• Tribology and Lubricants
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• 제29권5호
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• pp.286-290
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• 2013

When a threaded fastener is tightened, the torque-tension relationship is highly sensitive to two friction components: thread friction and head friction. In this study, we carried out friction experiments and analyses to determine the optimum clamping torque setting for bolt joints. First, we measured the coefficients of thread friction and head friction under the same running conditions of the bolt clamping process for lubricated and non-lubricated bolts. We also measured axial tension through bolt clamping tests using lubricated and non-lubricated bolts attached to a strain gauge. Finally, we compared the experiment and theoretical results.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집A
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• pp.419-424
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• 2001

The purpose of this study is comparing cold expansion method with interference fit. Cold expansion method and interference fit of fastener hole is using in the aerospace industry. These treatment lead to an improvement of fatigue life to the compressive residual stresses developed on the hole surface. But Research is nothing to about difference effect of between cold expansion method and interference fit. So In this paper, It is shown that Comparing cold expansion method with interference fit. and It is further shown that residual stress distribution according to plate thickness.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 하계학술대회 논문집 B
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• pp.1168-1170
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• 1993

EHV underground transmission cable characterized by low loss and bulk capacity should have high reliability to be protected fully from external damages, not to speak of its quality. In 345kV underground transmission lines of our country, the usage of frie protection trough is standardized. Fire protection trough consists of combination of trough body, spacer, shutting board, fastener, and etc. and it is required to have a high level of fire-retardant characteristics and mechanical strength. Since 1992, we, GoldStar Cable, with collaboration of Lucky, have participated in the development of fire protect ion trough and completed the type test of manufacturing site and will be supposed to go into mass product within 1993.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 II
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• pp.940-944
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• 2001

Shock environments are generally classified two categories; One is mechanical shock environments encountered in handling, transportation, and service environments. The other is pyrotechnic shock (or pyroshock) environments generally initiated by firing of an ordnance item to separate or release a structural member of fastener. The objective of this paper is to present a set of shock test methods - specific characteristics induced by many shock test devices, test objects properties, and shock environments. In addition, it is introduced the application of shock test in Korean aerospace development program and others with shock test facilities of Korea Aerospace Research Institute.

• 한국군사과학기술학회지
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• 제22권4호
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• pp.452-459
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• 2019

In order to design and manufacture structures such as a guided missile, assembly process with fastener is an essential method of fabrication. In this study, the dynamic characteristics of a cylindrical structure with bolted joints were studied using experimental methods. The change of the natural frequency of the structure with the change of the fastening method and the tightening torque were measured by the test and the finite element analysis was performed using the stiffness model of the fastening part according to the fastening method and compared with the test results.

• Steel and Composite Structures
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• 제20권4호
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• pp.869-887
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• 2016

The socket-spigot template supporting system is widely used in engineering applications in China. As a newer type of support structure, there has been growing research interest in its bearing capacity. In this paper, four vertical bearing capacity tests were carried out on the basic mechanical unit frame of a socket-spigot template supporting system. The first goal was to explore the influence of the node semi-rigid degree and the longitudinal spacing of the upright tube on the vertical bearing capacity. The second objective was to analyze the displacement trend and the failure mode during the loading process. This paper presents numerical analysis of the vertical bearing capacity of the unit frames using the finite element software ANSYS. It revealed the relationship between the node semi-rigid degree and the vertical bearing capacity, that the two-linear reinforcement model of elastic-plastic material can be used to analyze the socket-spigot template supporting system, and, through node entity model analysis, that the load transfer direction greatly influences the node bearing area. Finally, this paper indicates the results of on-site application performance experiments, shows that the supporting system has adequate bearing capacity and stability, and comments on the common work performance of a socket and fastener scaffold.

