Abstract：This article used ANSYS to conduct simulation analysis of compact tension and 3 points bending test for the isotropic pyrolytic carbon and pyrolytic carboncoated graphite composite material used in heart valve prosthesis, calculated the plane strain fracture toughnessKIC and compared the calculated results with the results of related experiments, then analyzed the effectiveness of the method that used ANSYS to calculateKIC as well as the influence of the thickness ratio of the coating and substrate and crack tip radius for theKIC of pyrolytic carboncoated graphite composite material. Results showed that theKIC of the pure pyrolytic carbon and graphite material were respectively 1.176 MPa and 1415 MPa， which were close to the results of related experiments, verifying the accuracy of using ANSYS to calculateKIC; theKIC of composite material of pyrolytic carboncoated graphite reduced with the increase of thickness ratio for the coating and substrate. The fracture toughness of composite material was better than that of pure pyrolytic carbon or graphite composite material when the thickness ratio of coating and substrate was on the low side; pyrolitic carboncoated graphite had a limit notch root radiusρ0, which was about 5 μm, when the notch root radiusρ>ρ0, the measured value of KIC was proportional toρ1/2, and when ρ<ρ0, the measured value of KIC was in line with the value of samples with sharp crack.
