• Transactions of the Korean Society of Mechanical Engineers
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• v.10 no.2
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• pp.198-207
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• 1986

This study investigates interlaminar fracture characteristics of Graphite/Epoxy composite (HFG Graphite/Epoxy) under mode I (opening mode), mode II (sliding mode) and mixed mode loading conditions. The effects on interlaminar fracture toughness due to different fiber orientations on the crack surface are also investigated. The antisymmetric test fixture proposed by M. Arcan is used for this test. Both critical stress intensity foctors and critical energy release rates were determined and several mixed mode fracture criteria were compared to the experimental data. Also fracture surfaces were investigaed to obtain informations on the fracture behaviors of Graphite/Epoxy composite by means of a scanning electron microscope(SEM).

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.103-103
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• 2004

실제 작용하는 하중상태는 요소의 형상과 작용하중의 복잡성 때문에 혼합모드 하중상태를 나타낸다. 또한 혼합모드 피로균열은 전파과정 동안 부재의 구속형상이나 외부 작용하중의 급격한 변화에 의해서도 영향 받게 된다. 이로 인하여 피로균열은 균열선단에서 지속적이면서 급격한 응력 재분배의 상태를 경험한다. 그러므로 다양한 응력 재분배 상태에서의 혼합모드 피로균열에 대한 고찰이 필요하다. 본 연구에서는 응력 재분배상태 하에서 나타나는 혼합모드 피로균열의 전파거동에 대한 특징이 실험적으로 고찰되었다.(중략)

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.7
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• pp.1217-1226
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• 2003

The purpose of this paper is to investigate fatigue crack behavior under shear(Mode II) loading. Various specimens and devices have been used in order to produce Mode II loading in fatigue experiments for shear crack propagation. But, there is not sufficient comparisons of experimental results between Mode II and others loading modes, because of characteristics of applied loads and specimens. So, compact tension shear(CTS) specimens were used in this paper to investigate the propagation behavior of Mode II by comparing the experimental results between loading modes. We firstly observed the characteristics which was showed in Mode II experiment using CTS specimens. The experimental results under Mode II loading were compared with fatigue crack behavior under Mode I and Mixed-mode I＋II loading. The characteristics for initiation and propagation behavior under Mode II loading was investigated by such comparisons.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.214-219
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• 2004

Crack tip behavior of single mode loading condition(mode I)depend on tensile loading component but one of mixed mode loading condition(mode I+II) have influenced on shear loading component like the practical structure. Because crack closure is caused by shear loading component under mixed-mode loading a research on the behavior in the stage of crack initiation and propagation require to be evaluate about crack closure effect by fatigue crack surface friction. For that reasion we examined the behavior at the crack tip by direct measuring method. Measured behavior at the crack tip was analyzed through vector crack tip displacement. As a result, crack propafation equation was corrected by considering with crack closure effect. In addition we compared fatigue fracture crack surface and crack closure level.

• Journal of the Korean Wood Science and Technology
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• v.21 no.2
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• pp.15-22
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• 1993

This study was carried out to investigate the fracture criterion of glulam. The mixed mode fracture of glulam was investigated by means of single edge notched specimens with various crack inclination in the longitudinal-radial plane. While fracture of wood is not completely understood, the study on linear-elastic fracture mechanics is a rational and valuable tool for studying the strength behavior of glulam. The results are summarized as follows : 1. Glue line has no effect on fracture strength. 2. There is a definite interaction between fracture toughness $K_I$ and $K_{II}$ during the mixed mode fracture of glulam. Several criterions for mixed mode failure were compared. The criterion was expressed in the following form: $(\frac{K_I}{K_{IC}})^2+(\frac{K_{II}}{K_{IIC}})^2=1$ 3. As crack inclination increases, $K_{IC}$ value and $K_{IIC}$ value decreases. The equations relating crack angle to $K_{IC}$ and $K_{IIC}$, respectively, were obtained as follows; $K_{IC}$ = -77.42${\gamma}$+153.72 ($R^2$ = 0.78) $K_{IIC}$ = -9.17${\gamma}$+34.90 ($R^2$ = 0.48)

• Proceedings of the Korean Nuclear Society Conference
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• 2001.10a
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• pp.262.1-262
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• 2001

• Proceedings of the KSME Conference
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• 2001.06a
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• pp.187-192
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• 2001

Cracks in mechanical joints is generally under mixed-mode and there is the critical inclined angle at which mode I stress intensity factor becomes maximum. In order to evaluate the fatigue life of cracks in mechanical joints, horizontal crack normal to the applied load and located on minimum cross section is major concern but critical inclined crack must also be considered. In this paper mixed-mode fatigue crack growth test is performed for horizontal crack and critical inclined crack in mechanical joints. Fatigue crack growth path is predicted by maximum tangential stress criterion using mode I and mode II stress intensity factors obtained from weight function method, and fatigue crack growth rates of horizontal and inclined crack are compared.

• Journal of the Korean Society of Industry Convergence
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• v.11 no.2
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• pp.59-64
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• 2008

Elements of a mechanical structure are getting from multi-axles stress. so fatigue characteristic experiment Shall execute in multi-axles stress state. it is very hard to apply according to forms of a testing machine and implementation. In this study, 2 axles fatigue testing machine did a design and Development. a new JIG developed to realize a mixed mode. a stress state in mixed mode of a specimen had each other comparison using the Finite element method to examine propriety of a new JIG.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.1
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• pp.78-84
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• 2015

The stress state acting on mechanical parts and structures is generally mixed stress. This complex stress state, which is subject to changes in the environment, will produce many. Cars running on roads with different road conditions will subject the automotive parts to combined stress state. In the x direction and the y direction, a different amplitude and frequency of the fatigue load can be present. However, the load amplitude for Mode I and Mode II in a 2-axis fatigue test is limited to a constant ratio; the load frequency is always the same for any mode. In this paper, it is verified how the variation of the load frequency for mode II affects the behavior of fatigue crack propagation under mixed mode.

• Journal of Welding and Joining
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• v.6 no.3
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• pp.43-55
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• 1988

An experimental study was carried out to identify the fatigue fractue behavior of weld zone in generally rolled steel for marine structure. The bending an shear loads were applied simultaneously on the specimens to simulate real load condition for marine structure. The effect of the stress intensity factor under mode I with II loading condition on the initiation and the propagation of a crack were investigated, with particular emphaiss on mode II. When the $K_{II}$ stress intensiy factor in mode II was applied under mode I load condition, the growth behavior of a crack seems to be affected mainly by the anisotropic characteristic of materials. Especially, when the crack was located in and near the weld zone and parallel to th weld line, the propagation behaviour was turned out to be quite different from that of the base metal along the direction transverse to the weld line. In general, the propagation veiocity of the cracks in and near the weld zone was found to be slower that the velocity in base metal.