Plane strain crack problems for elastic materials with variable properties

Plane-strain crack-tip stress and strain fields are presented for materials exhibiting pressure-sensitive yielding and plastic volumetric deformation. The yield criterion is described by a linear combination of the effective stress and the hydrostatic stress, and the plastic dilatancy is introduced by the normality flow rule. The material hardening is assumed to follow a power-law relation. For small pressure sensitivity, the plane-strain mode I singular fields are found in a separable form similar to the HRR fields (Hutchinson, 1968a, b; Rice and Rosengren, 1968). The angular distributions of the fields depend on the material-hardening exponent and the pressure-sensitivity parameter. The low-hardening solutions for different degrees of pressure sensitivity are found to agree remarkably with the corresponding perfectly-plastic solutions. An important aspect of the effects of pressure-sensitive yielding and plastic dilatancy on the crack-tip fields is the lowering of the hydrostatic stress and the effective stress directly ahead of the crack tip, which may contribute to the experimentally-observed enhancement of fracture toughness in some ceramic and polymeric composite materials.

Download Full-text

The equilibrium field near the tip of a crack for finite plane strain of incompressible elastic materials

Journal of Elasticity ◽

10.1007/bf00043706 ◽

1982 ◽

Vol 12 (1) ◽

pp. 65-99 ◽

Cited By ~ 68

Author(s):

Rodney A. Stephenson

Keyword(s):

Plane Strain ◽

Finite Plane ◽

Elastic Materials

Download Full-text

Virtual Methods in Creep Crack Growth Predictions in 316H Stainless Steels

Volume 9: Eighth International Conference on Creep and Fatigue at Elevated Temperatures ◽

10.1115/creep2007-26446 ◽

2007 ◽

Cited By ~ 1

Author(s):

Masataka Yatomi ◽

Kamran M. Nikbin

Keyword(s):

Crack Growth ◽

Plane Strain ◽

Stainless Steels ◽

Creep Crack Growth ◽

Crack Propagation Rate ◽

Creep Model ◽

Elastic Plastic ◽

Creep Crack ◽

Plastic Creep ◽

Plane Strain Crack

The paper discusses numerically based virtual techniques of creep crack growth predictions in a fracture mechanics component. The material properties used are for 316H stainless steels and the constitutive behaviour of the steel is described by a power law creep model. A damage-based approach is used to predict the crack propagation rate in compact tension (C(T)) specimens and the data are correlated against an independently determined C* parameter. Elastic-plastic-creep analyses are performed using two different crack growth criteria to predict crack extension under plane stress and plane strain conditions. The NSW and NSW-MOD strain exhaustion models are applied to compare to the experimental data and FE predictions. The plane strain crack growth rate predicted from the numerical analysis is found to be less conservative than the plane strain NSW model but more conservative than plane strain NSW-MOD model, for values of C* within the limits of the present creep crack growth testing standards. At higher loads and C* values, the plane strain crack growth rates, predicted using an elastic-plastic-creep material response, approach is considered and compared to the plane strain NSW-MOD model.

Download Full-text