• 대한기계학회논문집A
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• 제41권10호
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• pp.983-989
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• 2017

본 논문에서는 첨단복합재의 볼트단일접합 베어링강도에 대한 시험적 평가 결과를 수록하였다. 볼트단일접합 시험은 stabilized 접합과 unstabilized 접합에 대하여 수행하였다. Stabilized 접합은 접합부 면외회전을 제한하는 접합이다. Unstabilized 접합은 면외변위를 제한하지 않는 접합이다. 볼트 단일접합에서 적층판의 베어링강도 값은 적층판 내 적층각 $0^{\circ}$, $+45^{\circ}$, $-45^{\circ}$ 및 $90^{\circ}$ 비율에 영향이 없음을 보여준다. 볼트접합부 면외거동의 영향으로 unstabilized 볼트 단일접합 베어링 강도값이 stabilized 볼트 단일접합 베어링 강도값 보다 작음을 보여주고 있다. 본 논문에 사용된 복합재료는 $177^{\circ}C(350^{\circ}F)$에서 경화되는 Carbon/Epoxy UD Tape 프리프레그이다. 표준각 $0^{\circ}$, $+45^{\circ}$, $-45^{\circ}$ 및 $90^{\circ}$ 층으로 적층된 8종류의 적층판에서 총 112개 볼트단일접합 시험시편을 구성하였다. Stabilized 접합과 unstabilized 접합의 시험방법은 ASTM-D-5961M 규정을 사용하였다.

• 한국정밀공학회지
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• 제20권1호
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• pp.172-178
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• 2003

Two types of bolted lap joints, one with a viscoelastic layer and the other without the viscoelastic layer were chosen to analyze the dynamic characteristics of the joints with the mechanical properties of the bolts in the joints are considered as computational variables. The finite element method was used along with the modal testing to verify the PEM model. The results in the bolted lap joints reveal that the higher the Young's modulus for the bolts we use the higher the natural frequencies we obtain fur the joints. However, the natural frequency differences in the first and second mode are not substantial but become noticeable in the higher modes. Lower natural frequencies were obtained for the bolted lap joints with the viscoelastic layer when compared with those of the bolted lap joints without the viscoelastic layer. And the differences in the natural frequencies for the two types of joints are relatively small in the first and second mode whereas in the higher mode the differences become significant. The loss factors were observed to be significant especially in the second mode for the bolted lap joints with the viscoelastic layer.

• Composites Research
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• 제23권1호
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• pp.37-43
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• 2010

이 연구에서는 볼트로 겹침이음된 펄트루젼 복합재의 접합부에 대한 구조적 거동을 실험적 연구를 통해 조사하였다. 펄트루젼 복합재 접합부의 구조적 거동 조사에 앞서 재료의 역학적 성질을 파악하기 위해 펄트루젼 복합재의 인장 및 전단실험을 수행하였고, 이를 바탕으로 볼트의 수와 배열을 변수로 3종류의 겹침이음 시편을 제작하였다. 겹침이음 접합부 실험은 접합부를 중심으로 인장하중이 작용하도록 하중을 재하하였고, 하중증가에 따른 접합부의 구조적 거동 및 파괴모드를 조사하였다. 실험결과 접합부에 대한 파괴는 대부분 전단파괴로 나타났으며, 실험을 통해 얻어진 데이터를 분석하여 설계를 위한 기초자료로 활용될 수 있도록 하였다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집B
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• pp.624-629
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• 2001

Two types of bolted lap joints, one with a viscoelastic layer and the other without the viscoelastic layer were chosen to analyze the dynamic characteristics of the joints with the mechanical properties of the bolts of the joints being taken as computational variables. The finite element method was used along with the impact hammer technique to verify the FEM model. The results in the bolted lap joints reveal that the higher the Young's Modulus for the bolts are the higher the natural frequencies results for the joints. However, the natural frequency differences in the first and second mode are not substantial but become noticeable in the higher modes. Lower natural frequencies were obtained for the bolted lap joints with the viscoelastic layer when compared with those of the bolted lap joints without the viscoelastic layer. And the differences in the natural frequencies for the two types of joints are relatively small in the first and second mode whereas in the higher mode the differences become significant. The loss factors were observed to be significant especially in the second mode for the bolted lap joints with the viscoelastic layer.

• Smart Structures and Systems
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• 제5권4호
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• pp.329-344
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• 2009

Ultrasonic chaotic excitations combined with sensor prediction algorithms have shown the ability to identify incipient damage (loss of preload) in a bolted joint. In this study we examine a physical experiment on a single-bolt aluminum lap joint as well as a three-dimensional physics-based simulation designed to model the behavior of guided ultrasonic waves through a similarly configured joint. A multiple bolt frame structure is also experimentally examined. In the physical experiment each signal is imparted to the structure through a macro-fiber composite (MFC) patch on one side of the lap joint and sensed using an equivalent MFC patch on the opposite side of the joint. The model applies the waveform via direct nodal displacement and 'senses' the resulting displacement using an average of the nodal strain over an area equivalent to the MFC patch. A novel statistical classification feature is developed from information theory concepts of cross-prediction and interdependence. This damage detection algorithm is used to evaluate multiple damage levels and locations.

