• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2005년도 춘계학술대회 논문집
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• pp.264-271
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• 2005

This study investigates the behavior of fatigue crack propagating between holes or holes filled with another materials. When holes or the holes bonded with another materials exist near center crack symmetrically, crack propagation rate is influenced by the bonding force of brazing part and the elastic modulus ratio of another material to matrix. It is experimentally and analytically confirmed that the center crack stops when its tip reaches near the center line of the holes and a small crack is initiated from the boundaries of holes or the holes filled with another materials and it propagates to final fracture. The mechanical behaviors of center crack near another materials are also investigated.

• 한국공작기계학회논문집
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• 제14권6호
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• pp.74-82
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• 2005

This study investigates the behavior of fatigue crack propagating between holes or holes filled with another materials. When holes or the holes bonded with another materials exist near center crack symmetrically, crack propagation rate is influenced by the bonding force of brazing part and the elastic modulus ratio of another material to matrix. It is experimentally and analytically confirmed that the center crack stops when its tip reaches near the center line of the holes and a small crack is initiated from the boundaries of holes or the holes filled with another materials and it propagates to final fracture. The mechanical behaviors of center crack near another materials are also investigated.

• 한국자동차공학회논문집
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• 제11권2호
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• pp.172-181
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• 2003

In this study, the stress intensity factor of center crack tip is calculated by the superposition method when it is surrounded by symmetrically distributed small cracks. The values of stress intensity factors of center crack tips are compared with those of the center crack tips calculated by the superposition method. These compared errors are influenced by the locations of distributed small cracks. These errors are inspected. When small cracks overlap and approach near the center crack tip, the effect of interaction caused by these cracks becomes noticeable and these errors become larger. In case of multiple distributed small cracks except this case, the stress intensity factor of the center crack tip is easily calculated by the superposition method.

• 한국자동차공학회논문집
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• 제13권6호
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• pp.63-69
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• 2005

For the case that center crack is surrounded by four small cracks which are symmetrically distributed around center crack, the same values of normalized stress intensity factor of center crack according to the position of the tip of small cracks are located on the smooth curve. And the stress intensity factor according to any position of small cracks can be sufficiently obtained from this curve. The plastic zones between distributed cracks are also investigated by changing the positions of nearly small cracks. The occurrence of plastic zone due to the interaction between center crack and small cracks are analyzed by finite element method. The mechanical behavior at the vicinity of crack tips is investigated by plastic areas. The changes of plastic zones according to positions of distributed cracks are drawn schematically. The safety of materials is also analyzed.

• 한국산학기술학회논문지
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• 제6권6호
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• pp.531-535
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• 2005

본 논문은 구멍 또는 이종 재료들로 채워진 구멍들 사이에 전파화는 피로 크랙의 거동을 연구한다. 중앙 크랙의 선단이 구멍의 중심선 가까이에 도달할 때 중앙 크랙은 멈추고 작은 크랙이 구멍이나 다른 이종 재료들로 채워진 구멍 주위로부터 발생하여서 최종 파단에 이르게 된다. 다른 이종 재료들 가까이에서의 중앙 크랙의 역학적 거동들이 또한 조사된다. 이러한 크랙이 진행하여 파괴에 이르는 현상을 컴플라이언스법으로 연구한다.

• 한국정밀공학회지
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• 제7권2호
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• pp.39-46
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• 1990

In this study, the mechanical behavious of a center crack which propagates between two holes in a panel are investigated. It is confirmed experimentally and analytically that a center crack stops and a small crack initiates from holes and propagates to fracture because of the compressive stress arising along the path of the fatigue crack propagation. Futhermore, it is noted that regardless of the configuration of the crack and the structure, Paris' law can be applied to the fatigue crack propagation.

• 대한수학회논문집
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• 제34권4호
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• pp.1353-1364
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• 2019

Modified Lagrange functional for solving an elastic problem with a crack is considered. Two formulations of a crack problem are investigated. The first formulation concerns a problem where a crack extending to the outer boundary of the domain. In the second formulation, we consider a problem with an internal crack. Duality ratio is established for initial and dual problem in both cases.

• Elastomers and Composites
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• 제54권4호
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• pp.313-320
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• 2019

A typical wear pattern was reported to resemble the fatigue crack growth behavior considering its mechanism, especially for amorphous rubbers such as styrene-butadiene rubber (SBR). In this study, the wear and crack growth rates were correlated using two separate experiments for carbon black and silica-reinforced selected rubber compounds. The wear rate was determined using a blade-type abrasion tester, where the frictional energy input during wearing was measured. The crack propagation rate was determined under different tearing energy inputs using a home-made fatigue tester, with a pure-shear test specimen containing pre-cracks. The rates of abrasion and crack propagation were plotted on a log-log scale as a function of frictional and tearing energies, respectively. Reasonable agreement was observed, indicating that the major mechanism of the abrasion pattern involved repeated crack propagation.

• 대한기계학회논문집
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• 제14권2호
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• pp.382-392
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• 1990

This study investigates the behavior of fatigue crack propagating between holes of holes filled with another materials. When holes of the holes filled with another materials are located symmetrically near a center crack, it is noted that the crack propagation rate is influenced by both the bonding force of the brazing part and the elastic modulus of another material. It is experimentally and analytically confirmed that the center crack stops when its tip reaches near the center line of the holes and a small crack is initiated from the boundaries of holes of the holes filled with another materials and it propagates to final fracture.

• 대한기계학회논문집A
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• 제20권10호
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• pp.3408-3414
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• 1996

This paper investigated plane strain stress intensity factors caused by thermal impact on a center-crack strip. The crack was aligned perpendicularly to the strip boundary. The problem was analysed by determining the dislocation density function in the singular integral equations formulated by the dislocation theory. Under the abrupt temperature change along the edge, the center crack behaved as a mode I crack due to the symmetric geometry. The value of maximum stress intensity factor monotonically increased until the ratio of dimensionless crack length approached to about 0.3, followed by gradual decrease. As a result, a critical corresponding crack length was determined.