Adhesive Bond Strength of Bonded Structures in Confined Locations

Composite structures are the future of aviation. They reduce weight and improve fuel efficiency. Composite structures are now incorporated into aircraft by all major aerospace manufacturers. Many composite structures are assembled with fasteners, but, to meet future design requirements, manufacturers need adhesive bonding for their composite structures. In order for the industry to determine the safety and integrity and certify these aircraft, the adhesive bonds in these structures must be tested to verify the manufacturing process and, in subsequent depot level maintenance to confirm they are still adequate. There is no conventional non-destructive testing method available to assure that the bond strength is adequate for service. An inspection technology developed at LSP Technologies, Inc. offers a solution to evaluate the strength of adhesive bonds in bonded structures. This inspection technique is a local proof-testing method that applies a well-controlled dynamic tensile stress to the composite structure and senses inadequacies of these hard-to-detect weak adhesive bonds in response to the tensile stress. The tensile stress is generated by a pulsed laser beam interaction at the surface of the composite material. The controlled local stressing of the composite material has no effect on the material or properly bonded structures.