An experimental investigation of fracture modes and delamination behavior of carbon fiber reinforced laminated composite materials

Mechanically, composite laminates perform exceptionally well in-plane but poorly out-of-plane. Interlaminar damage, known as "delamination," is a major issue for composite laminates. Results from Mode-I and Mode-II experimental testing on twill-woven carbon fiber reinforced (CFRP) laminates are analyzed in this paper. Composite Mode-I fracture toughness was determined using three different methods in accordance with ASTM D5528: modified beam theory, compliance calibration, and a codified compliance calibration. Two methods, the Compliance Calibration Method and the Compliance-Based Beam Method, were used to determine the Mode-II fracture toughness in accordance with ASTM D7905. Stick-slip behavior is quite evident in the composite's Mode-I fracture toughness test findings. The MBT technique's GIc values for initiation and propagation are 0.533 and 0.679 KJ/m2, respectively. When comparing the MBT approach to the industry-standard ASTM procedure for determining fracture toughness Mode-I, the MBT method was shown to be highly compatible. Furthermore, the GIIc values for the CBBM technique are 1.65 KJ/m2 for non-pre cracked and 1.4 KJ/m2 for pre-cracked materials. The CBBM method shows a good method to evaluate fracture toughness Mode-II, due to not needing to monitor the length of the crack during delamination growth to get the value of the fracture toughness.