• Structural Engineering and Mechanics
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• 제72권5호
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• pp.557-568
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• 2019

Accurate modeling of contact interface in bolted joints is crucial in predicting the dynamic behavior for bolted assemblies under external load. This paper presents a contact pressure distribution based non-uniform virtual material method to describe the joint interface of assembly structure, which is connected by sparsely distributed multi-bolts. Firstly, the contact pressure distribution of bolted joints is obtained by the nonlinear static analysis in the finite element software ANSYS. The contact surface around bolt hole is divided into several sub-layers, and contact pressure in each sub-layer is thought to be evenly. Then, considering multi-asperity contact at the micro perspective, the relationship between contact pressure and interfacial virtual material parameters for each sub-layer is established by using the fractal contact theory. Finally, an experimental platform for the dynamic characteristics testing of a beam lap structure with double-bolted joint is constructed to validate the efficiency of proposed method. It is found that the theoretical results are in good agreement with experimental results by impact response in both time- and frequency-domain, and the relative errors of the first four natural frequencies are less than 1%. Furthermore, the presented model is used to examine the effect of rough contact surface on dynamic characteristics of bolted joint.

• 한국구조물진단유지관리공학회 논문집
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• 제16권1호
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• pp.9-17
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• 2012

본 연구는 소규모 지하통로, 저류시설 및 지중구조물에 많이 적용되고 있는 파형강판구조의 이음부강도를 실험적으로 평가하고자 하였다. 대골형파형강판을 사용하는 지중 강구조물은 압축력에 대하여 충분한 안정성을 확보하여야 한다. 그러나 현장에서 볼트 연결되는 이음부가 강판의 두께, 캐스킷, 와셔, 슬롯홀과 같은 연결상세에 따라 강도가 변화함에도 불구하고 이음부강도에 대한 실험적 이론적 결과가 설계에 반영할 수 있을만큼 충분히 축적되지 않은 상태이다. 본 연구에서는 다양한 연결상세를 적용한 경우의 이음부 압축거동을 실험적으로 분석하였다. 연구결과 강판의 두께가 증가함에 따라 강판지압파괴에서 볼트전단의 형태로 파괴 형태가 변화하는 것으로 나타났으며, 6.omm 이상의 플레이트에서는 개스킷과 슬롯홀을 적용한 이음부가 와셔를 적용한 경우보다 효과적인 거동을 보이는 것으로 관찰되었다.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2005년도 추계학술발표대회 논문집
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• pp.57-60
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• 2005

Composite-to-aluminum joins were tested to get failure loads and modes for three types of joins; adhesive bonding, bolt fastening, and adhesive-bolt hybrid joining. Film type adhesive FM73 and paste type adhesive Cytec EA9394S were used for aluminum and composite bonding to make a double-lap joint. A digital microscope camcorder was used to monitor the failure initiation and propagation. It was found that the hybrid joining is an effective method to strengthen the joint when the mechanical fastening is stronger than the bonding as in the case of using the paste type adhesive. On the contrary, when the strength of the bolted joint is lower than the strength of the bonded joint as in the joint with the film type adhesive, the bolt joining contribute little to the hybrid joint strength.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2005년도 춘계학술발표대회 논문집
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• pp.94-97
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• 2005

The strength of aluminum 7075 and carbon composite hybrid joints was studied for adhesive, bolt, and the adhesive-bolt combined joints. Several hybrid joint specimens were tested to get the failure load and modes for three types of the joints. Adhesive Cytec EA9394S was used for aluminum and carbon bonding. Failure load of the adhesive-bolt combined joint was 94 % of the sum of the failure load of the separately bonded and bolted joints. Hybrid joint also showed more stable failure behavior than the simple adhesive or bolted joint.

• 한국항공우주학회지
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• 제31권1호
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• pp.8-17
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• 2003

항공기 주구조에서 맞대기중첩연결(Butt Lap Joint) 구조는 저속균열성장 개념의 손상허용설계를 한다. 이러한 연결부 구조는 볼트나 리벳 구멍 가장자리의 부재간 접촉면에서 프레팅에 의한 피로균열이 발생되어 다지점 균열성장 거동을 하는 경우가 많다. 본 연구에서는 초기 모서리균열을 내재한 볼트연결 맞대기중첩연결 구조시편에 프레팅 조건을 달리하여 비행하중스펙트럼 하에서 피로균열 성장거동을 실험적으로 분석하고 잔여강도를 비교하여 프레팅이 균열성장과 손상허용성에 미치는 영향을 고찰하였다. 또한 기존의 응력강도식으로 모서리균열의 성장패턴을 예측하고 실험결과와 비교 분석하였다.