• 한국정밀공학회지
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• 제29권10호
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• pp.1070-1077
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• 2012

Virtual machine tools have been magnified recently as manufacturers could estimate performances of machine tools before design and manufacturing of them. However, it requires much time and efforts to make FEM models and predict precision of machine tools well because machine tools are composed of many joints such as bolt joints, LM joints, rotational bearing joints and mounts. Especially, we have studied computational modeling methods of bolt joints to predict precision of machine tools well in this paper. Stiffness and damping coefficients of bolt joints are investigated and generalized with respect to fasten forces through experiments and FEM analysis. Matrix 27 element of ANSYS is used and bolt joints are simplified as square areas with 8 nodes to apply stiffness and damping simultaneously. Additionally, coordinate transformation of matrix 27 for bolt joints is induced to apply to skewed bolt joints of machine tools and evaluate it using FEM analysis.

• 대한기계학회논문집A
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• 제25권3호
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• pp.495-501
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• 2001

In this paper, a new technique which models the joints characteristics through reduction of DOFs of structures with joints using component mode synthesis (CMS) method is proposed. Bolt joints are modeled by mass-spring systems. Also generalized mass and stiffness matrices for this models are introduced. Because bolt joints have influence on eigenvalues of structures, exact eigenvalues from modal test are used. The results show that the behaviors of structures with bolt joints depend to a large extent on the translational DOFs and not on rotational DOFs of mass and stiffness matrices of bolts. Furthermore it is confirmed that lumped mass-spring systems as models of bolt joints are effective models considering the facts that joint characteristics converged to constant values in some iterations and eignevalues from proposed method are in good agreement with ones from modal test.

• 대한기계학회논문집A
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• 제33권8호
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• pp.819-825
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• 2009

An open frame structure is fastened by bolt joints for strength and shock attenuation. Therefore the full finite element model of an open frame structure should be properly modeled including bolt joints for strength analysis of the frames and joint assemblies which are operated under multi-loading conditions such as driving, drop, inertia and torsional loads. Then the joints and frames must satisfy the specified allowable strength constraints. Because the full finite element model has a large number of elements to perform strength analysis, a detailed fine bolt analysis seems to be very expensive. Therefore bolts of the full finite element model are approximately modeled by coupling method to constrain degree of freedoms between adjacent nodes. However, the coupling method can exaggerate stress results at the constrained nodes. Thus a detailed bolt analysis and a theoretical/experiential formula of bolts for a worst bolt joint are performed using reaction force applied both bolt and bolt joint. Finally, the results from the two methods are compared and discussed to verify the safety of the open frame structure.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.523-528
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• 2008

An open frame structure is fastened by bolt joints for strength and shock attenuation. Therefore the full finite element model of an open frame structure should be properly modeled including bolt joints for strength analysis of the frames and joint assemblies which are operated under multi-loading conditions such as driving, drop, inertia and torsional loads. Then the joints and frames must satisfy the specified allowable strength constraints. Because the full finite element model has a large number of elements to perform strength analysis, a detailed fine bolt analysis seems to be very expensive. Therefore bolts of the full finite element model are approximately modeled by constraints equations to constrain degree of freedoms between adjacent nodes. However, the constraints equation method can exaggerate stress results at the constrained nodes. Thus a detailed bolt analysis and a theoretical/experiential formula of bolts for a worst bolt joint are performed using reaction force applied both bolt and bolt joint. Finally, the results from the two methods are compared and discussed to verify the safety of the open frame structure.

• Structural Engineering and Mechanics
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• 제89권1호
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• pp.61-75
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• 2024

Strengthening of hollow structural sections using through-bolts is a cost-effective and straightforward approach. It's a versatile method that can be applied during both design and service phases, serving as a non-disruptive and budget-friendly retrofitting solution. Existing research on axially loaded hollow sections T-joints has demonstrated that this technique can amplify the joint strength by 50%, where single bolt could enhance the strength of the joint by 35%. However, there's a gap in understanding their use for K-joints. As the behavior of K-joints is more complex, and they are widely existent in structures, this study aims to bridge that gap by conducting comprehensive parametric study using finite element analysis. Numerical investigation was conducted to evaluate the effect of through bolts on K-joints focusing on using single through bolt to achieve most of the strengthening effect. A full-scale parametric model was developed to investigate the effect of various geometric parameters of the joint. This study concluded the existence of optimal bolt location to achieve the highest strength gain for the joint. Moreover, a rigorous statistical analysis was conducted on the data to propose design equations to predict optimal bolt location and the corresponding strength gain implementing the verified by finite element models.

