Elucidating the Mechanisms of Damage in Foam Core Sandwich Composites under Impact Loading and Low Temperatures.

Recent interest in Arctic exploration has brought new challenges concerning the mechanical behavior of lightweight materials for offshore structures. Exposure to seawater and cold temperatures are known to degrade the mechanical properties of several materials, thus, compromising the safety of personnel and structures. This study aims to investigate the low-velocity impact behavior of woven carbon/vinyl ester sandwich composites with PVC foam core at low temperatures for marine applications. The tests were performed in a drop tower impact system with an in-built environmental chamber. Impact responses, such as the contact force, displacement and absorbed energy, at four impact energies of 7.5 J, 15 J, 30 J, and 60 J were determined at four in-situ temperatures of 25 C, 0 C, -25 C and -50 C. Results showed that temperature has a significant influence on the dynamic impact behavior of sandwich composites. The sandwich composites were rendered stiff and brittle as the temperature decreased, which has a detrimental effect on their residual strength and durability. For example, at 60 J for all temperatures, the samples experienced perforation of the top facing and core, and the back facing exhibited varying extent of damage. At -25 C and -50 C, the sandwich composite samples were almost completely perforated. At all impact energies, the sandwich composites were rendered stiff and brittle as the temperature decreased, which has a detrimental effect on their residual strength and durability.