• Journal of the Korean Wood Science and Technology
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• 제20권2호
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• pp.61-72
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• 1992

This study was carried out to investigate the fracture behavior and the fracture criterion of yellow lauan(Shorea spp.), when has used for furniture and wood structures, and to offer a reliability for wood structure and basic data for wood fracture criterion in experiments which are fracture tested under mode I, mode II and mixed mode loading condition. The results were summarized as follows; 1. Fractures in specimens which have inclined grain in yellow lauan procedeed from crack tip in the radial direction along the grain. 2. In yellow lauan, $K_{IC}RL$ was 42.1kg/$cm^{3/2}$ and $K_{IIC}RL$ was 15.8kg/$cm^{3/2}$. 3. The fracture criteria of lauan were; ($K_I/K_{IC}$)+($K_{II}/K_{IIC}$)=1 in RL system with inclined grain at $45^{\circ}$, ($K_I/K_{IC}$)+$(K_{II}/K_{IIC})^2$=1 with inclined grain at $15^{\circ}$ and $(K_I/K_{IC})^2$+$(K_{II}/K_{IIC})^2$=1 with inclined grain at $30^{\circ}$, $60^{\circ}$, $75^{\circ}$ and $90^{\circ}$, respectively. 4. The fracture criterion of wood could vary with the species, and the load applying condition. In order to measure the fracture criterion strictly, along with standardization of specimen geometry a large amount of experimental data is needed. 5. $K_{IC}$(critical stress intensity factor) can be predicted by grain angle. As the grain inclined angle increased, $K_{IC}$ and $K_{IIC}$ are increased.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.1754-1759
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• 2007

Propagation of a mixed-mode crack in Soda-Lime silica glass using Movable Cellular Automata (MCA) method is demonstrated in this study. In MCA method, special fracture criterion is used to describe the process of crack initiation and propagation. Comparison between MCA and other crack initiation criteria results are made. The crack resistance curves and bifurcation angles under different loading angles are found. In comparisons with results of maximum circumferential tensile stress criterion, MCA result showed the sufficient agreement.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 춘계학술대회 논문요약집
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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)

• 한국항공우주학회지
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• 제33권10호
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• pp.35-41
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• 2005

재료주축과 경사진 중앙균열을 내포하는 직방성 복합재료 내 균열문제를 해석하였다. 이 균열체에는 외부경계에서 2축방향으로 작용하는 하중을 받고 있다. 복합재료 내 초기균열의 진전각을 예측하기 위하여 수직응력비 이론을 적용하였으며, 균열진전각에 미치는 2축하중과 섬유재료주축의 영향을 분석하였다. 본 해석을 통하여 균열진전각은 수평하중에 많은 영향을 받고 있으며, 또한 균열경사각과 섬유배향각에도 큰 영향을 받음을 확인하였다.

• Structural Engineering and Mechanics
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• 제74권5호
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• pp.601-609
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• 2020

In this article, the Strain Energy Density (SED) averaged over a well-defined control volume at a notch edge was applied in combination with the Equivalent Material Concept (EMC) to assess the fracture behaviors of some keyhole-notched specimens made of a High-Density Polyethylene (HDPE-PE80) material under mixed-mode loading conditions. An experimental program was performed and 54 new experimental data were totally provided. Additionally, different loading mode ratios were regarded by changing the inclination angles of the notches with respect to the applied load directions. The results obtained from the determined criteria were in good agreement with those of the experimental data.

• 한국재료학회지
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• 제14권5호
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• pp.322-327
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• 2004

Copper-based leadframe sheets were oxidized in two kinds of hot alkaline solutions to form brown-oxide or black-oxide layer on the surface. The oxide coated leadframe sheets were molded with epoxy molding compound (EMC). After post mold curing, the oxide-coated EMC-leadframe joints were machined to form sandwiched Brazil-nut (SBN) specimens. The SBN specimens were used to measure the fracture toughness of the EMC/leadframe interfaces under mixed-mode (mode I + mode II) loading conditions. Fracture surfaces were analyzed by various equipment to investigate failure path. The results revealed that the failure paths were strongly dependent on the oxide type. In case of brown oxide, hackle-type failure was observed and failure path lay near the EMC/CuO interface with a little inclining to CuO at all case. On the other hand, in case of black oxide, quite different failure path was observed with respect to the distance from the tip of pre-crack and phase angle. Different failures occurred with oxide type is presumed to be due to the difference in microstructure of the oxides.

• 대한기계학회논문집
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• 제10권2호
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• pp.198-207
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• 1986

본 연구에서는 Fig.1과 같이 시편 부위에 균일응력분포가 작용하도록 M.Arcan 등에 의해 제시된 비대칭형상의 시편고정물에 층간균열을 가진 시편을 부착한 다음 하중각도를 바꾸어가며 모우드 II뿐 아니라 혼합모우드 및 모우드 I까지도 실험 할 수 있는 실험장치를 사용하여 균열면에서의 섬유방향이 〔0/0〕이고 초기균열길이비가 0.4, 0.5, 0.6인 시편의 모우드I, 혼합모우드 및 모우드II 층간파괴인 성치들을 실험 적으로 구해 혼합모우드 파괴결정조건식들에 적용시켜 보았다. 또한 균열면에서의 섬유방향이 〔0/0〕, 〔0/30〕, 〔0/45〕및 〔0/60〕인 경우의 층간파괴인성치와 이때 의 파괴현상에 대해 관찰하였다.

• 대한기계학회논문집
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• 제7권2호
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• pp.145-152
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• 1983

An adhesively bonded anisotropic structure containing a part-through crack subjected to in-plane mixed mode deformations is investigated. The problem is reduced to a pair of Fredholm integral equations of the second kind by mathematical analysis. By solving these equations numerically stress intensity factors k$_{1}$ and k$_{2}$ are presented. Two cases are considered with respect to fiber orientations. Case one is to fix the fiber orientations of sound plate bonded to cracked plate with various fiber orientations. The other is to vary fiber orientations for both plates. As boundary conditions, tension and shear loading respectively, are applied to bonded anisotropic plates to observe mixed mode deformations.

• International Journal of Precision Engineering and Manufacturing
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• 제9권4호
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• pp.66-70
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• 2008

The propagation of a mixed-mode crack in soda-lime silica glass is modeled by movable cellular automata (MCA). In this model, a special fracture criterion is used to describe the process of crack initiation and propagation. The results obtained using the MCA criterion are compared to those obtained from other crack initiation criteria, The crack resistance curves and bifurcation angles are determined for various loading angles. The MCA results are in close agreement with results obtained using the maximum circumferential tensile stress criterion.

• Structural Engineering and Mechanics
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• 제29권3호
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• pp.301-310
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• 2008

Applications of fracture mechanics in the strength analysis of ceramic materials have been lately studied by many researchers. Various test specimens have been proposed in order to investigate the fracture resistance of cracked bodies under mixed mode conditions. Double Cleavage Drilled Compression (DCDC) specimen, with a hole offset from the centerline is a configuration that is frequently used in subcritical crack growth studies of ceramics and glasses. This specimen exhibits a strong crack path stability that is due to the strongly negative T-stress term. In this paper the maximum tensile stress (MTS) criterion is employed for investigating theoretically the initiation of brittle fracture in the DCDC specimen under mixed mode conditions. It is shown that the T-stress has a significant influence on the predicted fracture load and the crack initiation angle. The theoretical results suggest that brittle fracture in the DCDC specimen is controlled by a combination of the singular stresses (characterized by KI and KII) and the non-singular stress term, T-stress.