A novel system for self-validating adhesive joints

A self-validating adhesive system is proposed in which `zero volume unbonds’ or `kissing’ bonds, which are undetectable by NDE techniques, may be filled and bonded by a secondary component in the adhesive during cure. The system shows the principal criteria required for such a smart system, and has been shown to enhance the strength of a bonded joint without undue deterioration in durability or water uptake.