Role of Interfacial Strength on Toughness of Three-layer Aluminum Composite Laminates under Dynamic Loading

Lamination has been shown to enhance damage tolerance of discontinuously reinforced aluminum (DRA) composites. Doing this technique, usually DRA layers are laminated with ductile interlayers. In this research, laminates consisting two Al6061-5 vol.%SiCP (DRA) layers and one ductile Al1050 interlayer were made by means of hot roll bonding. Different number of rolling passes, i.e. different rolling strains, was applied to control the interfacial strength. Shear test results revealed that the interfacial strength of laminates increase by the number of rolling passes. Fracture behavior of laminates was evaluated under dynamic loading on specimens with the crack divider morphology. Results of this study illustrate that while the impact toughness of DRA is improved significantly by lamination, improvement of the interfacial strength deteriorates the energy absorption of the laminate. Based on optical and scanning electron microscopy studies, it is postulated that interfacial delamination and plastic deformation of the ductile interlayer are the two major energy absorption mechanisms in these laminates. This is why the laminate comprising the least interfacial strength provides the maximum toughness.