하악 구치부에서 임플랜트 배열방식에 따른 임플랜트지지 고정성 국소의치의 광탄성 응력 분석

조혜원,김난영,김유리,Cho Hye-Won,Kim Nan-Young,Kim Yu-Lee 대한치과보철학회 2005 대한치과보철학회지 Vol.43 No.1

Statement of problem. More than 70% of patients who need the implant supported restoration are parially edentulous. The principles of design for implant supported fixed partial denture in mandibular posterior region are many and varied. Jurisdiction for their use is usually based on clinical evaluation. There are several areas or interest regarding the design of implant supported fixed partial denture in mandibular posterior region. 1) Straight and tripod configuration in implant placement, 2) Two restoration types such as individualized and splinted restorations. Purpose. The purpose of this study was to compare the amount and distribution of stress around the implant fixtures placed in the mandibular posterior region with two different arrangements and to evaluate the effects of splinting using the photoelastic stress analysis. Material & methods. 1) Production of study model: Mandibular partially edentulous model was waxed-up and duplicated with silicone and two models were poured in stone. 2) Fixture installation and photoelastic model construction: Using surveyor(Ney, USh), 3 fixtures(two 4.0 $\times$13 mm, one 5.0$\times$10 mm, Lifecore, USA) were insta)led in straight & tripod configurations. Silicone molds were made and poured in photoelastic resin (PL-2. Measurements group, USA). 3) Prostheses construction: Four 3-unit bridges (Type III gold alloy, Dongmyung co., Korea) were produced with nonhexed and hexed UCLA abutments and fitted with conventional methods. The abutments were tightened with 30 Ncm torque and the static loads were applied at 12 points of the occlusal surface. 4) Photoelastic stress analysis : The polarizer analyzer system with digital camera(S-2 Pro, Fujifilm, Japan) was used to take the photoelastic fringes and analysed using computer analysis program. Results. Solitary hexed UCLA restoration developed different stress patterns between two implant arrangement configurations, but there were no stress transfer to adjacent implants from the loaded implant in both configurations. However splinted restorations showed lesser amount of stresses in the loaded implants and showed stress transfer to adjacent implants in both configurations. Solitary hexed UCLA restoration with tripod configuration developed higher stresses in anterior and middle implants under loading than implants with straight configurations. Splintied 3 unit fixed partial dentures with tripod configuration showed higher stress development in posterior implant under loading but there were no obvious differences between two configurations. Conclusions. The tripod configuration of implant arrangement didn't show any advantages over the straight configuration. Splinting of 3 unit bridges with nonhexed UCLA abutments showed less stress development around the fixtures. Solitary hexed UCLA restoration developed tilting of implant fixture under offset loads.

등색프린지 데이터를 이용한 인장하중 판재 중앙 균열선단 주위의 하이브리드 광탄성 응력장 해석

백태현(Tae Hyun Baek),첸레이(Lei Chen) 대한기계학회 2007 大韓機械學會論文集A Vol.31 No.12

An experimental test is presented for photoelastic stress analysis around a crack tip in tensile loaded plate. The hybrid method coupling photoelastsic fringe inputs calculated by finite element method and complex variable formulations involving conformal mappings and analytical continuity is used to calculate full-field stress around the crack tip in uniaxially loaded, finite width tensile plate. In order to accurately compare calculated fringes with experimental ones, both actual and regenerated photoelastic fringe patterns are two times multiplied and sharpened by digital image processing. Regenerated fringes by hybrid method are quite comparable to actual fringes. The experimental results indicate that Mode I stress intensity factor analyzed by the hybrid method are accurate within three percent compared with ones obtained by empirical equation and finite element analysis.

