Modeling of the mechanical behavior of HA/PEEK biocomposite under quasi-static tensile load

A cylindrical three-phase unit-cell model was established for predicting mechanical properties of hydroxyapatite (HA)-reinforced polyetheretherketone (PEEK) biocomposite. The model consists of an elastic–brittle HA spherical particle, an elasto-plastic matrix, and a very thin interphase region between the particle and the matrix. Perfect bonding was initially assumed among three phases before occurrence of particle–matrix debonding. For simulation of the particle–matrix debonding process of HA/PEEK, a damage evolution equation was incorporated into the material properties of the interphase region. A ductile damage evolution in the matrix was also taken into account, and was treated as a criterion for the failure of the biocomposite. A user subroutine for the damage-coupled material properties for the matrix and the interphase region was built and incorporated into a finite element code named ABAQUS. The influence of interfacial adhesion on the non-linear stress–strain relation of HA/PEEK has also been simulated by varying the tensile strength of the interphase region. The strength of the interphase region in the composite could be estimated by a comparison between the predicted and experimental results. By using the unit-cell modeling technique incorporated with the stress-based debonding and the composite failure criterion and selection of appropriate interphase strength, the numerical simulation was found to be close to the experimental results from available literatures. In vivo performance of HA/PEEK as implant materials was also discussed.