# Considerations concerning yield criteria insensitive to hydrostatic pressure

## Keywords:

plasticity, yield criteria, pressure insensitive, biaxial state of stress, invariants## Abstract

For distinguishing between pressure insensitive and pressure sensitive criteria, the form of yield surface with invariants is preferred. It is known that when this function can be formulated only in terms of the stress deviator invariants, it describes a pressure-insensitive material behaviour. But expression of criteria in terms of invariants may be a difficult goal in some particular cases. In the present paper is mathematically demonstrated that all criteria developed for standard plastic materials, in other words homogeneous, isotropic, ductile (without so-called strength differential or SD effect) materials, loaded in plane state of stress (2D space), are insensitive to hydrostatic pressure.

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