• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계학술대회논문집
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• pp.612-615
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• 2005

This studies presented truss frame which use aluminum beam by damage model. Truss frame which each joint part is contracted by bolt contracted conclusion of each bolt by 3.0 N/m. And measured impedance change that appear making bolt 0.5 N/m on damage condition 8 times. Compares impedance change of 5 segments that was set by measurement area and displayed result. To measure torque change of bolt, other damage model did not apply.

• 한국정밀공학회지
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• 제11권2호
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• pp.189-196
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• 1994

Quality assurance in the process of manufacturing high strengh bolt sets used in the frictional joints of structures in one of important concern to users as well as to manufactures. In case of occurrences of either defective or low-quality products, even if they are quite rare, some systematic means of localizing the cause-characteristics and matching to corresponding production process is necessary. Control chart of torque factor is the primary indicatir in finding defectiveness of the products. Use of correlation diagrams ofnhardness of the bolt set presents in part a way of screening the cause. Retest data of the bolt set provide additional ideas of localizing the cause, for which theoretical background is presented in this regard. A process-characteristics matrix relating the causes of low quality to the corresponding process of manufacturing, which is of prime importance for the feedback control of production, is also proposed. Finally general features of control to assure quality of the set is described.

• 기계저널
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• 제56권10호
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• pp.49-52
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• 2016

이 글에서는 터빈 Casing Bolt 분해조립 시 신기술 가열분해 공법을 적용하여, 정비기간 단축 및 Bolt 파손을 방지한 사례에 대해 소개하고자 한다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2011년도 춘계학술대회 논문집
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• pp.57-58
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• 2011

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년도 제31회 추계학술대회논문집
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• pp.293-296
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• 2008

현재의 많은 유도무기들은 발사관에 장착되어 보관 및 이동되다가 필요시 발사된다. 발사관이란 유도탄 즉 미사일등이 외부환경에 노출되지 않도록 유도탄을 둘러싸고 있는 일종의 케이스이며 또한 유도탄 발사시 가이드 역할을 동시에 수행한다. 유도탄과 발사관을 연결하는 방법으로 흔히 사용되는 것으로 탄고정장치를 사용하는데 대표적인 파이로 부품이 폭발볼트이다. 폭발볼트는 화약의 폭발력에 의해 볼트몸체가 절개됨으로써 볼트에 의해 결합되고 있던 부분이 분리된다. 하지만 기존의 폭발볼트는 분리시 파편, 화염 및 pyro-shock이라는 악작용을 수반하므로 사용상 제한을 가지고 있다. 이와 같은 문제점을 해결하기 위하여 압력카트리지에서 발생하는 압력을 분리력으로 사용할 수 있는 분리장치 즉 볼타입 볼트를 개발하게 되었다. 본 연구에서는 볼타입볼트의 분리현상을 분석하여 분리볼트의 분리성능 안전율을 정량적으로 제시하였다.

• Tribology and Lubricants
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• 제35권1호
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• pp.65-70
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• 2019

Self-loosening of bolts owing to external forces occurs in several machines that are clamped by bolts and nuts. This study focuses on the self-loosening of the aiming bolt of the head lamp in a vehicle. It is important to prevent the aiming bolt from self-loosening as it has a decisive effect on the angle of the head lamp. A nut clamped with a bolt, known as a retainer, is made of plastic and has a partial screw thread. In addition, a transverse load has a considerable impact on the self-loosening of a bolt. We concentrate on the self-loosening of a bolt by a transverse load. The aim of this study is to define the limits of the external force that loosen the bolt. Based on the above conditions, we derive a theoretical equation and develop a numerical analysis program that can calculate the limiting forces for self-loosening. To verify the developed program, we design a test device that can measure the self-loosening by applying sliding forces to the aiming bolt. Using this method, we can draw the following conclusions. First, the developed testing device is suitable to prove the theory for calculating the self-loosening force. Second, the equation confirms the relationship of bolt self-loosening between resistance torque and shear force. Finally, the equation obtains the minimum value of the resistance torque required to decrease the change in the angle of the head lamp, thereby improving the possibility of increasing the stability of the head lamp.

