• 전산구조공학
• /
• 제10권3호
• /
• pp.145-155
• /
• 1997

본 연구에서는 ANSYS와 ABAQUS 상용 유한요소 코드를 이용하여 궤도차량의 정적.동적 해석을 충격하중과 주행하중에 대해서 수행하였다. 궤도차량이 충격하중을 받을 때 최대 동적 Von Mises응력은 상판의 빔보강재와 레이스링사이에서 발생하였으며 응력수준은 390-450MPa이다. 정하중에 대한 동하중수 1.6을 고려했을 경우 동적 해석과 동적하중계수가 포함된 정하중 해석은 유사한 결과를 보이고 있다. 과도응력은 주로 레이싱링 주위에서 발생하고 있다. 주행하중의 경우 최대응력은 로드휠 유기압 현가장치 #1번에서 450MPa정도이며, 정적해석과 비선형 해석의 결과가 유사하다.

• 대한치과교정학회지
• /
• 제41권6호
• /
• pp.384-398
• /
• 2011

교정용 미니스크류를 이용하여 하악 전치의 함입이 가능하다고 알려져 있으나 분절의 크기에 따른 예측가능한 이동 양상에 대하여 보고된 바는 미미하다. 본 연구에서는 하악 4전치와 6전치 분절 모델에서 미니스크류와 훅의 위치를 달리하여 함입력을 적용하였을 때 응력분포와 초기 변위 양상을 분석하고자 하악 전치와 치주인대, 치조골에 대한 3차원 유한요소 모델을 제작하여 미니스크류 및 호선상 훅의 위치에 의해 결정되는 힘 벡터에 따른 치아의 3차원 각 평면에서의 변위량 및 von Mises 응력분포 양상을 비교하였다. 하악 4전치 분절에서는 함입력의 위치에 무관하게 공히 치관의 전방 경사가 발생하였으며 측절치 원심의 미니스크류와 후하방 힘을 가한 경우 경사 정도가 최소인 것으로 나타났다. 6전치 분절의 함입 시 견치 전방에 위치한 미니스크류에 의해 역시 상당한 치관의 전방 경사 및 순측치경부 치근막에 von Mises stress가 집중되었으며 견치 후방에 위치한 미니스크류와 중절치-측절치 간 훅에 의한 힘에 의해 순수한 함입에 가까운 치아 변위 및 치근막 전체에 균일한 von Mises stress의 분포가 관찰되었다. 이러한 결과를 토대로 하악 전치의 함입이 요구되는 과개교합 증례에서 견치 원심측의 미니스크류와 중절치-측절치 간 훅을 이용한 후하방 힘에 의해 예측가능하게 하악 6전치의 순수한 함입을 유도할 수 있을 것으로 생각된다.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• 제30권4호
• /
• pp.345-352
• /
• 2008

Purpose: This study was performed to evaluate the stress distribution in the bone and the displacement distribution of the miniscrew under orthopedic force with two different types of miniplate design as skeletal anchorage for orthopedic treatment. Materials and methods: Finite element models were made for 6-hole miniplate (0.8mm in thickness), which were designed in two different shapes-one is curvilinear shaped (C plate, Jeil Medical Co., Korea) and another, Y shaped (Y plate), fixed with 3 pieces of miniscrew 2mm-diameter and 6mm-long respectively. A traction force of 4 N was applied in $0^{\circ}$, $30^{\circ}$ and $60^{\circ}$ to imaginary axis connecting two unfixed distalmost holes of the miniplate. Results: The maximum von Mises stress in the bone was much greater in the cortical portion rather than in the cancellous portion. C plate showed greater maximum von Mises stress in the cortical bone than Y plate. The maximum displacement of the miniscrew was greater in C plate than Y plate. The more increased the angle of the applied orthopedic force, the greater maximum von Mises stress in the bone and maximum displacement of the miniscrew. It was observed that in C plate, the von Mises stress in the bone and displacement of the miniscrew were distributed around the distalmost screw-fixed area. Conclusions: The results suggest that Y plate should have the advantage over C plate and in the placement of the miniplate, its imaginary axis should be placed as parallel as possible to the direction of orthopedic force to obtain its primary stability.

• The Journal of Advanced Prosthodontics
• /
• 제5권3호
• /
• pp.333-340
• /
• 2013

PURPOSE. This study was accomplished to assess the biomechanical state of different retaining methods of bar implant-overdenture. MATERIALS AND METHODS. Two 3D finite element models were designed. The first model included implant overdenture retained by Hader-clip attachment, while the second model included two extracoronal resilient attachment (ERA) studs added distally to Hader splint bar. A non-linear frictional contact type was assumed between overdentures and mucosa to represent sliding and rotational movements among different attachment components. A 200 N was applied at the molar region unilaterally and perpendicular to the occlusal plane. Additionally, the mandible was restrained at their ramus ends. The maximum equivalent stress and strain (von Mises) were recorded and analyzed at the bone-implant interface level. RESULTS. The values of von Mises stress and strain of the first model at bone-implant interface were higher than their counterparts of the second model. Stress concentration and high value of strain were recognized surrounding implant of the unloaded side in both models. CONCLUSION. There were different patterns of stress-strain distribution at bone-implant interface between the studied attachment designs. Hader bar-clip attachment showed better biomechanical behavior than adding ERA studs distal to hader bar.

