• International Journal of Automotive Technology
• /
• 제6권3호
• /
• pp.293-303
• /
• 2005

Bonded dissimilar materials are being increasingly used in automobiles, aircraft, rolling stocks, electronic devices and engineering structures. Bonded dissimilar materials have several material advantages over homogeneous materials such as high strength, high reliability, light weight and vibration reduction. Due to their increased use it is necessary to understand how these materials behave under stress conditions. One important area is the analysis of the stress intensity factors for interface cracks emanating from circular holes in bonded dissimilar materials. In this study, the bonded scarf joint is selected for analysis using a model which has comprehensive mixed-mode components. The stress intensity factors were determined by using the boundary element method (BEM) on the interface cracks. Variations of scarf angles and crack lengths emanating from a centered circular hole and an edged semicircular hole in the Al/Epoxy bonded scarf joints of dissimilar materials are computed. From these results, the stress intensity factor calculations are verified. In addition, the relationship between scarf angle variation and the effect by crack length and holes are discussed.

• 한국항공우주학회지
• /
• 제36권10호
• /
• pp.954-961
• /
• 2008

원형 손상구멍이 있는 날개 주위 유동장에 대한 실험연구를 수행하였다. 손상은 시위의 10% 직경의 시위에 수직인 원형 구멍으로, 구멍 중심은 1/4 시위 혹은 1/2 시위에 위치하고 있다. 입자영상유속계에 의한 유동장 측정과 날개의 아래 및 윗면에서의 정압장을 시위를 기준으로 한 레이놀즈수 Rec=2.85×105에서 측정하였다. 입자영상유속계에 의한 유동 측정 결과 손상 구멍 주위에는 두 가지 형태의 유동구조가 형성되었다. 하나는 약한 제트로 손상 구멍 하류에서 부착된 후류가 생성된다. 다른 하나는 받음각 증가에 의한 강한제트에 의한 것으로 손상구멍으로부터 자유흐름으로 관통되어 접근하는 경계층 흐름을 박리시켜 역류가 있는 박리 후류구조를 생성한다. 날개면 압력 자료는 원형 손상 구멍 근처에서 큰 압력변화를 보여주었다. 이러한 압력변화는 손상구멍이 앞전 쪽에 가까울수록 증가하였다.

• Composites Research
• /
• 제29권6호
• /
• pp.388-394
• /
• 2016

Fiber reinforced plastic (FRP) composites have drawn increasing attentions worldwide for decades due to its outstanding properties. Stress concentration factor (SCF) as an essential parameter in materials science are critically considered in structure design and application, strength assessment and failure prediction. However, investigation of stress concentration in FRP composites has been rarely reported so far. In this study, three resource-conserving analyses (Isotropic analysis, Orthotropic analysis and Finite element analysis) were introduced to plot the $K_T^A-d/W$ curve for E-glass/epoxy composite plate with the geometrical defect of circular hole placed centrally. The plates were loaded to uniaxial direction for simplification. Finite element analysis (FEA) was carried out via ACP (ANSYS composite prepost module). Based on the least squares method, a simple expression of fitting equation could be given based on the simulated results of a set of discrete points. Finally, all three achievable solutions were presented graphically for explicit comparison. In addition, the investigation into customized efficient SCFs has also been carried out for further reference.