광탄성 응력측정을 위한 투과형 원형편광기 제작 및 시험

백태현(Tae Hyun Baek),김명수(Myung Soo Kim) Korean Society for Precision Engineering 2004 한국정밀공학회지 Vol.21 No.3

다목적 투과형 편광기 시험 및 평가

백태현(Tae Hyun Baek),김명수(Myung Soo Kim),이춘태(Choon Tae Lee),김환(Whan Kim),박태근(Tae Guen Park) Korean Society for Precision Engineering 2005 한국정밀공학회지 Vol.22 No.1

인장하중을 받는 원공판의 광탄성 응력해석

이춘태(Choon Tae Lee),박태근(Tae Guen Park),정걸(Girl Jung),백태현(Tae Hyun Baek) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.3

In this paper, 8-step photoelastic phase shifting method was performed by using a multi-purpose polariscope to measure the fringe orders from the specimen made of Polycarbonate. The measurement results were compared with the results calculated by ABAQUS. Photoelastic measurements and FEM results are close comparable. The hybrid method that couples photoelastic data inputs and complex variable formulations involving conformal mapping analytical continuity is used to conduct the theoretic isochromatic fringe patter which were compared to the actual one.

Photoelastic evaluation of Maxillary Posterior Crossbite Appliance

Jang, Sung-Ho,Yoon, Young-Jooh,Kim, Kwang-Won 대한치과교정학회 2001 대한치과교정학회지 Vol.31 No.6

본 연구는 협측 이소맹출된 상악 제2대구치의 협측 반대교합을 개선하기 위해 사용되는 maxillary posterior crossbite appliance에 의해 상악 제2대구치의 치근단과 그주위의 치조골에 발생되는 응력분포를 알아보기 위해 광탄성법을 이용하여 분석하였다. 상악의 치조골을 재현하기 위해 PL-3형의 epoxy resin과 PL-3보다 경질인 레진치아를 사용하여 협측 이소맹출된 상악 제2대구치를 광탄성모형으로 재현하였다. 광탄성 모형상에 maxillary posterior crossbite appliance를 적용하고 힘을 가하기 전과후의 응력분포를 알아보기 위해 원형편광기를 사용하여 모형의 전후방에서 관찰하였다. 이상의 연구를 통해 얻어진 결과는 다음과 같다. 1. 상악 제2대구치의 구개면에 힘을 가한 경우, 협측과 구개측 치근첨에는 무늬차수 0.6차와 치경부에는 무늬차수 0.9차의 응력이 집중이 되어 나타났고 회전중심이 구개측 치근은 치근첨에, 협측 치근은 치근 1/4부위에 발생하였으며 이로 인해 제2대구치에 구개측으로의 비조절성 경사이동 및 회전력이 발생하였다. 2. 상악 제2대구치의 협측면에 힘을 가한 경우에는 구개면에 힘을 가한 경우 보다 협측과 구개측의 치근첨에 더 많은 무늬차수 2.2차의 응력이 발생하였다. 또한 치근하방의 치조골 부위에 응력의 발생과 함께 구개측 치근의 회전중심은 사라지고 협측 치근은 치근첨으로 이동하여 이로 인해 구개측으로의 조절성 경사이동 및 함입력이 발생하였다. 3. 상악 제2대구치의 협측이나 설측에 힘을 가한 경우, 고정원인 제1대구치는 치근첨부위에 소량의 응력이 발생하였고, 편측의 제2대구치에만 힘을 가한 경우보다 양측의 제2대구치에 동시에 힘을 가한 경우에서 더 많은 양의 응력이 제1대구치에 발생하였다. 이상의 결과는 협측 이소맹출된 상악 제2대구치의 구치부 협측 반대교합을 개선하기 위해 사용되는 maxillary posterior crossbite appliance를 적용할 때, 제1대구치의 고정원 상실을 최소화하기 위해서는 편측의 제2대구치를 먼저 개선시키고 그후 반대측 제2대구치의 개선을 도모하는 것이 바람직하다는 것을 의미한다. 또한 구개측면보다는 협측면에서 견인력을 가하여 제2대구치에 함입력과 구개측으로의 조절성 경사이동을 발생시키는 것이 구치의 정출 및 회전에 의해 야기될 수 있는 교합장애를 방지할 수 있으리라 사료된다. This study was undertaken to demonstrate the forces in the maxillary alveolar bone generated by the activation of the maxillary posterior crossbite appliance in the treatment of posterior buccal crossbite caused by buccal ectopic eruption of the maxillary second molar. A photoelastic model was fabricated using a photoelastic material (PL-3) to simulate alveolar bone and ivory-colored resin teeth. The model was observed throughout the anterior and posterior view in a circular polariscope and recorded photographically before and after activation of the maxillary posterior crossbite appliance. The following conclusions were reached from this investigation : 1. When the traction force was applied on the palatal surface of the second molar, stresses were concentrated at the buccal and palatal root apices and alveolar crest area. The axis of rotation of palatal root was at the root apex and that of the buccal root was at the root 1/4 area. In this result, palatal tipping and rotating force were generated. 2. When the traction force was applied on the buccal surface of the second molar, more stresses than loading on the palatal surface were observed in the palatal and buccal root apices. Furthermore, the heavier stresses creating an intrusive force and controlled tipping force were recorded below the buccal and palatal root apices below the palatal root surface. In addition, the axis of rotation of palatal root disappeared whereas the rotation axis of the buccal root moved to the root apex from the apical 1/4 area. 3. When the traction force was simultaneously applied on the maxillary right and left second molars, the stress intensity around the maxillary first molar root area was greater than the stress generated by the only buccal traction of the maxillary right or left second molar. As in above mentioned results, we should realize that force application on the palatal surface of second molars with the maxillary posterior crossbite appliance produced rotation of the second molar and palatal traction, which may cause occlusal interference. That is to say, we have to escape the rotation and uncontrolled tipping creating occlusal interference when correcting buccal posterior crossbite. For this purpose, we recommend buccal traction rather than palatal traction force on the second molar.

