An Experimental Investigation of Spall Fracture in Neat Epoxy and an Epoxy/Carbon Nanotube Composite

The spall strength of a material can be used to parameterize its ability to resist tensile failure under high-strain-rate loading. Dynamic failure in an assortment of representative materials was studied. A focus was placed on characterizing the mechanical properties of a polymer-matrix composite. Load frame testing was carried out to measure mechanical properties at quasi-static strain rates, while plate impact experiments were conducted to examine material response under dynamic loading conditions. Successful identification of the spall strengths and fracture toughnesses of aluminum 6061-T6 and polymethylmethacrylate (PMMA) validated the methods used in this investigation. An effect of the curing agent on the spall strength of an epoxy was identified. Nanotubes were found to have a detrimental effect on the dynamic mechanical properties of the resulting nanocomposite. Fracture surfaces of recovered nanocomposite fragments were imaged using a scanning electron microscope to identify failure mechanisms and propose a failure process.