• Title/Summary/Keyword: Yon mises stress

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Optimal Design of a Nuclear Fuel Rod Support Structure Based on Contact Stress Analysis (접촉응력해석을 통한 핵연료 지지격자 구조물의 최적설계)

  • Jang, In-Gwun;Kwak, Byung-Man;Song, Kee-Nam
    • Proceedings of the KSME Conference
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    • 2000.04a
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    • pp.731-736
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    • 2000
  • An optimal design method is adopted for a spacer grid in nuclear power plant. It is made of punched sheet metal process, functioning as springs and dimples supporting fuel rods. For stress analysis of the assembled fuel rod support, a typical cell out of the repeated pattern in the assembly is modeled using 4-node shell elements. A commercial code, ABAQUS, is used for detailed analysis of contacting phenomena with friction. For the optimization, design varibles are taken from geometric parameters representing the shape of the bent leaf spring part and mating contact region with fuel rod. Objective function is considered in relation to mechanical functions and durability. Maximum yon Mises stress is considered in relation to constrained contact stress.

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A Study on Small Punch-Creep Test Using Finite Element Analysis II (유한요소해석을 이용한 소형펀치-크리프 시험에 관한 연구 (II) - SP-Creep 시험과 일축 크리프 시험의 상관성을 중심으로 -)

  • Lee, Song-In;Kwon, Il-Hyun;Kim, Yon-Jig;Ahn, Byung-Guk;Ahn, Haeng-Keun;Baek, Seung-Se;Yu, Hyo-Sun
    • Proceedings of the KSME Conference
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    • 2001.11a
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    • pp.111-116
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    • 2001
  • Small punch-creep(SP-Creep) test technique has been applied for evaluating the creep characteristics for high temperature materials. However, in order to evaluate the damage and predict the remaining life, it is necessary to establish a quantitative correlation between SP-Creep and uniaxial-creep test results. This paper presents analytical and experimental results of useful correlation between SP-Creep and uniaxial-creep properties for 9Cr1MoVNb steel at $600{\sim}650^{\circ}C$ in terms of stress(load) and activation energy during creep deformation. Especially, the activation energy obtained from SP-Creep test is linearly related to that from uniaxial-creep test at $650^{\circ}C$ as follows: $Q_{sp-p}{\fallingdotseq}1.37\;Q_{TEN},\;Q_{sp-{\sigma}}{\fallingdotseq}1.53\;Q_{TEN}$.

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THREE DIMENSIONAL FINITE ELEMENT STRESS ANALYSIS OF IMPLANT PROSTHESIS ACCORDING TO THE DIFFERENT FIXTURE LOCATIONS AND ANGULATIONS (임플랜트 지지 보철물에서 고정체의 식립위치와 각도에 따른 삼차원 유한요소법적 응력분석에 관한 연구)

  • Park Won-Hee;Lee Young-Soo
    • The Journal of Korean Academy of Prosthodontics
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    • v.43 no.1
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    • pp.61-77
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    • 2005
  • Statement of problem. The implant prosthesis has been utilized in various clinical cases thanks to its increase in scientific effective application. The relevant implant therapy should have the high success rate in osseointegration, and the implant prosthesis should last for a long period of time without failure. Resorption of the peri-implant alveolar bone is the most frequent and serious problem in implant prosthesis. Excessive concentration of stress from the occlusal force and biopressure around the implant has been known to be the main cause of the bone destruction. Therefore, to decide the location and angulation of the implant is one of the major considering factors for the stress around the implant fixture to be dispersed in the limit of bio-capacity of load support for the successful and long-lasting clinical result. Yet, the detailed mechanism of this phenomenon is not well understood. To some extent, this is related to the paucity of basic science research. Purpose. The purpose of this study is to perform the stress analysis of the implant prosthesis in the partially edentulous mandible according to the different nature locations and angulations using three dimensional finite element method. Material and methods, Three 3.75mm standard implants were placed in the area of first and second bicuspids, and first molar in the mandible Thereafter, implant prostheses were fabricated using UCLA abutments. Five experimental groups were designed as follows : 1) straight placement of three implants, 2) 5$^{\circ}$ buccal and lingual angulation of straightly aligned three implants, 3) 10$^{\circ}$ buccal and lingual angulation of straightly aligned three implants. 4) lingual offset placement of three implants, and 5) buccal offset placement of three implants. Average occlusal force with a variation of perpendicular and 30$^{\circ}$ angulation was applied on the buccal cusp of each implant prosthesis, followed by the measurement of alteration and amount of stress on each configurational implant part and peri-implant bio-structures. The results of this study are extracted from the comparison between the distribution of Von mises stress and the maximum Von mises stress using three dimensional finite element stress analysis for each experimental group. Conclusion. The conclusions were as follows : 1. Providing angulations of the fixture did not help in stress dispersion in the restoration of partially edentulous mandible. 2. It is beneficial to place the fixture in a straight vertical direction, since bio-pressure in the peri-implant bone increases when the fixture is implanted in an angle. 3. It is important to select an appropriate prosthodontic material that prevents fractures, since the bio-pressure is concentrated on the prosthodontic structures when the fixture is implanted in an angle. 4. Offset placement of the fixtures is effective in stress dispersion in the restoration of partially edentulous mandible.

A study on the finite element modeling of femur based marching cube algorithm (Marching cube 알고리즘을 이용한 대퇴골의 유한요소 모델링에 관한 연구)

  • 곽명근;오택열;변창환;이은택;유용석
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2002.10a
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    • pp.1074-1077
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    • 2002
  • Biomechanical behavior of the human femur is very important in various clinical situations. In this study, the data of FE models based on DICOM file exported from Computed tomography(CT). We generated FE models(voxel model, tetra model) of human femur using CT slide image. We compared them with Yon Mises stress results derived from finite element analysis(FEA). Comparing the two models, we found a correlation of them. As a result, the tetra model based proposed marching cube algorithm is a valid and accurate method to predict parameters of the complex biomechanical behavior of human femur.

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