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  • Title/Summary/Keyword: Micro-Finite Element Analysis

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Stress Analysis of the Occlusal Force on the Mandibular First Premolar

  • Yoo, Oui-Sik;Chun, Keyoung-Jin;Yoo, Seung-Hyun
    • Journal of the Korean Society for Nondestructive Testing
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    • v.29 no.3
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    • pp.214-218
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    • 2009
  • The occlusal force of the tooth leads to loss of tooth tissue owing to attrition and abrasion, and may cause abfraction and pathological change of the dentin. Thus, we developed finite element models, examined them by applying ordinary occlusal force, and analyzed the stress distribution. Specimens used were mandibular first premolars from 15 Korean males and 13 females and were made into finite element models from medical images that were obtained using a Micro-CT. We have found that the irregular feature of the tooth is not only useful to masticating and pronouncing as well known, but it is also suitable for protecting inner tissue by dispersing stress and delivering proper pressure to periodontal tissue to continue a physiological action. Also, image analysis could let us know the factor that is the cause of a disorder due to stress concentration in the cervical line. These results are expected to support the field of dental treatment planning, operating procedure and clinical trial, and the advance of technical expertise to develop implants and dentures.

A Study of Surface Improvement for Automotive Part by Injection Mold of Electronic Heating (전류가열 사출금형에 의한 자동차 부품의 표면개선에 관한 연구)

  • Choi, Dong-Hyuk;Hwang, Hyun-Tae;Son, Dong-Il;Kim, Daeil
    • Journal of Surface Science and Engineering
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    • v.51 no.1
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    • pp.40-46
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    • 2018
  • The light-weight of the research and development materials is actively carried out by overseas automobile companies and technology development continues in Korea. For the sake of fuel efficiency, the development of lightweight technology by improving the manufacturing method has been very effective. Recently, to maximize the effects of light weight, automotive interior parts have been applied by the micro-cellular injection molding using supercritical fluids and we call the Mucell manufacturing. This technique causes a problem in the quality of the surface of the products, because the shooting cells are revealed as the surface layer of the products by forming micro cells at the center of the products during injection molding. To overcome these phenomenon, we increased the temperature of injection molding using joule heating until critical value. In this study, we have predicted the problem of Mucell injection molding through the finite element analysis as changed the temperature by joule heating. From the result of finite element analysis, we have determined the optimized process and made the injection mold included electric current heating system with Mucell manufacturing analyzed the surface characteristics of the injection product according to changing mold temperature.

Improvement of Filling Characteristics of Micro-Bumps in the Stencil Printing Process (스텐실 프린팅 공정에서 미세범프의 성형성 향상을 위한 연구)

  • Seo, W.S.;Min, B.W.;Park, K.;Lee, H.J.;Kim, J.B.
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.21 no.1
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    • pp.26-32
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    • 2012
  • In the present study, the stencil printing process using solder paste are numerically analyzed. The key design parameters in the stencil printing process are the printing conditions, stencil design, and solder paste properties. Among these parameters, the effects of printing conditions including the squeegee angle and squeegee pressure are investigated through finite element (FE) analysis. However, the FE analysis for the stencil printing process requires tremendous computational loads and time because this process carries micro-filling through thousands of micro-apertures in stencil. To overcome this difficulty in simulation, the present study proposes a two-step approach to sequentially perform the global domain analysis and the local domain analysis. That is, the pressure development under the squeegee are firstly calculated in the full analysis domain through the global analysis. The filling stage of the solder paste into a micro-aperture is then analyzed in the local analysis domain based on the results of the preceding global analysis.

Contact Stress Analysis of Shrink-fitted Specimen considering Micro-slip (미소슬립을 고려한 압입 시편의 접촉응력 해석)

  • Lee Dong-hyong;Goo Byeong-choon;Lee Chan-woo;Jung Heung-che
    • Proceedings of the KSR Conference
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    • 2004.06a
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    • pp.632-637
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    • 2004
  • In the shrink or press fitted shaft such as railway axle, fretting can occur by cyclic stress and micro-slippage due to local movement between the shaft and the hub. When the fretting occurs in the press fitted shaft, the fatigue strength remarkably decreases compared with that of without fretting. In this paper, the analysis of contact stresses in a press fitted shaft in contact with a hub was conducted by finite element method and the micro-slip according to the bending load was analyzed. It is found that the largest stress concentration and maximum slip amplitude of shrink fitted shaft are found at the edge of the interface and the distribution of contact stresses at the contact edge has largely influenced and coefficient of friction.

