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Heat-Induced Disbonding and Degradation of Adhesive Bonds in Honeycomb Sandwich Structures

The development of nondestructive testing (NDT) techniques for detecting and characterizing disbonds in honeycomb sandwich structures is often hampered by the lack of test articles that contain known discontinuities. This paper describes a method for producing controlled, realistic and often nearly invisible disbonds on actual honeycomb sandwich components. The method uses localized heating on the facesheet to create disbonds from the honeycomb core in a variety of metallic and composite sandwich structures removed from an aircraft. In addition, heat cycling to a temperature below that which causes disbonding is used as a way to degrade the bond strength to different degrees. Heat-induced disbonding and degradation on a slat wedge are detected and imaged by a number of NDT techniques in a round-robin test.

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