• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제30권3호
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• pp.175-180
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• 2004

In this study, three treatment options to replace two posterior missing teeth were investigated using three dimensional finite element analysis: two wide(${\phi}5.0mm$) implants(the experimental model I), two standard(${\phi}3.75mm$) implants(the experimental model II), and three standard(${\phi}3.75mm$) implants(the experimental model III). Two kinds of load case were applied ; 1) perpendicular on occlusal surface(axial load), parallel on occlusal surface(lateral load). 2) perpendicular on occlusal surface(3mm lateral to central point). The results obtained from this study were as follows; value of Von-mises stress (equivalent stress) was smallest in the two wide implant among the three experimental models. It was reported that the diameter is the efficient factor than osseointegrated surface area.

• 한국정밀공학회지
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• 제28권4호
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• pp.474-481
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• 2011

The purpose of this study was to investigate the effect of rigidity of post core systems on stress distribution by the finite element stress analysis method. Three-dimensional finite element models simulating an endodontically treated maxillary central incisor restored with a zirconia crown were prepared. Each model contained cortical bone, trabecular bone, periodontal ligament, 4mm apical root canal filling, and post-and-core. A 50N static occlusal load was applied to the palatal surface of the crown with a $60^{\circ}$ angle to the long axis of the tooth. And three parallel type post (zirconia, glass fiber and stainless steel) and two core (Paracore and Tetric ceram) materials were evaluated, respectively. The differences in stress transfer characteristics of the models were analyzed. von Mises stresses were chosen for presentation of results and maximum displacement and hydrostatic pressure were also calculated. For the Result of the research, the model applied glass fiber to post material has lowest von Mises stress and it is suitable for material of post core systems.

• Structural Engineering and Mechanics
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• 제43권4호
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• pp.439-448
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• 2012

This paper investigates the load sharing of double circular arc helical gears considering the influence of assembly errors. Based on a load sharing formulae, a three-dimensional finite element tooth contact analysis (TCA) is implemented with commercial software package ANSYS. The finite element grid for the double circular arc gear contact model is automatically generated by using the APDL (ANSYS Parameter Design Language) embedded in ANSYS. The realistic rotation of gears is achieved by using a coupling degree-of-freedom method. Numerical simulations are carried out to exemplify the proposed approach. The distribution of contact stress and bending stress under specific loading conditions are computed and compared with those obtained from Hertz contact theory and empirical formulae to demonstrate the efficiency of the proposed load sharing calculation formulae and TCA approach.

• Structural Engineering and Mechanics
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• 제69권1호
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• pp.69-75
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• 2019

The plates made of two materials joined to each other having the different coefficient of thermal expansions are frequently encountered in the industrial applications. The stress analysis of these members under the effect of high-temperature variation has great importance in design. In this study, the stress analysis of the experimental model developed for the problem considered here was performed by the method of photothermoelasticity. The thermal strains were formed by the mechanical way and these were fixed by the strain freezing method. For the stress measurements, the method of slicing is applied which provides three-dimensional stress analysis. The analytical solution in the literature was compared with the related stress distribution obtained from the model. Moreover, the axisymmetric finite element model developed for the problem was solved by ABAQUS and the results obtained here compared with those of the experimental model and the analytical solution. As a result of this study, this experimental method and numerical model can be used for these type of thermal stress problems which have not been comprehensively analyzed yet.

• 구강회복응용과학지
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• 제22권1호
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• pp.75-87
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• 2006

The purpose of this study was to investigate the effects of prostheses misfit, cantilever on the stress distribution in the implant components and surrounding bone using three dimensional finite element analysis. Two standard 3-dimensional finite element models were constructed: (1) 3 ITI implant supported, 3-unit fixed partial denture and (2) 3 ITI implant supported, 3-unit fixed partial denture with a distal cantilever. variations of the standard finite element models were made by placing a $100{\mu}m$ or $200{\mu}m$ gap between the fixture, the abutment and the crown on the second premolar and first molar. Total 14 models were constructed. In each model, 244 N of vertical load and 244 N of $30^{\circ}$ oblique load were placed on the distal marginal ridge of the distal molar. von Mises stresses were recorded and compared in the crowns, abutments, crestal compact bones, and trabecular bones. The results were obtained as follows: 1. In the ITI implant system, cement-retained prostheses showed comparatively low stress distributions on all the implant components and fixtures regardless of the misfit sizes under vertical loading. The stresses were increased twice under oblique loading especially in the prostheses with cantilever, but neither showed the effects of misfit size. 2. Under the oblique loading and posterior cantilever, the stresses were highly increased in the crestal bones around ITI implants, but effects of misfit were not shown. Although higher stresses were shown on the apical portion of trabecular bones, the effects by misfit were little and the stresses were increased by the posterior cantilever. 3. When the cement loss happened in the ITI implant supported FPD with misfit, the stresses were increased in the implant componets and supporting structures.

