High-temperature fracture properties of CFRP composite for aerospace applications

Long carbon fiber with 3.5 GPa in average tensile stress-reinforced heat-resistant epoxy composite has been studied to clarify high-temperature bending fracture behavior and mechanism of advanced carbon fiber reinforced plastic composite for aerospace applications. Unidirectional (0°/0° ply), cross-ply (0°/90° and +45°/−45° ply) and quasi-isotropic (0°/±45°/90° ply) laminates were used. Three-point slow bend tests were conducted over the temperature range of 293–503 K. The bending fracture stress of the 0°/0° ply laminates decreased with an increase in the temperature, while their bending fracture energies had little temperature dependence. For the 0°/90°, +45°/−45° and 0°/±45°/90° ply laminates, the bending fracture stress had little temperature dependence until it decreased suddenly at 503 K, whereas, their bending fracture energies increased with an increase in temperature. High-temperature bending fracture behavior of the composite laminates was characterized by the initiation and propagation of multiple failures of different modes, such as interfacial fracture, fiber breakage, shear fracture and delaminations between adjacent plies of the laminates.