Experimental investigation of charpy impact in energy absorption of hybrid and non-hybrid sandwich structures reinforced with carbon nanofiber

This paper aims to identify damage mechanism and the amount of energy absorption of sandwich composites under the Charpy impact test. Each of the samples are made of a core with PVC foam and faces with different materials consisting of innegra, carbon, and hybrid innegra/carbon. All the faces comprises of 4 layers reinforced with modified epoxy resin by carbon nanofiber (CNF) which are located on the top and the bottom of the core. CNFs are added to the epoxy resin with a weight ratio varying from 0 to 0.5 percent. The samples were prepared based on ASTM D256 standards and then loaded. After the Charpy impact test, the samples were photographed to evaluate the induced damage severity. The results showed all samples reinforced with CNF have higher energy absorption than the virgin ones. The increase in energy absorption of CNF added innegra sandwich composites is significant in comparison to the other samples where the innegra sandwich composite with 0.5 percent CNF shows the highest energy absorption. This was not same for the other samples and CNF adding didn’t affect energy absorption considerably. Comparing the induced damage mechanism showed that delamination was intensive for the hybrid samples, showing that innegra and carbon are not an appropriate combination to stand impact loading