• 구강회복응용과학지
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• 제26권2호
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• pp.205-220
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• 2010

본 연구에서는 임플란트 디자인이 주입회전력과 주변 응력에 미치는 영향을 알아보고자 삼차원 유한 요소 분석을 이용하여 유효 응력과 모멘트 그리고 축력을 측정, 비교 조사하였다. 나사형 임플란트 매식체의 디자인을 4종의 평행형과 7종의 근첨형으로 구분하였고 하악골 소구치 부위에 식립한 것으로 가정하여 유한 요소 모델을 제작하였다. 각각의 임플란트가 식립될 때 주변부에 발생하는 응력을 분석하였으며 그 결과 근첨형 임플란트가 평행형 임플란트에 비해 높은 식립 회전력을 보여 초기 고정력이 우수할 것으로 예상되었으나 응력 분산 측면에 있어서는 효율성이 낮은 양상을 나타내었다. 근첨형 임플란트에 비해 평행형 임플란트가 나사산의 높이에 따른 영향을 크게 받는 것으로 나타났으며 근첨형 임플란트는 임플란트 몸체의 경사도가 증가함에 따라 높은 응력이 발생되는 것이 관찰되었다.

• 대한치과보철학회지
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• 제34권3호
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• pp.501-532
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• 1996

This study investigated the effects of cantilever length, location and load condition on stress distribution developed in the implants, prostheses and supporting tissues. The osseointegrated prostheses with two 10mm Branemark implants at 2nd premolar and 1st molar sites with cantilever extensions at 1st premolar, 2nd and 3rd molar sites were constructed. Under 100N, 200N of vertical and $45^{\circ}$ oblique loads at the cantilever pontics, stress distribution patterns and displacement were analyzed with three dimensional finite element method. The results were as follows : 1. The stress was concentrated at the joint of the cantilever pontic and implant superstructure, the neck of implant and the ridge crest near the cantilever But there was little load transfer to the lower supporting tissues of implants. 2. The implant near the cantilever was displaced inferiorly while the implant far from the cantilever was displaced superiorly. In horizontal direction the implants were displaced to the direction where the loads were applied, except the apexes of the implants. 3. In case of anterior cantilever, the stress and displacement were higher than the prosthesis connected with natural tooth. 4. The stress developed in the posterior cantilevered type was higher than in the anterior cantilevered type. The greastest stress was concentrated at the ridge crest near the posterior cantilever. 5. The longer the cantilever, the more the stress was developed and was concentrated at the joint of the cantilever pontic and implant superstructure. 6. Under oblique load, the stress was concentrated at the necks of implants and the ridge crests, but decreased at the joint of the cantilever pontic and implant superstructure than under vertical load.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1994년도 춘계학술대회
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• pp.131-135
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• 1994

In order to study the shape and dimensions of heart, the procedures to reconstruct a three dimensional left ventricular geometry from two dimensional echocardiographic images is studied including the coordinate transformation, curve fitting and interpolation utilizing three dimensional position registration arm. Nonlinear material property of the left ventricular myocardium was obtained by finite element method performed on the reconstructed geometry and optimization techniques which compare the computer predicted 3D deformation with the experimentally determined deformation. Afterwards using the obtained nonlinear material propertry the stress distribution related with oxyzen consumption rate was analyzed.

• 한국산학기술학회논문지
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• 제15권4호
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• pp.2414-2418
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• 2014

본 연구에서는 교량 통합 부대시설 모듈 구조 개발을 위하여 측면 탈 부착식 교량 방호울타리의 3차원 유한요소해석 및 구조 안정성 평가를 수행하였다. LS-DYNA 프로그램을 사용하여 연결 모듈의 격벽 간격 및 볼트 갯수 변화가 방호울타리 구조의 변위 및 응력에 미치는 영향을 상세 분석하였다. 본 연구에서는 LS-DYNA 프로그램을 사용한 유한요소해석은 콘크리트 바닥판에 삽입된 앵커볼트로 연결된 모듈 위에 설치된 방호울타리의 정적 거동과 구조 안전성을 분석하기 위하여 확장되었다. 수치해석은 6개의 매개변수에 대하여 방호울타리에 발생된 처짐 및 응력분포를 비교 분석하였으며 모두 구조적으로 안전성을 확보하는 것으로 나타났다.

• 대한치과보철학회지
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• 제31권3호
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• pp.351-384
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• 1993

Complete denture occlusion must be developed to function efficiently and with the least amount of trauma to the supporting tissues. For the preservation of supporting tissues, it is imperative to reduce to a minimum the functional stress induced by dentures. The magnitude of the horizontal component of functional stress contributed by various occlusal teeth forms has not been studied. This study was aimed to investigate the influence of different occlusal teeth forms on the mode of distribution of the stresses in the mandibular tissue, and the displacement of lower dentures during the variant functional movement of mandible for this study three dimensional finite element analysis was used. FEM models were created using commercial software Super Sap for IBM 32 bit computer. The model was composed of 3380 brick elements and 4346 nodes. The results were as follows. 1. The magnitude of stress was similar between two models in centric occlusion, in the case of anatomic model, the stress was concentrated on the buccal side of alveolar ridge beneath the bicuspids. 2. During the protrusive movement, the increasing of stress from the posterior to anterior part of mandible was seen in the case of anatomic model. 3. During the lateral movement, the stress of anatomic model was greater than that of nonanatomic model. 4. The stress of anatomic model was concentrated on the anterior region of residual ridge during the lateral movement. 5. In the case of anatomic model the anterior part of denture was displaced severely at the centric and lateral position, but the denture of nonanatomic model was displaced minutely at the protrusive and lateral position.