Fatigue testing of composite patches for ship plating fracture repair

ABSTRACT

The objective of this study is to examine, through physical testing, the use of composite patches for preventing crack growth and extending the service life of ship plating. Fatigue tests were conducted on steel plates to experimentally validate the effectiveness of using composite patches as a means to prevent crack growth and extend the fatigue life of structural components. Specimens were tested with and without the use of composite reinforcements. Previous results of numerical analysis studies had indicated that a one- to two-order of magnitude increase in service life can be expected for the conditions tested. The experimental results presented here show increases closer to a single order of magnitude. The difference is attributed to two factors: failure mechanisms associated with debonding of the patch and cracking of the patch itself. Of critical importance, therefore, are the implementation of a quality-controlled bonding procedure and optimisation of the geometry and properties of the patch systems based upon the parent plate's properties and fracture conditions.

KEYWORDS:

• Crack propagation
• composite patching
• fatigue life

Acknowledgments

The research, experimentation, and testing was made possible by the Ship Structure Committee support awarded through the Naval Surface Warfare Center, Carderock Division and through BMT Designers and Planners. A total of 11 engineers and technical representatives at the U.S. Coast Guard, the U.S. Navy, and the ABS contributed information to this study. Their willingness to share their expertise in this area is greatly appreciated. The contributions of Robert Spence and Robert Fischer to the testing of the steel plate specimens in the Structural Engineering Laboratory at the University of Michigan are also greatly appreciated.

Disclosure statement

No potential conflict of interest was reported by the authors.