• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.7
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• pp.765-770
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• 2014

This paper describes the study on a method for improving the structural durability of bolted joints applied to a composite bogie frame. In this study, three bolted joints with and without inserts and screw threads were selected for determining the effect of the inserts, using experiment and analysis. The structural performances of the proposed bolted joints were compared and evaluated using the test method prescribed by the ASTM D5961 standard. The results revealed that the bolted joint having an insert shape without the screw thread offered improved durability for application to a composite bogie frame. Furthermore, the structural integrity of the frame comprising the bolted joints was evaluated using finite element analysis according to the JIS E 4207 standard. The Tasi-Wu and Von-Mises failure criteria were used for determining the failure of the composite structure and bolted joints, respectively. A sub-modeling technique was introduced for investigating the performance of the bolted joints in greater detail. The analysis results demonstrated that the Tasi-Wu failure index of the composite structure near the bolted joints was reduced by approximately one-half after applying an insert without the screw thread. This implies that the structural durability of the bolted joints of a composite bogie frame could be improved by using a metal insert without the screw thread.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.14 no.1
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• pp.21-28
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• 2001

기계구조물을 슬리브 없이 볼트-너트 체결하는 경우 판재의 강성에 대해서는 많은 연구가 진행되어 신뢰할 수 있는 이론이 보고되어 있다. 그러나 토목 분야에서 많이 사용되는 슬리브가 있는 볼트-너트 체결부에 대한 연구는 미진한 상태이다. 본 연구에서는 슬리브가 있는 경우 볼트-너트로 체결된 판재의 강성을 계산하는 공식을 유도하고 이를 콘크리트 구조물의 예에 적용하였다. 제안된 공식의 결과를 단순합산식과 유한요소법에 의한 결과와 비교하여 그 타당성과 유용성을 밝혔다. 본 연구에서 제안한 공식은 슬리브가 있는 체결부의 판재 강성을 계산하는데 유용하게 사용할 수 있을 것이다.

• Journal of Aerospace System Engineering
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• v.13 no.6
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• pp.26-35
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• 2019

In this paper, progressive failure analysis is performed on composite joints widely used in various industries such as the aerospace industry. The analysis was conducted on single bolted joints to confirm its reliability and in succession on double-bolted composite joints as well to study the characteristics of progressive failure. Hashin failure criteria and EGDM (energy based gradual degradation model) were used for the analysis. Failure variables are defined by four failure modes, respectively. According to the variables, stiffness degradation has been calculated. As a result of comparing the test and analysis results of single-bolted joints, the error was below 5% and it showed that the analytical results are rather credible. Also, the parametric analysis consequences were obtained conducting the process-progressive failure analysis on the double-bolted composite joints considering edge-distance ratio (e/d ratio) and bolt spacing.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.8
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• pp.917-923
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• 2014

Subminiature joining bolts are required for the electronic parts of gadgets such as mobile phones and watch phones. During the miniaturization of bolt heads, it is difficult to obtain sufficient joining force owing to the risk of shear fracture of the bolt head or severe plastic deformation on the bit region. In this study, the maximum joining torque for the bit depth was predicted using finite element analysis. A shear fracture test was conducted on a wire used in bolt forming. The results of this test were subjected to finite element analysis and a fracture criterion was obtained by comparing the experimental and analysis results. The shear fracture of the bolt head during joining was predicted based on the obtained criterion. Furthermore, the maximum joining torque was predicted for various bit depths. Fracture on the boundary between the bolt head and thread was found to occur in lower joining torque as bit depth increases.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.936-938
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• 2017

In this paper, the progressive failure analysis of a bolted composite joint which is used in combustion tubes of projectiles and weapon systems is performed. Hashin's failure criterion is considered as fiber tensile failure mode, fiber compressive failure mode, matrix tensile failure mode, and matrix compressive failure mode for this analysis. And this criterion is used to make user subroutine, UMAT. Through the progressive failure analysis we predicted failure strength and compared failure strength with specimen test result.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.8
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• pp.759-764
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• 2017

This research investigated the hygrothermal effect on the strength of bolt jointed section and moisture contents of composites exposed to hygrothermal environment for composite aircraft radome. The decrease in strength in the test environment is mainly attributed to the change in the material properties of the matrix due to temperature and moisture. The composite specimens were tested in three different environmental conditions: RTD(room temperature and dry), CTD(cold temperature and dry) and ETW(elevated temperature and wet). The failure mode of the bolt jointed composite specimens were studied using tests and finite element analysis. Finite element analysis reasonably predicted the failure load and mode of the joints. A reliability-based design was carried out for the bolt jointed composites of radome.

