Shape Of Crack Tip Plastic Zone Research Articles

Crack tip plastic zone shape for anisotropic material subjected to mode -I loading

This paper discusses the effect of anisotropy in terms of anisotropy ratio on ductile materials subjected to mode-I type of loading. Thin plate with plane stress condition is considered for this work. σ3 is taken as zero. For considering the effect of Poisson’s ratio, σ3 = ν (σ1 + σ2) is considered. Isotropic plane strain and anisotropic plane stress condition is considered to develop mathematical relations for stress triaxiality and plastic zone around the crack tip by using Hill – von Mises’s yield criterion. The effect of poisons ratio, anisotropy ratio and stress triaxiality is shown on the size of plastic zone around the crack tip. The results were generated and are compared in the form of polar plot for plane strain condition at different Poisson’s ratio. In addition to this, the effect of anisotropy ratio on stress triaxiality is also investigated. It was observed that increase in Poisson’s ratio causes significant reduction in the size of plastic zone around the crack tip. The increase in anisotropy ratio also shows the same trend, especially for its higher values. It is observed that anisotropy plane stress problem of fracture is almost equivalent to isotropic fracture in plane strain condition.

The Effect of Stress State Characteristics on the Surface Fatigue Cracks Growth Rate Taking into Account Plastic Deformations

The technique of fatigue tests of steel cross-shaped samples with a surface crack under biaxial loading is described. The sample and equipment for the implementation a biaxial tension and compression-tension in a working part of the sample are proposed. The sample and equipment for the implementation a biaxial tension and compression-tension in a working part of the sample are offered. Test results of structural steel 20 samples are presented. A stress effect parallel to a crack plane on its growth rate is determined. Crack tip plastic zone shape and sizes under various loading conditions are studied. The relationship of a fatigue crack growth rate and a plastic deformation area size is established. The formula to determine the growth rate of a surface crack under biaxial loading taking into account a plastic deformation is proposed.

3D finite element analysis on crack-tip plastic zone

This paper presents an effect of specimen thickness on crack-tip plastic zone shape and size. The shape of the plastic zone is estimated in 3D with the help of elastic and elastic-plastic finite element analyses. The results indicate that the shape of plastic zone does not correspond to classical “dog-bone shape” and the maximum plastic zone size occurs beneath the free surface, contrary to conventional shape. It is observed that for specimens with B/W=0.5, the ASTM requirement of specimen thickness to estimate KIC, the plastic zone shape and size is much larger than the one obtained in 2D plane strain analysis. The results also show a significant change in the shape and size of plastic zone in elastic and elastic plastic conditions. International Journal of Engineering, Science and Technology, Vol. 2, No. 6, 2010, pp. 47-58

Analytical Solutions for Crack Tip Plastic Zone Shape Using the Von Mises and Tresca Yield Criteria: Effects of Crack Mode and Stress Condition

AbstractAnalytical closed-form solutions for the crack tip plastic zone shape have been derived for a semi-infinite crack in an isotropic elastic-perfectly plastic solid under both plane stress and plane strain conditions. Two yield criteria have been applied: the Von Mises and Tresca yield criteria. The solutions have been developed for crack modes I and III (mode II has been published previously). The results, which favorably compare to a limited number of existing experimental and analytical findings, indicate that the Tresca zone is larger in size than the Von Mises zone. Moreover, an interesting observation is that both zones are generally much larger than the ones predicted by classical Irwin and Dugdale-Barenblatt solutions.

Closed-Form Solutions for the Mode ii Crack tip Plastic Zone Shape

Analytical closed-form solutions for the Mode II crack tip plastic zone shape have been derived for a semi-infinite crack in an isotropic elastic-plastic solid under both plane stress and plane strain conditions. Two yield criteria have been applied: the Von Mises and Tresca yield criteria. The results indicate that the Tresca zone is larger in size than the Von Mises zone. The results also reveal an intricate dependence on Poisson's ratio in plane strain conditions.

A Study of Crack Tip Plastic Zone Topography in Beryllium

Abstract Multiple-beam interferometry has been used to study the size and shape of plastic zones both at the tip of subcritical cracks and at the edges of running cracks in rolled ingot and in hot pressed, fully dense and porous beryllium. It is shown that from the zone shape an effective yield stress for the material can be derived and that this stress corresponds to somewhere between the 0.2% proof stress and the microyield stress of the material as measured under uniaxial tension. The relevance of this effective yield stress to practical fracture toughness testing is discussed and it is shown that from the points of view of both overall crack tip plastic zone shape and of the effects of plasticity on elastic stress redistribution, the 0.2% proof stress is probably the best choice.