원형구멍이 있는 인장시편에서 광탄성위상이동법을 이용한 하이브리드 응력해석

백태현(Tae Hyun Baek),이춘태(Choon Tae Lee),박태근(Tae Geun Park) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.11

It is difficult to measure the stresses around a hole in loaded plate due to stress concentration. In this paper, a hybrid experimental-numerical method is presented for this problem. Measured fringes orders obtained form photoelastic phase-shifting method provide the input fringes on straight line, and these measured data are used for hybrid analysis. Different numbers of terms in a power-series representation of the complex type stress function are tested in order to improve the analytic precision. The fringes generated by hybrid method are highly comparable with the actual fringes. The result shows that this approach is effective and promising to do full-field stress analysis because the isochromatic data along the straight lines can be conveniently measured by use of photoelastic phase-shifting experiment.

하악 임플란트 overdenture에서 anchorage system이 하중전달에 미치는 영향

김진열,전영찬,정창모,Kim Jin-Yeol,Jeon Young-Chan,Jeong Chang-Mo 대한치과보철학회 2002 대한치과보철학회지 Vol.40 No.5

Load transfer of implant overdenture varies depending on anchorage systems that are the design of the superstructure and substructure and the choice of attachment. Overload by using improper anchorage system not only will cause fracture of the framework or screw but also may cause failure of osseointegration. Choosing anchorage system in making prosthesis, therefore, can be considered to be one of the most important factors that affect long-term success of implant treatment. In this study, in order to determine the effect of anchorage systems on load transfer in mandibular implant overdenture in which 4 implants were placed in the interforaminal region, patterns of stress distribution in implant supporting bone in case of unilateral vertical loading on mandibular left first molar were compared each other according to various types of anchorage system using three-dimensional photoelastic stress analysis. The five photoelastic overdenture models utilizing Hader bar without cantilever using clips(type 1), cantilevered Hader bar using clips(type 2), cantilevered Hader bar with milled surface using clips(type 3), cantilevered milled-bar using swivel-latchs and frictional pins(type 4), and Hader bar using clip and ERA attachments(type 5), and one cantilevered fixed-detachable prosthesis(type 6) model as control were fabricated. The following conclusions were drawn within the limitations of this study, 1. In all experimental models. the highest stress was concentrated on the most distal implant supporting bone on loaded side. 2. Maximum fringe orders on ipsilateral distal implant supporting bone in a ascending order is as follows: type 5, type 1, type 4, type 2 and type 3, and type 6. 3. Regardless of anchorage systems. more or less stresses were generated on the residual ridge under distal extension base of all overdenture models. To summarize the above mentioned results, in case of the patients with unfavorable biomechanical conditions such as not sufficient number of supporting implants, short length of the implant and unfavorable antero-posterior spread. selecting resilient type attachment or minimizing distal cantilever bar is considered to be appropriate methods to prevent overloading on implants by reducing cantilever effect and gaining more support from the distal residual ridge.

위상이동 광탄성법과 멱급수형 응력함수를 이용한 인장시편 중앙 균열선단 주위 응력장 해석

백태현(Tae Hyun Baek) 한국비파괴검사학회 2009 한국비파괴검사학회지 Vol.29 No.1

본 연구에서는 균열선단 주위의 응력장을 균열선단으로부터 멀리 떨어진 직선상에서 위상이동 광탄성법과 멱급수형 등각사상 맵핑함수를 이용하여 해석하였다. 해석된 광탄성 응력장을 실제의 광탄성프린지와 비교하였다. 정성적인 비교가 용이하도록 디지털 영상처리에 의해 등색프린지 패턴을 2배로 증식시키고, 증식된 프린지를 다시 세선 처리하여 서로 비교하였다. 정량적인 분석을 위하여 각각의 광탄성 측정 데이터와 계산된 프린지에 대한 퍼센트 오차와 멱급수형 응력함수의 항의 수에 따른 퍼센트 오차에 대한 표준편차를 비교하였다. 응력함수의 항의 수를 변화시켰을 때 표준편차를 계산하였다. 해석 결과 모드Ⅰ 응력확대계수는 유한요소법과 경험식으로 계산한 값과 2% 이내로 근접하였다. This paper presents stress distribution around a central crack tip in a tensile plate using phase-shifting photoelasticity and a power series stress function. Isochromatic data along the straight lines far from the crack tip were obtained by phase shifting photoelasticity and were used as input data of the hybrid experimental analysis. By using the complex-type power series stress equations, the photoelastic stress distribution fields in the vicinity of the crack and the mode Ⅰ stress intensity factor were obtained. With the help of image processing software, accuracy and reliability was enhanced by twice multiplying and sharpening the measured isochromatics. Actual and reconstructed fringes were compared qualitatively. For quantitative comparison, percentage errors and standard deviations of the percentage errors were calculated for all measured input data by varying the number of terms in the stress function. The experimental results agreed with those predicted by finite element analysis and empirical equation within 2 percent error.

