Experimental study of mechanical properties and failure mechanisms of metal-composite laminates reinforced with multi-walled carbon nanotubes

In this study, the tensile and flexural behavior of metal-nanocomposite laminates under tensile and flexural loading were experimentally investigated as well as their failure mechanisms. Flat laminates were made by hand lay-up of Aluminum face layers and a nanocomposite mid-layer including MWCNTs-reinforced polymeric matrix and glass fibers. Aluminum 1050 annealed sheets and 2D woven glass fibers with a surface density of 200 g/m2 were used. The nanocomposite layers contained 0, 0.5, 1, and 1.5 weight percentages of MWCNTs relative to the total weight of the polyvinyl chloride matrix. The effects of adding different amounts of MWCNTs on the mechanical properties of the laminates were evaluated. The results showed that both the tensile and flexural strengths of the reinforced specimens increase by adding up to 1 wt% of MWCNTs. The further addition of MWCNTs leads to aggregation and agglomeration of MWCNTs so that the tensile and flexural strengths are reduced to even less than those of the primary specimens. Moreover, a microscopic study of the fracture surfaces showed that the predominant failure mechanism in the tensile specimens is cohesive failure due to the fiber-matrix and Aluminum-composite debonding. The predominant failure mechanisms in bending tests are the destruction of the nanocomposite layer and metal-nanocomposite delamination.