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Tensile Strength of an Interlocking Composite Connection



Dat Duthinh


Twenty-four tests of an interlocking fiber-reinforced polymer (FRP) connection show that, although the connection is much weaker than the theoretical strength of the panel under the same type of load (in-plane tension transverse to the main reinforcement direction), it is well designed and performs its function satisfactorily. The tensile strength of the connection exhibits a fair amount of variability, even under controlled conditions, except for the interlocked, no bond configuration. Adhesive bonding adds significantly to the strength of this interlocking joint. Spreading adhesive on both mating faces in the absence of an interlocking toggle produces a more complete bond area and a thicker bond line, resulting in significantly higher connection strength than if the adhesive is deposited on only one face and a toggle is used. Infills of various stiffness has no effect on strength and the toggle shows no sign of damage at connection failure.
NIST Interagency/Internal Report (NISTIR) - 6565
Report Number


adhesive, bond, composite, connection, fiber-reinforced polymer (FRP), interlocking, joint, panel, tensile strength


Duthinh, D. (2000), Tensile Strength of an Interlocking Composite Connection, NIST Interagency/Internal Report (NISTIR), National Institute of Standards and Technology, Gaithersburg, MD (Accessed May 22, 2024)


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Created October 1, 2000, Updated February 19, 2017