Fracture toughness of fiber metal laminates: Carbon nanotube modified Ti-polymer-matrix composite interface

Multifunctional hybrid composites are proposed as novel solutions to meet the demands in various industrial applications ranging from aerospace to biomedicine. The combination of carbon fiber and/or fabric, metal foil, and carbon nanotubes is utilized to develop such composites. This study focuses on processing and fracture toughness characterization of the carbon fiber-reinforced polymer–matrix composites and the carbon nanotube modified interface between the polymer–matrix composite and titanium foil. Vacuum Assisted Resin Transfer Molding (VARTM) process is used to fabricate the laminate. Double cantilever beam tests at both room temperature and high temperature are conducted to assess the mode I interlaminar fracture toughness. The experimental and characterization efforts suggest that carbon nanotubes improve bonding at the hybrid interface. Simple computational models are developed to assist the interpretation of experimental results and further investigate the damage modes. The numerical results agree well with the limited experiments at crack initiation and furthermore support the absence of mode mixity.