• Steel and Composite Structures
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• 제18권6호
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• pp.1423-1450
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• 2015

The paper presents the details and results of an experimental study on bolted end-plate joints of industrial type steel building frames. The investigated joints are commonly used in Lindab-Astron industrial buildings and are optimized for manufacturing, erection and durability. The aim of the research was to provide an experimental background for the design model development by studying load-bearing capacity of joints, bolt force distribution, and end-plate deformations. Because of the special joint details, (i.e., joints with four bolts in one bolt-row and HammerHead arrangements), the Eurocode 3 standardized component model had to be improved and extended. The experimental programme included six different end-plate and bolt arrangements and covered sixteen specimens. The steel grade of test specimens was S355, the bolt diameter M20, whereas the bolt grade was 8.8 and 10.9 for the two series. The end-plate thickness varied between 12 mm and 24 mm. The specimens were investigated under pure bending conditions using a four-point-bending test arrangement. In all tests the typical displacements and the bolt force distribution were measured. The end-plate plastic deformations were measured after the tests by an automatic measuring device. The measured data were presented and evaluated by the moment-bolt-row force and moment-distance from centre of compression diagrams and by the deformed end-plate surfaces. From the results the typical failure modes and the joint behaviour were specified and presented. Furthermore the influence of the end-plate thickness and the pretension of the bolts on the behaviour of bolted joints were analysed.

• 한국산학기술학회논문지
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• 제10권8호
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• pp.2055-2061
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• 2009

고장력볼트 마찰이음에서 모재 및 덮개판을 과대공 제작하였을 경우 연결부의 내하력에 다소의 변화가 발생 될 수 있다. 본 논문에서는 고장력볼트 마찰이음에서 표준공과 과대공에 따라 미끄럼하중과 미끄럼계수의 변화를 파악하기 위하여 정적인장시험을 실시하였다. 정적인장시험결과 모재 및 덮개판의 과대공 제작에 따라 미끄럼계수의 변화가 다소 발생하였으나 이를 정형화시키기에는 다소 무리가 따랐으며, 미끄럼강도는 표준공 제작시의 값과 과대공제작시의 값이 최대 26%의 차이를 나타내었다. 그러나 이는 설계미끄럼강도를 초과하기 때문에 사용하중하에서 연결부의 사용성에 미치는 영향이 미약하므로 강부재 제작시 부득이하게 발생할 수 있는 과대공에 따른 규정을 보다 유연하게 적용시킨다면 구조물의 설계 및 시공시 효율성과 경제성 증대의 효과가 기대된다고 판단되었다.

• Steel and Composite Structures
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• 제25권5호
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• pp.571-579
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• 2017

The grid structure with bolt-sphere joints is widely adopted by industrial plants with suspending crane. The alternating reciprocating action of the suspending crane will cause fatigue problems of the grid structure with bolt-sphere joints with respect to the rod, the cone, the sealing plate, the bolt ball and the high strength bolt; while the fatigue of the high strength bolt is the key issue of fatigue failure. Based on efficient and smooth loading equipment with the AMSLER fatigue testing machine, this paper conducted a constant amplitude fatigue test on 18 M20 and 14 M30 high strength bolts with 40Cr material, and obtained 19 valid failure points, 9 unspoiled points with more than 2 million cycles, and 4 abnormal failure points. In addition, it established the constant amplitude fatigue design method, ${[{\Delta}{\sigma}]_{{2{\times}10}}{^6=58.91MPa}$, and analyzed the stress concentration and the fatigue fracture of high strength bolts. It can be explained that the geometrical stress concentration of high-strength bolt caused by spiral burr is severe.

• 한국산학기술학회논문지
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• 제10권9호
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• pp.2402-2408
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• 2009

고장력볼트를 이용한 강부재의 체결에서 모재 및 덮개판의 과대공으로 인한 단면결손이 체결부에서 내하력의 저하가 우려되어 정적 인장시험을 실시하였다. 인장시험을 통하여 구해진 체결부의 파단시 최대하중을 단면결손율 및 설계강도와 비교하여 체결부의 내하력 변화를 파악하였다. 이에 따르면 단면결손율이 클수록 강도저하율이 컸으며 특히, 모재의 단면결손이 덮개판의 단면결손보다 강도저하에 대한 영향이 훨씬 큰 것으로 나타났다. 모재 및 덮개판을 과대공으로 제작한 고장력볼트 체결부는 표준공의 경우보다 내하성능이 다소 저하되었지만 파단시의 최대인장강도는 설계파단강도보다 15%이상 크게 나타났다. 본 연구에서는 과대공으로 제작된 고장력볼트 체결부에서 내하력저하에 미치는 영향이 미미하므로 강부재의 체결시공에 있어 과대공의 허용은 경제성과 효율성의 고취에 기여할 수 있을 것으로 판단되었다.

• 한국구조물진단유지관리공학회 논문집
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• 제6권4호
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• pp.119-127
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• 2002

본 연구의 목적은 강관구조물에서 고력볼트로 인장접합되는 플랜지 이음의 거동을 연구하는데 목적이 있다. 9개의 플랜지 이음 실험체의 실험을 수행하였으며, 실험시 고력볼트의 변형율과 이음부의 변형율 그리고 변위를 측정하였다. 고력볼트의 변형율, 플랜지 사이에서 발생하는 지레반력 그리고 강관과 플랜지 판의 응력분포를 연구하였다. 원형강관 플랜지 이음 설계에 사용되는 기준식을 비교 분석하였다.