광탄성 위상이동법을 이용한 인장판 경사균열 선단주위의 프린지 해석

리웨이정(Weizheng Li),백태현(Tae Hyun Baek),홍동표(Dong Pyo Hong),이병희(Byung Hee Lee),서진(Jin Seo) 한국비파괴검사학회 2012 한국비파괴검사학회지 Vol.32 No.1

광탄성법은 실험역학에서 응력 또는 변형률을 해석하기 위한 여러 실험방법 중의 하나이며, 다양한 종류의 구조물의 응력 분포를 실험적으로 결정하는 기법이다. 광탄성법은 광탄성 영상의 등색 프린지와 등경 프린지로부터 광탄성 시편에 나타나는 전체의 응력장 분포를 정밀하게 측정할 수 있다. 본 논문에서는 여러 가지 광탄성 기법중 8단계 위상이동법(8-step phase-shifting method)에 관한 이론을 살펴보고, 경사균열이 있는 평판 시편에 인장을 가하여 나타난 광탄성 프린지로부터 경사균열 선단주위의 응력분포를 8단계 위상이동법으로 결정한 후, 이들 결과를 유한요소법(FEM)에 의한 결과와 비교하였다. 8단계 위상이동법을 이용한 실험에 의해 측정된 프린지 차수는 유한요소법에 의한 계산된 프린지 차수값에 근접하였다. Photoelasticity is a technique of experimental methods and has been widely used in various domains of engineering to determine the stress distribution of structures. Without complicated mathematical formulation, this technique can conveniently provide a fairly accurate whole-field stress analysis for a mechanical structure. Here, stress distribution around an inclined crack tip of finite-width plate is studied by 8-step phase-shifting method. This method is a kind of photoelastic phase-shifting techniques and can be used for the determination of the phase values of isochromatics and isoclinics. According to stress-optic law, the stress distribution could be obtained from fringe patterns. The results obtained by polariscope arrangement combined with 8-step method and ABAQUS FEM simulations are compared with each other. Good agreement between them shows that 8-step phase-shifting method is reliable and can be used for determination of stress by experiment.

유한요소 변위값을 이용한 인장하중 판재 균열선단 주위의 응력분포 해석

백태현(Tae Hyun Baek) Korean Society for Precision Engineering 2008 한국정밀공학회지 Vol.25 No.10

Due to the complexity of the engineering problems, it is difficult to obtain directly the stress field around the crack tip by theoretical derivation. In this paper, the hybrid method is employed to calculate full-field stress around the crack tip in uni-axially loaded finite width tensile plate, using the displacement data of given points calculated by finite element method as input data. The method uses complex variable formulations involving conformal mappings and analytical continuity. In order to accurately compare calculated fringes with experimental ones, both actual and reconstructed photoelastic fringe patterns are two times multiplied and sharpened by digital image processing. Reconstructed fringes by hybrid method are quite comparable to actual fringes. The experimental results indicate that Mode I stress intensity factor analyzed by the hybrid method are accurate within a few percent compared with ones obtained by empirical equation and finite element analysis.