• 한국전산구조공학회논문집
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• 제32권4호
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• pp.265-272
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• 2019

본 연구에서는 영상기반 딥러닝 및 이미지 프로세싱 기법을 이용한 볼트풀림 손상검출 기법을 제안하였다. 이를 위해 먼저, 딥러닝 및 이미지 프로세싱 기반 볼트풀림 검출 기법을 설계하였다. 영상기반 볼트풀림 검출 기법은 볼트 이미지 검출 과정 및 볼트풀림 각도 추정 과정으로 구성된다. 볼트 이미지의 검출을 위하여 RCNN기반 딥러닝 알고리즘을 이용하였다. 영상의 원근왜곡 교정을 위해 호모그래피 개념을 이용하였으며 볼트풀림 각도를 추정을 위하여 Hough 변환을 이용하였다. 다음으로 제안된 기법의 성능을 검증을 위하여 거더의 볼트 연결부 모형을 대상으로 볼트풀림 손상검출 실험을 수행하였다. 다양한 원근 왜곡 조건에 대하여 RCNN 기반 볼트 검출기와 Hough 변환 기반 볼트풀림 각도 추정기의 성능을 검토하였다.

• Composites Research
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• 제36권4호
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• pp.259-263
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• 2023

This study investigated the open hole tensile (OHT) properties of carbon fiber/epoxy composites and compared them to bolt joint tensile (BJT) properties. The net nominal modulus and strength (1376 MPa) were found to be higher than the gross nominal strength (1041 MPa), likely due to increasing hole size. The OHT and BJT specimens exhibited similar stiffness, as expected without bolt rotation causing secondary bending. OHT specimens experienced a sharp drop in stress indicating unstable crack propagation, delamination, and catastrophic failure. BJT specimens failed through shear out on the bolt side and bearing failure on the nut side, involving fiber kinking, matrix splitting, and delamination, resulting in lower strength compared to OHT specimens. The strength retention of carbon fiber/epoxy composites with open holes was 66%. Delamination initiation at the hole's edge caused a reduction in the stress concentration factor. Filling the hole with a bolt suppressed this relieving mechanism, leading to lower strength in BJT specimens compared to OHT specimens. Bolt joint efficiency was calculated as 15%. The reduction in strength in bolted joints was attributed to fiber-matrix splitting and delamination, aligning with Hart Smith's bolted joint efficiency diagram. These findings contribute to materials selection and structural reliability estimation for carbon fiber/epoxy composites. They highlight the behavior of open hole and bolt joint configurations under tensile loading, providing valuable insights for engineering applications.

• Geomechanics and Engineering
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• 제11권2호
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• pp.177-195
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• 2016

To secure the stability of geotechnical infrastructures and minimize failures during the construction process, a number of support systems have been introduced in the last several decades. In particular, stabilization methods using steel bars have been widely used in the field of geotechnical engineering. Rock bolt system is representative support system using steel bars. Pre-stressing has been applied to enhance reinforcement performance but can be released because of the failure of head or anchor sections. To overcome this deficiency, this paper proposes an innovative support system that can actively reinforce the weak ground along the whole structural element by introducing an active tension bolt containing a spring unit to the middle of the steel bar to increase its reinforcement capacity. In addition, the paper presents the support mechanism of the active tension bolt based on a theoretical study and employs an experimental study to validate the performance of the proposed active tension bolt based on a down-scaled model. To examine the feasibility of the active tension unit in a pillar, the paper considers a pullout test and a small-scale experimental model. The experimental results suggest the active tension bolt to be an effective support system for pillar reinforcement.

• 한국기계가공학회지
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• 제12권5호
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• pp.57-66
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• 2013

This study investigates structural and vibration analyses due to the change of bolt Numbers on models 1 and 2 of flange couplings connected with both sides of axis. As maximum equivalent stresses of models 1 and 2 are 122.05 and 102.3 MPa respectively by the basis of bolt, these stresses are within the allowable stress of this model and the safety of bolt design is verified. As maximum equivalent stresses of models 1 and 2 are 196.2 and 196.4 MPa respectively by the basis of body, these stresses are within the allowable stress of this model and the safety of body design is verified. Through natural frequency analysis, maximum displacements of model 1 and 2 are shown at the frequencies of 6565.1 and 6614.9 Hz respectively. Maximum displacements in cases of models 1 and 2 are shown at harmonic frequencies of 7760 and 7840 Hz at real loading conditions. By putting these study results together, the durability of vibration at model 2 with bolt numbers of 8 becomes better than model 1 with bolt numbers of 6. These study results can be effectively utilized with the design on flange coupling by anticipating and investigating prevention and durability against its damage.