-theses-1147