광탄성법을 이용한 곡선보 평판의 응력분포 해석

김수일,김명수,백태현 韓國非破壞檢査學會 1999 한국비파괴검사학회지 Vol.19 No.3

광탄성법을 이용하여 인장하중을 받는 곡선보의 중앙에서 하중축과 직교하는 일직선상에 축방향 응력성분을 측정하였다. 광탄성 데이터의 정밀 측정을 위하여 영상처리 시스템을 이용, 원래의 프린지를 명시야 배열과 암시야 배열의 등색선프린지로부터 2배로 증식시키고 세선처리를 하였다. 세선처리된 광탄성 영상으로부터 1/4차수(N=0, 1/4, 2/4, 3/4, 1, 5/4…)마다 프린지 차수를 읽을 수 있으므로 정확한 위치에서 정량적인 측정이 가능하다. 광탄성 실험에서 곡선보의 인장 하중을 3종류로 변화하였을 때 이론식에 의한 응력분포와 일치하는 경향을 나타냈으나, 광탄성법에 의한 측정결과는 이론값과 8%이내의 차이가 나타났다. 이러한 원인은 광탄성 시험편 가공시 하중축과 치수가 이론식에 적용된 조건과 다소 상이한 것으로 판단되머, 정밀하게 가공된 시험편을 사용하여 측정할 경우 실험에 의한 오차는 감소될 것으로 추정된다. 이 실험으로부터 광탄성법에 의한 응력측정시 프린지 증식 및 세선처리 기법을 적용할 경우 정밀한 응력측정이 가능함을 확인할 수 있었다. This paper describes the stress analysis of a curved beam by using photoelasticity. In order to measure accurate isochromatic fringe orders at certain locations. fringes are doubled and sharpened by digital image processing. After fringe multiplication and sharpening, fringe orders can be read as a quarter order interval(N=p. 1/4, 2/4, 3/4,…). The results obtained from photoelastic experiment are compared with those calculated by using theory. Two results are agreed well even though there are some scatter bands with maximum 8 percent for the results of photoelastic measurements and theoretical calculation. Difference may be occurred due to the slight misalignment of the direction to which axial load is applied in photoelastic experiment. It is confirmed that accurate measurement of stress distribution can be possible by using the techniques of fringe multiplication and sharpening in photoelasticity.

광탄성위상이동법에 의한 인장시편 타원형 구멍주위 하이브리드 응력해석

이춘태(Choon Tae Lee),박태근(Tae Geun Park),양민복(Min Bok Yang),백태현(Tae Hyun Baek) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.9

A hybrid experimental-numerical method is presented for determining the stresses around an elliptical hole in a finite-width, tensile loaded plate. Measured fringe orders along straight lines provide the input information on the external boundary of the hybrid element. In order to see the effects of varying stress field, different numbers of terms in a power-series representation of the complex type stress function are tested. Actual and reconstructed fringes are compared. The hybrid results are highly comparable with those predicted by FEA. The result shows that this approach is effective and promising because isochromatic data along the straight lines in photoelasticity can be conveniently measured by use of phase shifting photoelasticity.

광탄성과 유한요소법을 이용한 타원형 구멍주위의 하이브리드 응력장 해석

박태근(Tae Geun Park),헨리 팡가니반(Henry Panganiban),정태진(Tae Jin Chung),백태현(Tae Hyun Baek) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.3

A hybrid experimental-numerical method is presented for determining the stresses around a elliptical hole in a finite-width, tensile loaded plate. Calculated fringe orders obtained from FEA provide the input information on the external boundary of the hybrid element. Experimental input fringes on straight line are used for hybrid analysis. In orderto see the effects of varying stress field, different numbers of terms in a power-series representation of the complex type stress function are tested. Actual and reconstructed fringes are compared. The hybrid results are highly comparable with those predicted by FEA. The result shows that this approach is effective and promising because isochromatic data along the straight lines in photoelasticity can be conveniently measured by use of phase shifting hotoelasticity.