• Steel and Composite Structures
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• v.16 no.2
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• pp.203-220
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• 2014

Stress intensity factors are numerically investigated for interfacial edge crack between two dissimilar composite plates jointed with single side composite patch. Variation of stress intensity factor under Mode I loading condition is examined for different material models and fiber orientation angles of composite plates and patch. ANSYS 12.1 finite element analysis software is used to obtain displacements of crack surfaces in the numerical solution and repaired plates are modeled in three dimensions. Obtained results are presented in the form of graphs. It is found that fiber orientation angle of composites is an effective parameter on interfacial stress intensity factor.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.23 no.6 s.165
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• pp.961-967
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• 1999

A model is constructed to evaluate the mode III stress intensity factor(SIF) for orthotropic three-layered material with a center crack subjected to uniform anti-plane shear loading. A mixed boundary value problem is formulated by Fourier integral transform method and a Fredholm integral equation of the second kind is derived. The integral equation is numerically analyzed to evaluate the effects of the ratio of shear modulus, strength of each layer and crack length to layer thickness on the stress intensity factor.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.7
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• pp.134-142
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• 2001

The integrals $J_k$(k=1,2) in the rectilinear anisotropis body in 2-D were determined using Lekhnitskii formalism. The relationship between $J_k$ and stress intensity factors are implified by the important equation between elastic compliance. The numerical evaluation of stress intensity factor for the single edge crack in mixed mode is determined by superposing known exact solutions.

• Proceedings of the KSME Conference
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• 2001.11a
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• pp.234-239
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• 2001

The stress intensity factors have been widely used in numerical studies of crack growth direction. However in many cases, omissive terms of the series expansion are quantitatively significant, so we consider the computation of such terms. For this purpose, we used the finite element method with isometric quadratic quarter-point elements. For examples, infinite square plate with a slant crack subjected to a uniaxial load is analyzed. The numerical analysis were performed for the wide range of crack tip element lengths and inclined angles. The numerical results obtained are compared with the theoretical solutions. Also they were accurate and efficient.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.4
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• pp.806-812
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• 1988

When laser interference method is used to measure stress intensity factor with experiment, crack molded from teflon crack molding method is better than the crack manufactured through fatigue test. It is known that center distance between two indentations which is best for detecting the laser interference fringe order is about 80.mu.m with photodetector used in this research. Errors with measurement of stress intensity factor through laser interference are between 2% and 11%, therefore, experimental process and method developed in this research can be used with obtaining the more precision experimental data for stress intensity factors.

• Structural Engineering and Mechanics
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• v.26 no.1
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• pp.99-109
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• 2007

A cracked composite specimen, comprised of an epoxy and an aluminium plate, was fractured under a tensile load. In this paper, two crack configurations were investigated. The first was an artificial center crack positioned in the epoxy plate parallel to the material interface. The other was for two edge cracks in the epoxy plate, again, parallel to the interface. A tensile test was carried out by gradually increasing the applied load and it was verified that the cracks always moved suddenly in an outward direction from the interface. The d/a ratio was gradually reduced to zero, and it was confirmed that the maximum stress intensity factor value for the artificial center crack, $K_{{\theta}{\theta}}^{max}$, approached that of an artificial interface crack,$K_{{\theta}{\theta}}^{ifc\;max}$ (where: 2a is the crack length and d is the offset between the crack and interface). The same phenomenon was also verified for the edge cracks. Specifically, when the offset, d, was reduced to zero, the maximum stress intensity factor value, $K_{{\theta}{\theta}}^{max}$, approached that of an artificial interface edge crack.

• International Journal of Precision Engineering and Manufacturing
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• v.8 no.3
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• pp.60-63
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• 2007

Weight functions in fracture mechanics represent the stress intensity factors as weighted averages of the externally impressed boundary tractions and body forces. We extended the weight function theory for cracked linear elastic materials to calculate the notch stress intensity factor of a notched structure with anti-plane deformation. The well-known method of deriving weight functions by differentiation cannot be used for notched structures. By combining an appropriate singular field with a regular field, we derived weight functions for the notch stress intensity factor. Closed expressions of weight functions for notched cylindrical bodies are given as examples.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.3
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• pp.393-404
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• 1997

SPATE(Stress Pattern Analysis by Thermal Emission) can be effectively used to analyze the stress distributions of isotropic structure under the repeated load by non-contact. In this research, the measuring method and the measuring concept of stress intensity factor of isotropic material by SPATE are suggested. The validity of the method and the concept was certified through SPATE experiment.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.10
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• pp.3224-3233
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• 1996

SPATE(Stress Pattern Analysis by Thermal Emission) can be effectively used to analyze the stress distribution of the orthotropic structure under the repeated load by non-contact. In this research, the measuring conception and method of stress intensity factor of orthotropic material using SPATE are suggested. The relationships between the maximum values of SPATE signal and $1/\sqrt{X'}$ (or $1/\sqrt{y'}$) are theoretically established in the vicinity of crack tip of the orthotropic material. It is certified through SPATE experiment that their linear quality is very excellent.

• Journal of Mechanical Science and Technology
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• v.17 no.2
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• pp.254-268
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• 2003

The explicit formulation of the J-integral and the M-integral is constructed in terms of the stress intensity factor and the higher order stress coefficients for Mode II cracks under small or large scale yielding. Furthermore, the stress intensity factor and the higher order stress coefficients as well are computed with the aid of the two-state J- and the M-integral, which is found to be accurate and efficient. It is found that the contribution from the higher order singularities to the J-integral is closely related to the configuration of the plastic zone.