• The Journal of Advanced Prosthodontics
• /
• 제5권3호
• /
• pp.326-332
• /
• 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.

• 한국임상수의학회지
• /
• 제35권3호
• /
• pp.83-87
• /
• 2018

The aim of this study was to evaluate the biomechanical behavior of xenogenic bone plate system (equine bone) using a three-dimensional finite element ulna fracture model. The model was used to calculate the Von Mises stress (VMS) and stress distribution in fracture healing periods with metallic bone plate and xenogenic bone plate systems, which are installed while the canine patient is standing. Bone healing rate (BHR) (0%) and maximum VMS of the xenogenic plate was similar to the yield strength of equine bone (125 MPa). VMS at the ulna and fracture zones were higher with the xenogenic bone plate than with the metallic bone plate at BHRs of 0% and 1%. Stress distributions in fracture zone were higher with the xenogenic bone plate than the metallic bone plate. This study results indicate that the xenogenic bone plate may be considered more beneficial for callus formation and bone healing than the metallic bon plate. Xeonogenic bone plate and screw applied in clinical treatment of canines may provide reduced stress shielding of fractures during healing.

• 한국생산제조학회지
• /
• 제19권4호
• /
• pp.469-475
• /
• 2010

The objective of this study is to integrate reliability analysis into shape optimization problem using the evolutionary structural optimization (ESO) in the application example. Reliability-based shape optimization is formulated as volume minimization problem with probabilistic stress constraint under minimization max. von Mises stress and allow stress. Young's modulus, external load and thickness are considered as uncertain variables. In order to compute reliability index, four methods, i.e., reliability index approach (RIA), performance measure approach (PMA), single-loop singlevector (SLSV) and adaptive-loop (ADL), are used. Reliability-based shape optimization design process is conducted to obtain optimal shape satisfying max. von Mises stress and reliability index constraints with the above four methods, and then each result is compared with respect to numerical stability and computing time.

• Structural Engineering and Mechanics
• /
• 제58권4호
• /
• pp.731-743
• /
• 2016

Plastic behaviors, based on the von Mises yield criterion, of circular discs containing a purely elastic, circular inclusion under uniform temperature loading are studied with the finite element analysis. Temperature-dependent mechanical properties are considered for the matrix material only. In addition to analyzing the plane stress and plane strain disc, a 3D thin disc and cylinder are also analyzed to compare the plane problems. We determined the elastic irreversible temperature and global plastic collapse temperature by the finite element calculations for the plane and 3D problem. In addition to the global plastic collapse, for the elastically hard case, the plane stress problem and 3D thin disc may exhibit a local plastic collapse, i.e. significant pile up along the thickness direction, near the inclusion-matrix interface. The pileup cannot be correctly modeled by the plane stress analysis. Furthermore, due to numerical difficulties originated from large deformation, only the lower bound of global plastic collapse temperature of the plane stress problem can be identified. Without considerations of temperature-dependent mechanical properties, the von Mises stress in the matrix would be largely overestimated.

• 한국기계기술학회지
• /
• 제20권6호
• /
• pp.901-905
• /
• 2018

The objective of this study is to investigate the effect of torque variation on stress distributions in A-IMS module with both side tubular shaft yoke by numerically. In order to achieve this, the torque value was increased from 10Nm to 40Nm, and the results of this work were confirmed in terms of Von-mises Stress and the displacement characteristics. As the torque in module assembly was increased, the stress in tubular shaft york and splined shaft york was increased linearly. The indentation due to the steel ball was occurred in over $40N{\cdot}m$ torque which is over the yield strength condition. The largest displacement occurred in the tubular shaft yoke 1, however, it does not exceed the yield strength and is supposed to be restored due to the elasticity. Therefore, it was concluded that there is no problem for the manufacturing of A-IMS with both side tubular shaft yoke.

• 드라이브 ㆍ 컨트롤
• /
• 제20권4호
• /
• pp.9-16
• /
• 2023

This paper analyzed a drainage tower used to drain water in flooded areas. Multi-body dynamics simulation was used to analyze the dynamic behavior of the drainage tower. Structural analysis, flexible-body dynamic analysis, and rigid body dynamic analysis were done to study the maximum Von-Mises stress of the drainage tower. The results showed that the maximum Von-Mises stress occurs at the turn table, and it decreases when the angle of the boom is increased. Also, the rate of the change of angle affects the maximum stress so that the maximum stress changes more when the angular velocity of the boom increases. Based on the rigid body dynamic analysis and the theoretical analysis results, the centrifugal force from the angular velocity makes the difference in the maximum stress at the turn table because of the difference in their direction. Consequently, it was concluded that the centrifugal force should be considered when designing construction machinerythat can rotate.