Effect of Cyclic Corrosion on Static Strength of Composite/Aluminum Double Lap Joints

This study investigates effect of cyclic corrosion on the static strength of double lap joints (DLJs) that are either bonded-only, bolted-only, or hybrid bonded-and- bolted. Carbon-Fiber-Reinforced thermoplastic composite material is bonded to Aluminum Alloy 6060 using either polyurethane-based or epoxy-based structural adhesives. Bolting is achieved using an M4-0.7 Class 8.8 threaded fasteners that are properly preloaded. Treatment of bonded surfaces include abrasion blasting, followed by ultrasonic solvent cleaning and roughness measurement using Wyko optical profilometer. Assembled DLJs are placed in a cyclic corrosion (salt-fog) test chamber following standard GMW 14872 3-stage cyclic corrosion test. Joints are pulled out for tensile-shear testing and visual inspection after 1, 7, 14, 22, and 30 days of exposure to cyclic corrosion. Results, discussion, observations, and conclusions are provided.