Artificial heart valve pyrolytic carbon and testing method for fracture toughness of pyrolytic carbon composite material

Abstract

The invention relates to an artificial heart valve pyrolytic carbon and a testing method for the fracture toughness of a pyrolytic carbon composite material. A testing method for the fracture toughness of the pyrolytic carbon composite material has not been brought forward yet. The testing method provided by the invention comprises the following steps: preparing a plurality of compact tension C(T) specimens from heart valve pyrolytic carbon or a composite material thereof and prefabricating sharp cracks on each specimen, wherein the specimen is of a specification as recommended by American ASTM standard E399, a gap is processed at the central part of the specimen, and upper and lower ends of the gap are respectively provided with a loading hole; then respectively clamping the two loading holes of the gap by using clamps and erecting an extensometer on an open end of the gap; and starting a loading platform to apply an upward load increasing at a uniform speed until the specimens fracture, determining critical load and effective crack length of each specimen, calculating fracture toughness according to the critical load and the effective crack length and taking a mean value as a fracture toughness test value of the heart valve pyrolytic carbon or the composite material thereof. The method provided by the invention can accurately determine fracture toughness of pure pyrolytic carbon and a pyrolytic carbon composite material.

Description

technical field [0001] The invention relates to a method for testing the mechanical properties of carbon materials, in particular to a method for testing the fracture toughness of artificial heart valve pyrolytic carbon and composite materials thereof. Background technique [0002] The artificial heart valve is a substitute for the human heart valve, which is used for the replacement of patients with heart valve disease. The valve is often made of pure pyrolytic carbon or pyrolytic carbon coated graphite composite material, and the valve ring is often made of pure pyrolytic carbon or titanium alloy. production. The artificial heart valve has been operating in the complex physiological environment of the human body for decades, and requires high durability and structural reliability. Therefore, the pyrolytic carbon material used as its surface coating needs to have good fracture performance. [0003] Plane strain fracture toughness is an important parameter for the fracture ...

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Problems solved by technology

Due to the particularity of its preparation process, the sample size is small and the thickness is thin, many traditional fracture toughness test methods are not applicable to it. Therefore, there is no such report in China on the fracture toughness test of pyrolytic carbon for artificial heart valves.

Foreign Ritchie, Cao Hengchu, Glipin and others have conducted some research on the fracture toughness of artificial heart valve pyrolytic carbon, but did not propose a set of test methods for the fracture toughness of artificial heart valve pyrolytic carbon

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