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The elastic and plastic behaviour of the micro-FE models for vertebral trabecular bones (척추 해면골에 대한 미세 유한요소모델의 탄성 및 소성특성에 관한 연구)

  • 우대곤;김한성;원예연;백명현;탁계래
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2003.06a
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    • pp.1320-1323
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    • 2003
  • In this study, the micro-FE analyses were carried out for the plastic behaviour of vertebral trabecular bones. Many researchers have investigated the elastic behaviour of trabecular bones by using the micro-finite element models based on the micro-CT images. However, there was no micro-FE model to account for the plastic behaviour of trabecular bones. Ulrich et at. reported that best results at coarser model were obtained when using 'compensated hexahedron models' with the same relative density. This study indicates that, for the elastic and plastic analysis, 'the compensated hexahedron FE model' is likely to be limited to about 63μm image resolution in the vertebra trabecular bones.

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Analysis and Design of a Forming Porcess for Combined Extrusion with Aluminum AIIoy 7075 (알루미늄 7075 복합압출재에 대한 공정해석 및 설계)

  • 김진복;변상규
    • Transactions of Materials Processing
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    • v.6 no.5
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    • pp.446-455
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    • 1997
  • A Combined extrusion operation consists of forward and backward extrusion forming and it is possible to make the process be simple by employing it. But the metal flow pattern induced by the operation is hard to analyze accurately because the flows are non-steady, which have at least two directions dependent upon each other. So engineers in the industrial factories had conducted the two extrusion operations separately. A new process was designed by the industrial expert for forming of an alu-minum preform using the combined extrusion operation. In this study, experiments and finite element analysis was carried out to determine the process parameters. Through the preliminary experiment, it was shown that warm forming condition was more desirable than cold or hot ones. And optimal shape of initial billet could be also determined. From the compatibility test, bonde-lube was chosen as the optimal lubricant and 200C as the material temperature by the inspection of micro-structure. The operation was simulated by the rigid-plastic finite element method to examine the metal flow. Disap-pearing of dead metal zone was observed as the punch fell down and desirable shape was obtained from the one operation. As a result of this study, 7 operations could be reduced and 225% of material saved.

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Nonlinear analysis of viscoelastic micro-composite beam with geometrical imperfection using FEM: MSGT electro-magneto-elastic bending, buckling and vibration solutions

  • Alimirzaei, S.;Mohammadimehr, M.;Tounsi, Abdelouahed
    • Structural Engineering and Mechanics
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    • v.71 no.5
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    • pp.485-502
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    • 2019
  • In this research, the nonlinear static, buckling and vibration analysis of viscoelastic micro-composite beam reinforced by various distributions of boron nitrid nanotube (BNNT) with initial geometrical imperfection by modified strain gradient theory (MSGT) using finite element method (FEM) are presented. The various distributions of BNNT are considered as UD, FG-V and FG-X and also, the extended rule of mixture is used to estimate the properties of micro-composite beam. The components of stress are dependent to mechanical, electrical and thermal terms and calculated using piezoelasticity theory. Then, the kinematic equations of micro-composite beam using the displacement fields are obtained. The governing equations of motion are derived using energy method and Hamilton's principle based on MSGT. Then, using FEM, these equations are solved. Finally the effects of different parameters such as initial geometrical imperfection, various distributions of nanotube, damping coefficient, piezoelectric constant, slenderness ratio, Winkler spring constant, Pasternak shear constant, various boundary conditions and three material length scale parameters on the behavior of nonlinear static, buckling and vibration of micro-composite beam are investigated. The results indicate that with an increase in the geometrical imperfection parameter, the stiffness of micro-composite beam increases and thus the non-dimensional nonlinear frequency of the micro structure reduces gradually.

