• Advances in aircraft and spacecraft science
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• 제5권5호
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• pp.595-613
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• 2018

The objective of our study is to analyze the behavior of bonded, riveted and hybrid (bonded / riveted) steel / steel assemblies by tensile tests and to show the advantage of a hybrid assembly over other processes. the finite element method with the ABAQUS numerical code was used to model the fracture behavior of the different assemblies. Cohesive zone models (CZM) have been adopted to model crack propagation in bonded joints using a bilinear tensile separation law implemented in the ABAQUS finite element code. The riveted assemblies were modeled with the XFEM damage method identified in this ABAQUS numerical code. Both CZM and XFEM methods are combined to model hybrid assemblies. The results are consistent with the experimental results and make it possible to guarantee the validity of the applied numerical model. The use of a hybrid assembly shows a high resistance compared to other conventional methods, where the number of rivets has been highlighted. The use of the hybrid assembly improves mechanical strength and increases service life compared to a single lap joint and a riveted joint.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 춘계학술대회 논문집
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• pp.326-331
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• 2005

In this study, bearing response in single lap riveted joint is investigated by menas of single lap shear specimens with different types of adherend and fastener. Single lap shear specimen consists of adherend of SUS403 and carbon fabric/epoxy composite. Rivet of Avdel 2691 with 9.6mm diameter is used. Two types of fastener in single lap riveted joint are considered. One is a single lap shear specimen with single fastener, and the other is a single lap shear specimen with double fasteners. Especially, in case of single lap shear specimen with single fastener, the width of the specimen is varied as 2D, 3D, 4D, 6D at a fixed edge distance of 3D. Also the edge distance of the specimen is varied as 1.0D, 1.5D, 2.0D, 2.5D, 3.0D at a fixed width of 4D. In case of single lap shear specimen with double fasteners, two types of specimen are considered. One is a specimen with the width of 6D and edge distance of 3D. The other is a specimen with the width of 4D and edge distance of 2D. Here D designates the hole diameter for riveted joint.

• Advances in aircraft and spacecraft science
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• 제4권1호
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• pp.1-19
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• 2017

Fatigue life prediction of a multi-row countersunk riveted lap joint was performed numerically. The stress and strain conditions in a highly stressed substructure of the joint were analysed using a global/local finite element (FE) model coupling approach. After validation of the FE models using experimental strain measurements, the stress/strain condition in the local three-dimensional (3D) FE model was simulated under a fatigue loading condition. This local model involved multiple load cases with nonlinearity in material properties, geometric deformation, and contact boundary conditions. The resulting stresses and strains were used in the Smith-Watson-Topper (SWT) strain life equation to assess the fatigue "initiation life", defined as the life to a 0.5 mm deep crack. Effects of the rivet-hole clearance and rivet head deformation on the predicted fatigue life were identified, and good agreement in the fatigue life was obtained between the experimental and the numerical results. Further crack growth from a 0.5 mm crack to the first linkup of two adjacent cracks was evaluated using the NRC in-house tool, CanGROW. Good correlation in the fatigue life was also obtained between the experimental result and the crack growth analysis. The study shows that the selected methodology is promising for assessing the fatigue life for the lap joint, which is expected to improve research efficiency by reducing test quantity and cost.

• 한국안전학회지
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• 제31권3호
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• pp.1-7
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• 2016

In this study, static and fatigue tests on the self-piercing riveted (SPR) joint were conducted using cross-shaped specimens with aluminum alloy (Al-5052) sheets. Mixed mode loading was achieved by changing the loading angles of 0, 45, and 90 degrees using a special fixture to evaluate the static and fatigue strengths of the SPR joints under mixed mode loading conditions. Simulations of the specimens at three loading angles were carried out using the finite element code ABAQUS. The fatigue specimens failed in an interfacial mode where a crack initiated at the upper sheet and propagated along the longitudinal direction and finally fractured Maximum principal stress, von-Mises effective stress failed to correlate the fatigue lifetimes at three loading angles. However, the equivalent stress intensity factor was found to be appropriate to correlate the fatigue lifetimes at three loading angles.

• Structural Engineering and Mechanics
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• 제70권4호
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• pp.467-477
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• 2019

The objective of this work is to analyze by traction tests, the mechanical behavior of an assembly of type metal / metal by various assembly processes; bonding, riveting and hybrid, on the one hand to show the advantage of a hybrid assembly with respect to the other processes, and on the other hand, to analyze by the finite element method the distribution of the stresses in the various components of the structure and to demonstrate the effectiveness of the use of a hybrid assembly with respect to other processes. The number of rivets has been considered. The results show clearly that the value of the different stresses is reduced in the case of a hybrid junction and that the number of rivets in an assembly can be reduced by using a hybrid joint.

