Investigating the mechanical performance of advanced marine coatings used for bonding composites to aluminum in-mold

Advanced Marine Coatings (AMCs) are a combination of polyurethane technology with polyester technology. In this study, AMCs' various formulations were tested for mechanical properties and lap shear strength between composite laminates and aluminum. Castings were fabricated for each formulation, and their mechanical properties were obtained through ASTM Testing. The lap shear strength between composite laminates and aluminum was determined by single lap shear testing. Numerical models were created to simulate the experimental lap joint testing and further analyze the adhesive at the joint using the mechanical properties obtained in this study. The numerical model was used to produce peel strain and shear strain contour plots of the adhesive and peel stress and shear stress distributions at the mid-layer of the adhesive at 85% failure load. The effects of changing the ratio of the polyurethane components on the AMC's performance were also investigated. With the exception of failure shear strain, the mechanical properties were found to be inversely proportional to the amount of polyurethane added to the formulation. However, increasing the ratio of isocyanate to polyol increased the formulation's mechanical properties at each formulation's specified polyurethane percentage.