Effect of bite force on orthodontic mini-implants in the molar region: Finite element analysis

  • Lee, Hyeon-Jung;Lee, Kyung-Sook;Kim, Min-Ji;Chun, Youn-Sic
    • The korean journal of orthodontics
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    • v.43 no.5
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    • pp.218-224
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    • 2013
  • Objective: To examine the effect of bite force on the displacement and stress distribution of orthodontic mini-implants (OMIs) in the molar region according to placement site, insertion angle, and loading direction. Methods: Five finite element models were created using micro-computed tomography (microCT) images of the maxilla and mandible. OMIs were placed at one maxillary and two mandibular positions: between the maxillary second premolar and first molar, between the mandibular second premolar and first molar, and between the mandibular first and second molars. The OMIs were inserted at angles of 45 and 90 to the buccal surface of the cortical bone. A bite force of 25 kg was applied to the 10 occlusal contact points of the second premolar, first molar, and second molar. The loading directions were 0, 5, and 10 to the long axis of the tooth. Results: With regard to placement site, the displacement and stress were greatest for the OMI placed between the mandibular first molar and second molar, and smallest for the OMI placed between the maxillary second premolar and first molar. In the mandibular molar region, the angled OMI showed slightly less displacement than the OMI placed at 90. The maximum Von Mises stress increased with the inclination of the loading direction. Conclusions: These results suggest that placement of OMIs between the second premolar and first molar at 45 to the cortical bone reduces the effect of bite force on OMIs.

Experimental and numerical studies of precast connection under progressive collapse scenario

  • Joshi, Digesh D.;Patel, Paresh V.;Rangwala, Husain M.;Patoliya, Bhautik G.
    • Advances in concrete construction
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    • v.9 no.3
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    • pp.235-248
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    • 2020
  • Progressive collapse in a structure occurs when load bearing members are failed and the adjoining structural elements cannot resist the redistributed forces and fails subsequently, that leads to complete collapse of structure. Recently, construction using precast concrete technology is adopted increasingly because it offers many advantages like faster construction, less requirement of skilled labours at site, reduced formwork and scaffolding, massive production with reduced amount of construction waste, better quality and better surface finishing as compared to conventional reinforced concrete construction. Connections are the critical elements for any precast structure, because in past, major collapse of precast structure took place because of connection failure. In this study, behavior of four different precast wet connections with U shaped reinforcement bars provided at different locations is evaluated. Reduced 1/3rd scale precast beam column assemblies having two span beam and three columns with removed middle column are constructed and examined by performing experiments. The response of precast connections is compared with monolithic connection, under column removal scenario. The connection region of test specimens are filled by cast-in-place micro concrete with and without polypropylene fibers. Performance of specimen is evaluated on the basis of ultimate load carrying capacity, maximum deflection at the location of removed middle column, crack formation and failure propagation. Further, Finite element (FE) analysis is carried out for validation of experimental studies and understanding the performance of structural components. Monolithic and precast beam column assemblies are modeled using non-linear Finite Element (FE) analysis based software ABAQUS. Actual experimental conditions are simulated using appropriate boundary and loading conditions. Finite Element simulation results in terms of load versus deflection are compared with that of experimental study. The nonlinear FE analysis results shows good agreement with experimental results.

Application of OMA on the bench-scale earthquake simulator using micro tremor data

  • Kasimzade, Azer A.;Tuhta, Sertac
    • Structural Engineering and Mechanics
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    • v.61 no.2
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    • pp.267-274
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    • 2017
  • In this study was investigated of possibility using the recorded micro tremor data on ground level as ambient vibration input excitation data for investigation and application Operational Modal Analysis (OMA) on the bench-scale earthquake simulator (The Quanser Shake Table) for model steel structures. As known OMA methods (such as EFDD, SSI and so on) are supposed to deal with the ambient responses. For this purpose, analytical and experimental modal analysis of a model steel structure for dynamic characteristics was evaluated. 3D Finite element model of the building was evaluated for the model steel structure based on the design drawing. Ambient excitation was provided by shake table from the recorded micro tremor ambient vibration data on ground level. Enhanced Frequency Domain Decomposition is used for the output only modal identification. From this study, best correlation is found between mode shapes. Natural frequencies and analytical frequencies in average (only) 2.8% are differences.