• Steel and Composite Structures
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• 제43권1호
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• pp.19-30
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• 2022

The static strength and fatigue crack resistance of the aircraft skin structures depend on the materials used and joint type. Most of the commercial aircraft's skin panel structures are made from aluminium alloy and carbon fibre reinforced epoxy. In this study, the fatigue resistance of four joint configurations (metal/metal, metal/composite, composite/composite and composite/metal) with riveted, adhesive bonded, and hybrid joining techniques are investigated with experiments and finite element analysis. The fatigue tests were tension-tension because of the typical nature of the loads on aircraft skin panels susceptible of experimenting fatigue. Experiment results suggest that the fatigue life of hybrid joints is superior to adhesive bonded joints, and these in turn much better than conventional riveted joints. Thanks to the fact that, for hybrid joints, the adhesive bond provides better load distribution and ensures load-carrying capacity in the event of premature adhesive failure while rivets induce compressive residual stresses in the joint. Results from FE tool ABAQUS analysis for adhesive bonded and hybrid joints agrees with the experiments. From the analysis, the energy release rate for adhesive bonded joints is higher than that of hybrid joints in both opening (mode I) and shear direction (mode II). Most joints show higher energy release rate in mode II. This indicates that the joints experience fatigue crack in the shear direction, which is responsible for crack opening.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.727-730
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• 2001

In many structures a common method of construction is to make use of bolted or riveted joints. With this type of joint the load is transmitted through a pin from one section of the structure to another. Fatigue cracks often start from the edges of holes, due to local stress concentration. In order to predict the fatigue crack growth, the stress intensity factor K for hole-edge cracks should be available. In this paper the stress intensity factors are computed for cracks in bolt-joint region considering the contact condition.

• 비파괴검사학회지
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• 제21권2호
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• pp.163-168
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• 2001

접착제와 리벳으로 접합된 항공기 판재의 접합부는 접합 불량, 크랙, 피로 결함이나 부식등에 의해 손상되고 열화될 수 있으며 이런 결함을 전 영역에 걸쳐서 신속하고도 신뢰성 있게 검사하는 것은 항공기 안전을 위해 매우 중요하다. 본 연구에서는 이를 위해 항공기용 알루미늄 판재의 랩 스플라이스 접합 연결부의 접합 품질을 비접촉 방식으로 수행할 수 있는 초음파 비파괴 평가법을 제안한다. 여기서는 레이저를 이용해 램파를 발생시키고 비접촉식 트랜스듀서 (공기정합 용량형 트랜스듀서)를 이용해 피치-캐치 방식으로 검사한다. 레이저 소스로는 Q-스위치된 Nd:YAG 레이저가 이용되며 배열 형태의 직선 슬릿을 갖는 마스크를 이용해 특정 모드의 램파를 발생시켜 이용하였다. 접합부의 한 쪽에서 발생된 레이저 여기 초음파는 판을 따라 전파하여 접합부를 지나 반대편에서 수신되고 수신된 신호의 특성과 접합부의 품질과의 관련성을 조사하였다.

• 대한기계학회논문집A
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• 제24권9호
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• pp.2344-2352
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• 2000

Mechanical joints such as bolted or riveted joints are widely used in mechanical components. The reliable determination of the stress intensity factors for cracks in bolted joints is needed to evaluate the safety and fatigue life of them. The weight function method is an efficient technique to calculate the stress intensity factors for various loading conditions because only the stress analysis of an uncracked model is required. In this paper the mixed-mode stress intensity factors for cracks in bolted joints are obtained by weight function method, in which the coefficients of weight function are determined by finite element analyses for reference loadings. Critical inclined angle that mode I stress intensity factor becomes maximum is determined and the effects of crack length and the magnitude of clearance on critical inclined angle are investigated.

• 한국산학기술학회논문지
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• 제22권2호
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• pp.794-801
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• 2021

이 연구는 electric resistance element spot welding 프로세스를 도입하여 알루미늄 합금-강철의 이종 접합부의 기계적 강도 및 내식성을 향상시키기 위해 수행되었다. SPFC980Y 강철과 Al5052-H32가 각각 모재로써 적용되었고, S20C 강철은 리벳 element로써 음각과 양각의 형상으로 구분되며, Al5052-H32에 전기 저항 스폿 용접을 위해 리벳팅 되어 6.5 kA의 전류와 250 kgf/㎠의 가압력으로 접합되었다. 그 결과, 음각된 S20C element는 스폿 용접 공정 후 불안정한 너깃이 형성되는 반면, 양각된 S20C의 경우, 구조적으로 건전한 접합부로 건전한 내식성 및 탁월한 기계적 특성이 얻어졌다. FEM 시뮬레이션의 도입으로, 음각과 양각의 계면의 접합 특성이 수치적으로 밝혀졌으며, 시뮬레이션 결과는 미세조직 발달 양상을 수치적으로 뒷받침하였다. 이 연구는 element 스폿 용접된 H32-A5052 이종 접합부의 기계적 강도 및 부식 신뢰성에 대해 체계적으로 분석되었으며, 이 공정은 금속재료뿐만 아니라, 경량 비전도성 비철/비금속계 재료에도 적용 될 수 있기 때문에, 차세대 차체 경량화의 양산 기술로 확장 될 수 있다.