engleski

Smooth Yield Surfaces of Isotropic Materials

Two types of the tensor formulation of the general yield criteria are presented. The first one having an invariant form describes smooth yield surfaces such as the von Mises circular cylinder. The second type defines multiple yield surfaces and it is convenient for the description of a smooth prism, i.e. Tresca’s hexagonal prism. Only the first invariant form has been investigated. In the case of a general isotropic material having different tensile and compressive yield strengths, three independent material constants have to be measured in order to achieve a complete description of the yield surface. Usually, these constants are tensile yield strength SY.t, compressive yield strength SY.c, and shearing yield strength TY. Furthermore, it has been shown that the first stress invariant Skk directly influences yielding. If an isotropic material exhibits equal tensile and compressive yield strengths, then Skk does not influence yielding. In that case only one material constant, usually SY.t, suffices for the description of the yield surface.

yield surface; smooth; yield strength; tensor formulation

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