Strona 2_redak - Instytut Agrofizyki im. Bohdana Dobrzańskiego ...

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Ghaboussi and Momen adopted the Drucker-Prager yield condition for a noncohesive
material (fig. 2.2):
2
F(σ
) = I − Y I
2
ij 2 1
=
0,
(2.17)
where Y is the yield constant, and the plastic potential of the same shape as the
yield condition additionally including isotropic and kinematic hardening:
G(
σij , αij,
κ)
= 0,
(2.18)
where:
α ij – kinematic hardening tensor,
κ – parameter of isotropic hardening.
The eight-parameter model of Ghaboussi and Momen contains 3 parameters descrybing
elasticity, 3 parameters of kinematic hardening, and 2 parameters of
isotropic hardening. The model describes correctly all phenomena typical for
isotropic as well as kinematic hardening, and it describes especially well the
anisotropy of the material, hysteresis in the load-unload cycle, and the evolution
of the hysteresis loop in the course of multiple loadings.
Fig. 2.2. A schematic of yield and plastic potential surfaces in the principal stresses space [175]