• Title, Summary, Keyword: finite element models

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Finite Element Modeling and Mechanical Analysis of Orthodontics (치아교정의 역학적 해석을 의한 유한요소 모델링 및 치아의 거동해석)

  • Heo, Gyeong-Heon;Cha, Gyeong-Seok;Ju, Jin-Won
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.24 no.4
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    • pp.907-915
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    • 2000
  • The movement of teeth and initial stress associated with the treatment of orthodontics have been successfully studied using the finite element method. To reduce the effort in preprocessing of finite element analysis, we developed two types of three-dimensional finite element models based on the standard teeth model. Individual malocclusions were incorporated in the finite element The movement of teeth and initial stress associated with the treatment of orthodontics have been successfully studied using the finite element method. To reduce the effort in preprocessing of finite element analysis, we developed two types of three-dimensional finite element models based on the standard teeth model. Individual malocclusions were incorporated in the finite element models by considering the measuring factors such as angulation, crown inclination, rotation and translations. The finite element analysis for the wire activation with a T-loop arch wire was carried out. Mechanical behavior on the movement and the initial stress for the malocclusion finite element model was shown to agree with the objectives of the actual treatment. Finite element models and procedures of analysis developed in this study would be suitably utilized for the design of initial shape of the wire and determination of activation displacements.

Choice of Thresholding Technique in Micro-CT Images of Trabecular Bone Does Not Influence the Prediction of Bone Volume Fraction and Apparent Modulus

  • Kim, Chi-Hyun;Kim, Byung-Gwan;Guo, X. Edward
    • Journal of Biomedical Engineering Research
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    • v.28 no.2
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    • pp.174-177
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    • 2007
  • Trabecular bone can be accurately represented using image-based finite element modeling and analysis of these bone models is widely used to predict their mechanical properties. However, the choice of thresholding technique, a necessary step in converting grayscale images to finite element models which can thus significantly influence the structure of the resulting finite element model, is often overlooked. Therefore, we investigated the effects of thresholding techniques on micro-computed tomography (micro-CT) based finite element models of trabecular bone. Three types of thresholding techniques were applied to micro-CT images of trabecular bone which resulted in three unique finite element models for each specimen. Bone volume fractions and apparent moduli were predicted for each model and compared to experimental results. Our findings suggest that predictions of apparent properties agree well with experimental measurements regardless of the choice of thresholding technique in micro CT images of trabecular bone.

Three-dimensional finite element analysis of implant-supported crown in fibula bone model

  • Park, Young-Seok;Kwon, Ho-Beom
    • The Journal of Advanced Prosthodontics
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    • v.5 no.3
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    • pp.326-332
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    • 2013
  • PURPOSE. The purpose of this study was to compare stress distributions of implant-supported crown placed in fibula bone model with those in intact mandible model using three-dimensional finite element analysis. MATERIALS AND METHODS. Two three-dimensional finite element models were created to analyze biomechanical behaviors of implant-supported crowns placed in intact mandible and fibula model. The finite element models were generated from patient's computed tomography data. The model for grafted fibula was composed of fibula block, dental implant system, and implant-supported crown. In the mandible model, same components with identical geometries with the fibula model were used except that the mandible replaced the fibula. Vertical and oblique loadings were applied on the crowns. The highest von Mises stresses were investigated and stress distributions of the two models were analyzed. RESULTS. Overall stress distributions in the two models were similar. The highest von Mises stress values were higher in the mandible model than in the fibula model. In the individual prosthodontic components there was no prominent difference between models. The stress concentrations occurred in cortical bones in both models and the effect of bicortical anchorage could be found in the fibula model. CONCLUSION. Using finite element analysis it was shown that the implant-supported crown placed in free fibula graft might function successfully in terms of biomechanical behavior.

Sensitivity analysis for finite element modeling of humeral bone and cartilage

  • Bola, Ana M.;Ramos, A.;Simoes, J.A
    • Biomaterials and Biomechanics in Bioengineering
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    • v.3 no.2
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    • pp.71-84
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    • 2016
  • The finite element method is wide used in simulation in the biomechanical structures, but a lack of studies concerning finite element mesh quality in biomechanics is a reality. The present study intends to analyze the importance of the mesh quality in the finite element model results from humeral structure. A sensitivity analysis of finite element models (FEM) is presented for the humeral bone and cartilage structures. The geometry of bone and cartilage was acquired from CT scan and geometry reconstructed. The study includes 54 models from same bone geometry, with different mesh densities, constructed with tetrahedral linear elements. A finite element simulation representing the glenohumeral-joint reaction force applied on the humerus during $90^{\circ}$ abduction, with external load as the critical condition. Results from the finite element models suggest a mesh with 1.5 mm, 0.8 mm and 0.6 mm as suitable mesh sizes for cortical bone, trabecular bone and humeral cartilage, respectively. Relatively to the higher minimum principal strains are located at the proximal humerus diaphysis, and its highest value is found at the trabecular bone neck. The present study indicates the minimum mesh size in the finite element analyses in humeral structure. The cortical and trabecular bone, as well as cartilage, may not be correctly represented by meshes of the same size. The strain results presented the critical regions during the $90^{\circ}$ abduction.

