Thermal cycling and environmental effect on tensile impact behavior of single adhesive lap joints for fiber metal laminate

In this paper, the effects of sea water and thermal cycling conditions on adhesive lap joints made for fiber metal laminate (FML) and 430 stainless steel adherends are investigated. The FMLs are made by five alternative layers of three 430 stainless steel sheets and two prepreg glass fiber reinforced composite (G10) layers. The adherends are bonded by infusion of AD-314 resin mixed with HA-34 hardener. The joints are kept in the sea water taken from Persian Gulf for 30 days in the laboratory. Some of the specimens are then thermally cycled in an oven for 0, 5 and 10 cycles from 40 to 100 ◦C for the dwell time of 20 min and the others are kept in liquid nitrogen for 0, 5 and 10 cycles from -40 to -100 ◦C for the dwell time of 10 min, and afterwards tested in tensile impact loading according to standards. One specimen is also tested with 0 thermal cycling at ambient environment for comparison purpose. Experimental results revealed that the absorbed energy by adhesive lap joint specimens that are subjected to sea water is 37% of the same specimens tested at the ambient environment and the adhesive strength is improved by 30.7% and 40.6% for 5 and 10 thermal cycling at high temperature, but decreased by 14.85% for 5 and 10 thermal cycling at cryogenic temperatures with respect to sea water at 0 thermal cycling.