• Composites Research
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• v.26 no.2
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• pp.91-98
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• 2013

A three-dimensional finite analysis method was proposed to predict the failure of composite double-lap bolted joints, which is based on the stiffness degradation method using damage variables and Hashin's three-dimensional failure criteria. Ladeveze's theory using damage variables to consider the matrix/shear damage was combined with stiffness degradation in fiber direction. Four different failure modes were considered including matrix compression/shear, matrix tension/shear, fiber compression, and tension failures. The friction between bolt and composite and the clamping force were considered using a commercial finite element software ABAQUS. The damage model was incorporated using the user-defined subroutine of the software. The predicted result was verified with the existing test result for bearing tension double shear and showed the deviation ranging 7~16% from test results.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.36 no.4
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• pp.221-232
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• 2023

This paper presents a novel convolutional neural network (CNN)-based approach for predicting bolt clamping force in the early bolt loosening state of bolted structures. The approach entails tightening eight bolts with different clamping forces and generating frequency responses, which are then used to create a similarity map. This map quantifies the magnitude and shape similarity between the frequency responses and the initial model in a fully fastened state. Krylov subspace-based model order reduction is employed to efficiently handle the large amount of frequency response data. The CNN model incorporates a regression output layer to predict the clamping forces of the bolts. Its performance is evaluated by training the network by using various amounts of training data and convolutional layers. The input data for the model are derived from the magnitude and shape similarity map obtained from the frequency responses. The results demonstrate the diagnostic potential and effectiveness of the proposed approach in detecting early bolt loosening. Accurate bolt clamping force predictions in the early loosening state can thus be achieved by utilizing the frequency response data and CNN model. The findings afford valuable insights into the application of CNNs for assessing the integrity of bolted structures.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.429-432
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• 2000

본 논문의 정수기는 영동산 일라이트를 필터의 주된 재료로 사용하였다. 구조는 여과필터를 교체하여 사용할 수 있도록 된 정수기의 필터 케이스 및 여과 방법에 관한 것으로써, 보다 상세하게는 필터 케이스가 분리, 결합이 간편한 본체와 마개로 구성되어 있다. 이 본체는 1차 여과부와 2차 여과부로 분리되어 물이 1차 여과부의 상부를 통해 인입되어 2차 여과부의 상부로 연결되도록 되어 있어 동일한 크기 내에서 여과구간이 2배로 길어져 여과 효율이 우수한 동시에 물인입구와 물배출구가 동일한 방향에 위치하여 다수 개의 필터 케이스를 연결할 때 필터 케이스의 간격을 좁힐 수 있어 필터 케이스의 설치면적이 좁다. 본체와 마개의 체결방식은 볼트 체결방식으로 되어 있으며, 마개는 플라스틱 재질이어서 본체에 마개를 단단히 체결하면 누수가 방지되도록 되어있다. 즉, 정수기의 필터하우징 성능과 영동산 일라이트가 가지고 있는 기능성을 이용한 필터를 사용함으로써 정수기에서 요구되어지는 정수능력을 가진 정수기를 개발 보고한다.

• Journal of Korean Society of Steel Construction
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• v.27 no.1
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• pp.53-61
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• 2015

The tension type joint is a mechanically very efficient connection method, as it directly uses the load capacity of base metal or high tension bolt, the reduction of the number of drilling hole and fastening and the fatigue resistance. It is applied to the joint of girder and cross beam, horizontal joints of towers, beam to column joints, the secondary member joints of deck floor ends, and brackets. In this paper, static load tests for the T-type tension joint were conducted to investigate the structural behavior of the joint. The parameters were bolt diameter, flange thickness, and the reduction of clamping force of the joint. The failure modes and load capacity of joints and the effects of flange thickness, bolt diameter and clamping force were investigated.