Adhesive tongue-and-groove joints for thick composite laminates

Abstract A new approach is explored for the joining of thick, woven E-glass/vinyl-ester composite laminated plates to steel or other composite plates, with applications in naval ship structures. Adhesive is applied along through-thickness contoured interfaces, employing tongue-and-groove geometry. Both experimental and finite element modeling results are presented. They show that adhesively bonded tongue-and-groove joints between steel and composite plates loaded in monotonically increasing longitudinal tension are stronger than conventional strap joints even in relatively thin plates. In particular, a single 0.25 inch wide and 8 or 12 inch long steel tongue, bonded by the Dexter-Hysol 9339 adhesive to a groove in a 0.5 inch thick laminated plate, can support a 20,000 lbs tension force. This force is expected to increase in proportion to plate thickness. Simple design rules indicate that the adhesive bond can be made stronger than that of the tongues, so that failure is transferred from the adhesive to the adherends. High joint efficiency can be achieved for any thickness of the joined plates.