Mechanism of Plastic Flow of Gaskets and Anvils in 6-8 Type Anvils
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In the 6-8 type anvils, the occurrences of blow-out have restricted the attainable pressure to 25 GPa. The cause of blow-out was attributed to the fracture of the cube of the second stage anvils maade made of cemented tungsten carbide (WC). The stress state in the cube was, therefore, calculated by a finite element method. As a result, there was a fracture line in the stress diagram of σ<SUB>0</SUB> vs σ<SUB>m</SUB> that was expressed as σ<SUB>0</SUB>=S<SUB>0</SUB>- (3/2) σ<SUB>m</SUB>, where σ<SUB>0</SUB>, σ<SUB>m</SUB>, and S<SUB>0</SUB> were the equivalent stress of von Mises, the mean normal stress, and half of the compressible strength, respectively. Furthermore, the breakage of pyrophyllite was also proven to follow the same fracture line except for the value of S<SUB>0</SUB>. In Bridgman, anvils the expression of failure stress which derived from our flow model on the basis of the fracture line, accounted for the compressible strength of the various thicknesses of gaskets. The observed plastic deformation of the cube of the second stage anvils would already occur at lower pressures when the σ<SUB>0</SUB> exceeded the parallel fracture line, where the S<SUB>0</SUB> was less than the value at failure.
- The Review of High Pressure Science and Technology
The Review of High Pressure Science and Technology 7, 1514-1516, 1998
The Japan Society of High Pressure Science and Technology