• Composites Research
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• v.25 no.6
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• pp.186-190
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• 2012

With the wide application of fiber-reinforced composite material in aero-structures and mechanical parts, composite joint have become a very important research area because they are often the weakest sites in composite structures. In this paper, the failure strengths of the bolted joint and pin joint which have variable hole clearance were evaluated and compared. From the tests, the first failure loads of the bolted joint and pin joint with $880{\mu}m$ hole clearance have decreased by 24.2 % and 51.3 % compared to those of joints with $0{\mu}m$ hole clearance, respectively. Also, the failure index of the joints were calculated by the finite element method and compared with experimental results.

• Proceedings of the KAIS Fall Conference
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• 2011.12b
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• pp.620-623
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• 2011

안전핀은 기계적으로 과도한 힘이 작용할 때, 파손되어 다른 구성품 및 사람을 보호하는 역할을 하며 이는 전자/전기 시스템에서 Fuse와 같은 역할이다. 안전핀은 재설기의 구동시스템 또는 항공기 Pushback Bar 등에 사용된다. 본 논문에서는 항공기 착륙장치에 적용된 안전핀의 역할과 파손 확률 계산 방안에 대해 소개하고자 한다.

• Proceedings of the KSME Conference
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• 2005.11a
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• pp.125.2-125.2
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• 2005

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.520-522
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• 2011

In this paper, the bearing strengths and fracture behaviors of the pin-jointed carbon fiber/epoxy composites were investigated through pin loading test. The composites were fabricated by a filament winding process, and two types of laminated patterns were considered. According to the results, type 1 pattern revealed a net-tension failure mode, whereas type 2 pattern exhibited a bearing failure mode. Also, acoustic emission energy of the type 2 pattern was higher than that of the type 1 pattern. Therefore, the type 2 pattern was found to be structurally safer than the type 1 pattern.

• Composites Research
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• v.15 no.2
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• pp.1-10
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• 2002

The strength of glass/epoxy fabric joints under pin-loading is estimated based on the characteristics length method and experiment. To investigate the effect of finite element idealization for the contact between pin and laminate, three modeling cases are analyzed; assuming the cosine load distribution around the contact area, constraining the radial displacement at the hole boundary, and using the contact element. To study the effect of failure criteria, Tsai-Wu and Yamada-Sun methods are applied on the characteristic curve. The results of the nonlinear analysis using the contact element showed good agrements with experimental data in both laminates made of uni-directional prepreg tapes and fabrics. In terms of failure criteria, Tsai-Wu method showed better agreement with experimental results than the one by Yamada-Sun laminate.

• Journal of Advanced Marine Engineering and Technology
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• v.41 no.1
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• pp.118-124
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• 2017

To investigate and analyze the cause of the failure of the connecting rod bolt and the crank pin bearing bolt of the diesel engine of this study, the following results were obtained through site surveying, the investigation of literature referring to similar failures, testing and inspection of the fracture surface, and the experience of the researchers. The fractured crank pin bearing bolt of the diesel engine is estimated to be damaged later than the connecting rod bolt. From the shape of fracture surface, it is evident that the failed connecting rod bolt is fractured by fatigue failure due to abnormally repeated loads (e.g. loosening of the connecting bolt, etc.), and is not failed by brittle fractures due to the impact load. The surface of the U-nut on the fractured connecting rod bolt has been worsening due to the improper use of lubricant (agent for prevention of thread fixing) and no usage of separating the each connecting rod on each cylinder. Moreover, there is the possibility that those poor surface conditions of the fractured connecting rod bolt have affected the failure of the connecting rod bolt of the main engine. And it could be assumed that the mechanical characteristic and manufacturing process of the failed connecting rod bolt and crank pin bearing bolt, which were made by a domestic company, conform to the design requirements for those bolts.

• Composites Research
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• v.25 no.3
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• pp.65-69
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• 2012

The main objective of this study is to investigate the effect of metal z-pinning on the failure behavior of cocured composite single-lap joints. Three different pin diameters (0.3, 0.5, and 0.7 mm) and three pin areal densities (0.5, 2.0, and 4.0%) were examined. The specimens were fabricated by T700-12K-31E#2510 unidirectional prepreg from Toray. Stainless steel pins were used for z-pinning. Test results showed that except one case with extremely low pin density of 0.5%, all other z-pinned joints exhibited lower initial crack stresses than those of the unpinned joint. However the ultimate strength of the z-pinned joint increased up to 45% at most. Furthermore, even after the complete failure of the joint, the z-pins sustained the carried load to a certain degree experiencing large deformation and provided the stable fracture behavior for the composite joint.

• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.4
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• pp.9-15
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• 2012

In this paper, the bearing strengths and fracture behaviors of the pin-jointed carbon fiber/epoxy composites were investigated through pin loading test with acoustic emission technique. The composites were fabricated by a filament winding process, and three types of laminated patterns were considered. Type 1 was fabricated with stitch, Type 2 was fabricated without stitich and Type 3 was fabricated with prepregs. According to the results, bearing strength of Type 1 was 3.3% lower than that of Type 2 and that of Type 3 was highest. Type 1 and Type 2 revealed a net-tension failure mode, respectively, whereas Type 3 pattern exhibited a bearing failure mode. Also, acoustic emission energy of the Type 3 was higher than that of the Type 1 and Type 2. Therefore, the Type 3 was found to be structurally safer than the Type 1 and Type 2.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.1
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• pp.25-33
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• 2003

The failure load and mode of the unidirectional and fabric hybrid composite laminate joints are studied by test and finite element analysis. Test is conducted for the specimens with nine various geometries under pin loading. Finite element analysis is performed considering the contact and friction effects between the pin and laminate by MSC/NASTRAN. Failure is estimated by Tsai-Wu and Yamada-Sun criteria on the characteristic curve. While the failure of the specimens with the small width and edge length are much affected by the joint geometry, the geometry effects are negligible in the specimens with large width and edge length. Finite element analysis based on the characteristic length method reasonably predicts the failure load and mode of the joints.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.411-413
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• 2012

This study has been investigated about hygrothermal environmental effects on the pin-joined carbon/epoxy composites through acoustic emission technique. The specimens were classified as three types for pin loading test : Base (before immersion), RT (room temperature immersion), HT ($75^{\circ}C$ immersion). As a results, the bearing strength of RT specimens was weakly decreased than that of base specimens. The bearing strength of HT specimens was greatly decreased than that of Base and RT specimens due to effects of simultaneous moisture and higher temperature. Also, the results from cumulative hit of acoustic emission indicated that AE events induced by matrix cracks of HT specimens was lower than that of base specimens.