Bilayer AA7075-thermoplastic composite structures manufactured by hot pressing: Effect of glass fiber amount of polypropylene composite on mechanical properties

This article presents a research into the development of novel Hybrid Laminates (HLs) prepared with the use of hot-pressing method. Two types of HLs are fabricated through the composite coating with different fiber amounts (40 and 50% wt.) of only one surface of 7075-O Al alloy substrate. Effects of the fiber contents of the thermoplastic composite in the hybrid structures are investigated with regards to the tensile and flexural properties. The influence of bending load applied from different surfaces on flexural responses is also evaluated. The tensile test results indicate that the increased fiber ratio slightly affects the failure load of composite layer in the HLs. On the other hand, the flexural strength decreases with the increasing fiber amount in the HLs whether the three-point bending is performed on the Al surface or the composite layer. Scanning electron microscopy (SEM) is used to study the fracture surfaces after the mechanical characterization. From the SEM observations, it has been realized that fiber/matrix debonding is the key failure mechanism during the tensile tests. The failure mode of both HLs is delamination in the PP composite at the tensile side when the bending applied from the Al layer.