scholarly journals Plane-stress crack-tip fields for power-law hardening orthotropic materials

1988 ◽  
Vol 37 (3) ◽  
pp. 171-195 ◽  
Author(s):  
Jwo Pan ◽  
C. Fong Shih
Keyword(s):  
Power Law ◽  
Plane Stress ◽  
Crack Tip ◽  
Orthotropic Materials ◽  
Crack Tip Fields

On Higher-Order Crack-Tip Fields in Creeping Solids

1999 ◽  
Vol 67 (2) ◽  
pp. 372-382 ◽  
Author(s):  
B. N. Nguyen ◽  
P. R. Onck ◽  
E. van der Giessen
Keyword(s):  
Power Law ◽  
Crack Tip ◽  
Small Strain ◽  
Higher Order ◽  
Single Edge ◽  
Constraint Effect ◽  
Scaling Properties ◽  
Crack Tip Fields ◽  
Asymptotic Development ◽  
Loading Parameter

In view of the near-tip constraint effect imposed by the geometry and loading configuration, a creep fracture analysis based on C* only is generally not sufficient. This paper presents a formulation of higher-order crack-tip fields in steady power-law creeping solids which can be derived from an asymptotic development of near-tip fields analogous to that of Sharma and Aravas and Yang et al. for elastoplastic bodies. The higher-order fields are controlled by a parameter named A2*, similar as in elastoplasticity, and a second loading parameter, σ∞. By means of the scaling properties for power-law materials, it is shown that A2* for a flat test specimen is independent of the loading level. Finally, we carry out small-strain finite element analyses of creep in single-edge notched tension, centered crack panel under tension, and single-edge notched bending specimens in order to determine the corresponding values of A2* for mode I cracks under plane-strain conditions. [S0021-8936(00)01202-2]

Elastic-plastic J-Tz dominance in bending and tension loadings

2019 ◽  
Vol 10 (5) ◽  
pp. 644-659
Author(s):  
Feizal Yusof ◽  
Karh Heng Leong
Keyword(s):  
Crack Length ◽  
Power Law ◽  
Crack Front ◽  
Three Dimensional ◽  
Crack Tip ◽  
Content Type ◽  
Elastic Plastic ◽  
Crack Tip Fields ◽  
Out Of Plane ◽  
Crack Tip Stress

Purpose Crack tip stresses are used to relate the ability of structures to perform under the influence of cracks and defects. One of the methods to determine three-dimensional crack tip stresses is through the J-Tz method. The J-Tz method has been used extensively to characterize the stresses of cracked geometries that demonstrate positive T-stress but limited in characterizing negative T-stresses. The purpose of this paper is to apply the J-Tz method to characterize a three-dimensional crack tip stress field in a changing crack length from positive to negative T-stress geometries. Design/methodology/approach Elastic-plastic crack border fields of deep and shallow cracks in tension and bending loads were investigated through a series of three-dimensional finite element (FE) and analytical J-Tz solutions for a range of crack lengths ranging from 0.1⩽a/W⩽0.5 for two thickness extremes of B/(W − a)=1 and 0.05. Findings Both the FE and the J-Tz approaches showed that the combined in-plane and the out-of-plane constraint loss were differently affected by the T-stress and the out-of-plane size effects when the crack length changed from deep to shallow cracks. The conditions of the J-Tz dominance on the three-dimensional crack front tip were shown to be limited to positive T-stress geometries, and the J-Tz-Q2D approach can extend the crack border dominance of the three-dimensional deep and shallow bend models along the crack front tip until perturbed by an elastic-plastic corner field. Practical implications The paper reports the limitation of the J-Tz approach, which is used to calculate the state of three-dimensional crack tip stresses in power law hardening materials. The results from this paper suggest that the characterization of the three-dimensional crack tip stress in power law hardening materials is still an open issue and requires other suitable solutions to solve the problem. Originality/value This paper demonstrates a thorough analysis of a three-dimensional elastic-plastic crack tip fields for geometries that are initially either fully constrained (positive T-stress) or unconstrained (negative T-stress) crack tip fields but, subsequently, the T-stress sign changes due to crack length reduction and specimen thickness increase. The J-Tz stress-based method has been tested and its dominance over the crack tip field is shown to be affected by the combined in-plane and the out-of-plane constraints and the corner field effects.

Fracture Analysis of Cracks in Orthotropic Materials Using ANSYS®

2006 ◽  
Author(s):  
A. O. Ayhan ◽  
A. C. Kaya ◽  
A. Loghin ◽  
J. H. Laflen ◽  
R. D. McClain ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Crack Tip ◽  
Transversely Isotropic ◽  
Fracture Analysis ◽  
General Purpose ◽  
Orthotropic Materials ◽  
Displacement Fields ◽  
Crack Tip Fields ◽  
Regular Manner ◽  
Orthotropic Properties

A methodology for performing two and three-dimensional fracture analyses in orthotropic materials using ANSYS software (“ANSYS”) is presented. The methodology makes use of analytically known crack tip fields in orthotropic materials and is implemented into a general purpose ANSYS macro. The ANSYS analysis, which takes into account the material orthotropy is performed in a regular manner by including the quarter point elements near the crack front. Then, in the post-processing module, the developed macro is run to associate the crack tip displacements with the orthotropic crack tip displacement fields to compute the mixed-mode stress intensity factors. Numerical examples are also presented that demonstrate application and validation of the procedure. These examples include an edge crack in an orthotropic strip and a surface crack in a transversely isotropic plate. The results show how the orthotropic fracture results may differ from those of isotropic fracture analysis. It is also shown that this difference can be dramatically big when the stress analysis is done using the orthotropic properties, whereas the fracture calculations are performed considering the crack tip fields for a crack in an isotropic material.

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