• 한국구조물진단유지관리공학회 논문집
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• 제26권4호
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• pp.11-19
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• 2022

본 연구에서는 기계식 커플러의 이음성능을 향상시키기 위해 다른 접합방식을 가진 두 가지의 새로운 커플러를 개발하였다. 두 가지 방식의 기계식 이음장치에 대하여 응력 해석을 수행하였다. 커플러의 재료특성, 접합방식, 내부 조임쇠의 경사길이를 변수로 최대 인장강도의 영향성을 분석하기 위해 일축인장시험을 수행하였다. 일축인장시험결과를 만족하는 시험체를 대상으로 KS D 0249에 의거하여 정적내력시험 및 반복하중 시험을 수행하였다. 이에 대한 연구결과는 다음과 같다. (1) 커플러의 인장강도와 내부 조임쇠의 경사길이는 최대 인장강도에 영향을 끼친다. (2) 연결 방식에 따라 접합된 철근의 강성, 슬립량, 강성감소율에 영향이 있다. 연구결과는 새롭게 제안된 향상된 기계식 이음장치의 현장 적용에 대한 가능성을 검증하였다.

• Structural Engineering and Mechanics
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• 제53권5호
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• pp.867-880
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• 2015

Mechanical fastening is still one of the main methods used for joining components. Different techniques have been applied to reduce the effect of stress concentration of notches like fastener holes. In this work we evaluate the feasibility of combining laser shock peening (LSP) and cold expansion to improve fatigue crack initiation and propagation of open hole specimens made of 6061-T6 aluminum alloy. LSP is a new and competitive technique for strengthening metals, and like cold expansion, induces a compressive residual stress field that improves fatigue, wear and corrosion resistance. For LSP treatment, a Q-switched Nd:YAG laser with infrared radiation was used. Residual stress distribution as a function of depth was determined by the contour method. Compact tension specimens with a hole at the notch tip were subjected to LSP process and cold expansion and then tested under cyclic loading with R=0.1 generating fatigue cracks on the hole surface. Fatigue crack initiation and growth is analyzed and associated with the residual stress distribution generated by both treatments. It is observed that both methods are complementary; cold expansion increases fatigue crack initiation life, while LSP reduces fatigue crack growth rate.

• 대한기계학회논문집A
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• 제41권4호
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• pp.257-262
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• 2017

최근 스마트 폰, 스마트 와치 등과 같은 전자기기의 크기가 작아지면서, 그에 사용되는 체결 볼트의 크기 또한 작아지고 있다. 초소형 나사는 제품을 체결하는 데 있어 충분한 체결 토크나 풀림 방지효과를 갖지 못한다. 그래서 초소형 나사의 체결력과 풀림방지 효과를 유지 및 강화하는 연구가 필요하다. 본 연구에서는 초소형 나사의 풀림방지 효과를 강화하기 위해 나사의 머리 밑 면에 쎄레이션 형상을 추가하여 그 효과를 분석하였다. 쎄레이션 볼트는 풀림과정에서 피체결체 윗면을 변형시켜 풀림 방지 턱을 생성해 풀림을 방지하는 역할을 한다. 쎄레이션 개수와 체결 깊이를 변수로 하여 그 영향을 분석하고 풀림 방지 성능에 미치는 영향을 확인하였다.

• 한국산학기술학회논문지
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• 제16권6호
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• pp.3692-3697
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• 2015

나사는 나선형의 홈으로 구성된 체결용 기계요소이다. 최근의 모바일 기기의 소형화 추세로 인하여 나사의 소형화 및 경량화 요구도 크게 증가하고 있는 실정이다. 우수한 기계적 성질과 높은 정밀도의 나사를 생산하기 위해서는 금형 및 공정설계가 성공적으로 수행되어야 한다. 본 연구에서는 유한요소해석을 통하여 초소형 나사의 머리부 냉간 단조 성형에 대한 공정설계를 수행하였다. 특히, 금형의 형상과 마찰력이 성형에 미치는 영향을 분석하기 위하여 실험계획법을 적용하였고, 그 결과 마찰력이 성형 시 발생하는 접힘 결함의 지배적인 요인임을 밝혀내었다. 이러한 결과로부터 금형 형상을 개선하였고, 개선된 금형으로 단조 실험을 수행하였고, 실험 결과로부터 접힘 결함 불량이 해소된 것을 확인하였다.