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.

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.

광탄성 위상이동법에 의한 사각형 구멍주위의 응력해석

이춘태(C. T. Lee),박태근(T. G. Park),정걸(J. Jung),헨리 팡가니반(H. Panganiban),정태진(T. J. Chung),백태현(T. H. Baek) 한국정밀공학회 2006 한국정밀공학회 학술발표대회 논문집 Vol.2006 No.5월

Photoelasticity is widely and conveniently used for whole field stress analysis. In this paper, 8-step photoelastic phase shifting method was performed by using a multi-purpose polariscope to measure the fringe orders along a specified line on the specimen containing a square hole. The material of the specimen is made of Polycarbonate. The measurement results by 8-step phase shifting method were comparable to those calculated by ABAQUS.

광탄성법을 이용한 인장판의 경사균열 응력확대계수 측정

백태현,이춘태,김영철 사단법인 인문사회과학기술융합학회 2015 예술인문사회융합멀티미디어논문지 Vol.5 No.2

This paper presents the measurement of stress intensity factors of inclined cracks by use of photoelasticity. The distributions of isochromatics near a crack tip of the specimen loaded by uniaxially tensile load are used for analysis. Accuracy and reliability is enhanced by twice multiplying and sharpening the measured isochromatics using digital image processing. Photoelastic results are compared with those obtained by finite element method. Good agreement between them shows that the photoelastic analysis is reliable. 본 논문에서는 중앙에 경사 균열이 있는 시편을 원형편광기에 설치하여 인장하중을 가한 후 나타나는 등색프린지로부터 디지털 영상처리기법을 사용하여 광탄성 프린지를 2배로 증식하여 세선처리한 후, 이로부터 응력확대계수를 측정하였다. 경사균열 시편으로부터 광탄성 법을 이용하여 응력확대계수를 구한 후 이론식으로 계산한 값과 비교하였다. 실험 결과는 이론값에 근접하였으며 광탄성 법으로 응력확대계수를 정밀하게 측정할 수 있는 가능성을 제시하였다.

테이퍼진 판을 이용한 광탄성 재료 응력프린지 상수 측정

백태현 한국기계기술학회 2015 한국기계기술학회지 Vol.17 No.3

In a photoelastic experiment, it is necessary to know the material stress fringe constant of the photoelastic specimen to determine the stresses from the measured isochromatic fringe orders. This type of compensator was proposed by the previous researchers. The recent image processing development of the stress pattern provide a means for making convenient compensator. The material stress fringe constant is determined using the distributions of isochromatic fringes in the wedge shaped plate under tensile load. The stress fringe constant measured with this method is applied to obtain the stress distribution along the central line on the tapered shank of the wedge-shaped plate. Photoelastic results using the measured material fringe constant are compared with FEM analysis. Two results are comparable, so it can be seen for the measured material fringe constant to be valid.

Chrome 변환을 이용한 CR 렌즈의 미세응력 시각화

김용근(Yong Geun Kim) 한국안광학회 2005 한국안광학회지 Vol.10 No.1