Functionally Graded Adhesive Patch Repairs of Wood Beams in Civil Applications
Publication: Journal of Composites for Construction
Volume 19, Issue 2
Abstract
Several investigations have been made concerning the fracture behavior of scaled specimens of wood beams repaired with adhesively bonded carbon fiber reinforced polymer (CFRP). However, one of the problems associated to these joints is the fact that the stress distribution (shear and peel) is concentrated at the ends of the overlap, leading to premature failure of the joint. The stress concentration can be reduced with use of a functionally graded adhesive, in which the mechanical properties vary along the bond length. This can be achieved with a graded cure, in which the temperature varies along the bond length. In this study, the repair of wood structures with CFRP was made using a homogeneous cure and a graded cure. The graded cure was performed by induction heating. This technique has already been successfully tested in single lap joints to increase the strength of the joint. Two common types of defects on beams under bending loads were analyzed (compression and cross grain tension damage). Scaled specimens of damaged wood beams were repaired and tested under four point bending. The results show that the cross grain tension beams repaired with a graded bondline were able to withstand higher loads than the beams repaired with a homogeneous bondline. This failure load of the graded repaired beam increases with an increase of the overlap length.
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Acknowledgments
The authors gratefully acknowledge the funding by the Portuguese Science and Technology Foundation under the project PTDC / EME-PME / 098571 / 2008 and Henkel Iberia for supplying adhesive Loctite Hysol 3422.
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Published In
Journal of Composites for Construction
Volume 19 • Issue 2 • April 2015
Copyright
© 2014 American Society of Civil Engineers.
History
Received: Dec 2, 2013
Accepted: May 12, 2014
Published online: Jul 2, 2014
Discussion open until: Dec 2, 2014
Published in print: Apr 1, 2015
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