Effect of interfacial bonding upon compressive strength and fracture energy of carbon fiber reinforced polymer (CFRP) composite: A theoretical investigation

Under compression, polyacrylonitrile (PAN) based carbon fiber reinforced polymer (CFRP) composites fail by fiber microbuckling. The compressive strength of CFRP is known to be dependent upon the properties of the matrix and the fiber/matrix interfacial bond. Two-dimensional analytical models can not properly model interfacial stress distributions to address this relationship. An approximate three-dimensional micromechanics model for compressive behavior has therefore been developed and applied to carbon fiber/polysulfone and carbon fiber/polyetheretherketone (CF/PEEK) composites to predict the composite component responsible for initiating compressive failure, and the dependence of theoretical compressive strength and fracture energy upon interfacial bond strength. Results indicate that interfacial debonding or matrix shear yielding will occur well before fiber fracture and will thus be the initiator of fiber microbuckling instability, underscoring the importance of high interfacial bond strength and environmental resistance for the development of CFRP composite for structural orthopaedic implant applications. Design concepts for maximizing CFRP implant compressive strength and fracture energy are proposed.