Issues in Static FE Analysis of Reinforced Concrete Panels subjected to Biaxial Tensile Loads (이축인장을 받는 철근콘크리트 패널의 정적 유한요소해석에서의 논점)

  • 이상진;이홍표;이영정
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.569-576
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    • 2003
  • Fundamental issues in static finite element analysis of reinforced concrete panel subjected to biaxial tensile loads are discussed. This paper is trying to bring our attention to the appropriate use of concrete material models such as cracking criteria, tension stiffening model and the steel models which are basically used in the nonlinear finite element analysis of reinforced concrete panels. We mainly investigate the sensitivity of available material models and finite element technologies to the finite element analysis result using our recent reinforced concrete panel experiment result. Throughout this study, we found that the judicious use of the material models and finite element technologies with the sound understanding of structural characteristics can only guarantee the accurate prediction of panel behaviour.

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Experimental analysis on FEM definition of backfill-rectangular tank-fluid system

  • Cakir, Tufan;Livaoglu, Ramazan
    • Geomechanics and Engineering
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    • v.5 no.2
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    • pp.165-185
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    • 2013
  • In the present study, the numerical and experimental investigations were performed on the backfill- exterior wall-fluid interaction systems in case of empty and full tanks. For this, firstly, the non-linear three dimensional (3D) finite element models were developed considering both backfill-wall and fluid-wall interactions, and modal analyses for these systems were carried out in order to acquire modal frequencies and mode shapes by means of ANSYS finite element structural analysis program. Secondly, a series of field tests were fulfilled to define their modal characteristics and to compare the results from proposed approximation in the selected structures. Finally, comparing the theoretical predictions from the finite element models to results from experimental measurements, a close agreement was found between theory and experiment. Thus, it can be easily stated that experimental verifications provide strong support for the finite element models and the proposed procedures themselves are the meritorious approximations to the real problem, and this makes the models appealing for use in further investigations.

A Study on Orbital Forming Analysis of Automotive Hub Bearing using the Explicit Finite Element Method (외연적 유한요소법을 이용한 자동차 Hub Bearing의 Orbital Forming해석에 관한 연구)

  • Cho, Hyun-Jik;Koo, Jeong-Seo;Bae, Won-Rak;Lim, Jong-Soon
    • Transactions of the Korean Society of Automotive Engineers
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    • v.16 no.1
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    • pp.29-36
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    • 2008
  • In this paper, the orbital forming analysis of an automotive hub bearing was studied to predict forming performances using the explicit finite element method. To find an efficient solution technique for the orbital forming, axisymmetric finite element models and 3D solid element models were solved and numerically compared. The time scaling and mass scaling techniques were introduced to reduce the excessive computational time caused by small element size in case of the explicit finite element method. It was found from the numerical simulations on the orbital forming that the axisymmetric element models showed the similar results to the 3D solid element models in forming loads whereas the deformations at the inner race of bearing were quite different. Finally the strains at the inner race of bearing and the forming forces to the peen were measured for the same product of the numerical model by test, and were compared with the 3D solid element results. It was founded that the test results were in good agreements with the numerical ones.

Static Analysis of Two Dimensional Curbed Beam Structure by Finite Element-Transfer Stiffness Coefficent Method (유한요소-전달강성계수법에 의한 2차원 곡선 보 구조물의 정적해석)

  • Choi, Myung-Soo
    • Journal of Power System Engineering
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    • v.21 no.6
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    • pp.40-45
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    • 2017
  • The objective of this study is the finite element-transfer stiffness coefficient method, which is the combination of the modeling technique of finite element method and the transfer technique of transfer stiffness coefficient method, is applied in the static analyses of two dimensional curved beam structures. To confirm the effectiveness of the applied method, two computational models are selected and analyzed by using finite element method, finite element-transfer stiffness coefficient method and exact solution. The computational results of the static analyses for two computational models using finite element-transfer stiffness coefficient method are equal to those using finite element method. When the element partition number of curved beam structure is increased, the computational results of the static analyses using both methods approach the exact solution. We confirmed that the finite element-transfer stiffness coefficient method is superior to finite element method when the number of the curved beam elements is increased from the viewpoints of the computational speed and the utility of computer memory.

Finite element analysis of shear-critical reinforced concrete walls

  • Kazaz, Ilker
    • Computers and Concrete
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    • v.8 no.2
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    • pp.143-162
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    • 2011
  • Advanced material models for concrete are not widely available in general purpose finite element codes. Parameters to define them complicate the implementation because they are case sensitive. In addition to this, their validity under severe shear condition has not been verified. In this article, simple engineering plasticity material models available in a commercial finite element code are used to demonstrate that complicated shear behavior can be calculated with reasonable accuracy. For this purpose dynamic response of a squat shear wall that had been tested on a shaking table as part of an experimental program conducted in Japan is analyzed. Both the finite element and material aspects of the modeling are examined. A corrective artifice for general engineering plasticity models to account for shear effects in concrete is developed. The results of modifications in modeling the concrete in compression are evaluated and compared with experimental response quantities.

Analysis of composite plates using various plate theories -Part 2: Finite element model and numerical results

  • Bose, P.;Reddy, J.N.
    • Structural Engineering and Mechanics
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    • v.6 no.7
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    • pp.727-746
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    • 1998
  • Finite element models and numerical results are presented for bending and natural vibration using the unified third-order plate theory developed in Part 1 of this paper. The unified third-order theory contains the classical, first-order, and other third-order plate theories as special cases. Analytical solutions are developed using the Navier and L$\acute{e}$vy solution procedures (see Part 1 of the paper). Displacement finite element models of the unified third-order theory are developed herein. The finite element models are based on $C^0$ interpolation of the inplane displacements and rotation functions and $C^1$ interpolation of the transverse deflection. Numerical results of bending and natural vibration are presented to evaluate the accuracy of various plate theories.