Influence of Incident Energy on Sisal/Epoxy Composite Subjected to Low Velocity Impact and Damage Characterization Using Ultrasonic C-Scan

Impact resistance is an inevitable characteristic of the composites employed in the high performance structural applications. Due to the growing interest in the use of sisal fibre as reinforcement in the polymer composites, it is required to determine the response of sisal/epoxy composites to low velocity impact at high incident energies where perforation can occur and assess the damage characteristics using a non-destructive technique. In this work, sisal/epoxy composites were subjected to drop weight impact in the velocity range of 3 m/s to 5 m/s at different energy levels between 20 J to 50 J according to the ASTM D7136. Based on the results observed, it is concluded that both the peak load and absorbed energy increased with the increasing incident energy level up to 40 J. At 50 J, perforation occurred and the maximum deformation was approximately 22 mm for the sisal/ epoxy composite. Damage characteristics and failure behaviour of the composite at different incident energies was examined from the visual images of the front and back face of the composite. The quantitative assessment of crack propagation in the sisal/epoxy composite and the damage area were determined from the ultrasonic C-scan images of the sample post impact at various energy levels.