Low Velocity Impact Response of Bio-inspired Fiberglass Woven Composites

Abstract

For many years, nature has provided some of the most effective solutions to challenging problems that men have faced. Scientists and researchers have tried to mimic natures approach in order to improve and advance human`s life. In this study, the multistate structure of turtle shell is used to improve the impact resistance of out of autoclaved polymeric composite laminate. The optimally designed turtle shell possesses three layers: The exterior and interior which made out of cortical bone and the middle layer which consists of cancerous bone. This interesting structure provides high stiffness on the outside, especially under out if plane loadings while giving a possibility of small elastic deformations on the inner side. The shell comprises of a multiphase sandwich composite structure of functionally graded material having exterior bone layers and a foam-like bony network of closed-cells between the two exterior bone layers. This concept is used in designing an out of autoclaved woven composite in order to minimize the deformation and damage in the composite when subjected to low velocity impact loading. The progressive deformation and damage behavior of composite panels with polymer membrane impacted by drop-weights at four different velocities were investigated. The specimens tested were made of woven fiberglass fabric/ toughened epoxy (cured at 1200 C). During these low-velocity impact tests, the time-histories of impact-induced dynamic strains and impact forces were recorded. The damaged specimens were inspected visually. Test results revealed that the polymer membrane layer plays a significant role on the overall deformation and damage behavior of the composites under impact loading. These findings could provide fundamental understanding of structure-property phenomena and biological pathways to design efficient energy absorbing bio-inspired composite materials for various composite structures which are susceptible to the impact damage.