• 제목/요약/키워드: Strain energy density

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304 스테인레스 박강판 IB형 용접이음재의 피로강도 평가 Part 2 : 변형에너지 밀도에 의한 평가 (Fatigue Strength Evaluation on the IB-Type Spot Welded Lap Joint of 304 Stainless Steel Part 2 : Strain energy Density)

  • 손일선;오세빈;배동호
    • Journal of Welding and Joining
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    • 제17권6호
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    • pp.32-37
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    • 1999
  • Since stainless steel plates have good mechanical properties, weldability, appearance and resistance of corrosion, these are traditionally used for vehicles such as the bus and the train. And they are mainly fabricated by spot welding. But fatigue strength of their spot welded joint is considerably influenced by welding conditions as well as geometrical factors. Thus a reasonable and systematic criterion for long life design of spot welded body structure must be established. In this report, strain energy density was analyzed by using 3-dimensional finite element model about the IB-type spot welded lap joint under tension-shear load. Fatigue tests were conducted on them having various thickness, joint angle, lapped length and width. From their results, it was found that fatigue strength of the IB-type spot welded lap joints could be effectively and systematically rearranged by strain energy density at the edge of nugget.

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전변형률 에너지밀도를 이용한 고강도 저 합금강의 저주기 피로수명 예측 (Low Cycle Fatigue Life Prediction of HSLA Steel Using Total Strain Energy Density)

  • 김재훈;김덕희
    • 한국정밀공학회지
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    • 제19권6호
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    • pp.166-175
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    • 2002
  • Low cycle fatigue tests are performed on the HSLA steel that be developed for a submarine material. The relation between strain energy density and numbers of cycles to failure is examined in order to predict the low cycle fatigue life of HSLA steel. The cyclic properties are determined by a least square fit techniques. The life predicted by the strain energy method is found to coincide with experimental data and results obtained from the Coffin-Manson method. Also the cyclic behavior of HSLA steel is characterized by cyclic softening with increasing number of cycle at room temperature. Especially, low cycle fatigue characteristics and microstructural changes of HSLA steel are investigated according to changing tempering temperatures. In the case of HSLA steel, the $\varepsilon$-Cu is farmed in $550^{\circ}C$ of tempering temperature and enhances the low cycle fatigue properties.

가스산업용 안전모의 내충격 안전성에 관한 연구 (A Study on the Anti-impulsive Strength of the Helmets for a Gas Industry)

  • 김청균;김태환
    • 한국가스학회지
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    • 제17권6호
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    • pp.52-57
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    • 2013
  • 본 연구에서는 안전모 쉘 구조물의 정상부에 돌출부를 설치한 경우와 설치하지 않은 경우에 대해, 안전모의 두께와 하중면적을 변수로 변형률 에너지 밀도, 응력, 변위거동을 유한요소법으로 해석하였다. 변형률 에너지 밀도는 안전모로 전달되는 충격에너지 전달을 흡수하는 성능을 나타내는 변수로 안전모의 안전성을 고찰하는 중요한 요소 중의 하나이다. 유한요소 해석 결과에 의하면, 4,540N의 충격력이 안전모의 정상부 표면에 가해질 때 충격하중을 받는 하중면적이 증가할수록 최대응력은 선형적으로 줄어든다. 그러나, 최대 변형률 에너지 밀도는 하중면적이 증가할수록 커지는 것으로 나타났다. 변형률 에너지 밀도가 줄어들면, 안전모 착용자의 머리와 목 부분으로 전달되는 충격력은 줄어드는 것으로 나타났으며, 이것은 안전모의 충격에너지 흡수 안전성을 약화시키는 요인이 될 수 있다. 따라서, 안전모의 안전한 설계를 위해서는 정상부에 돌출 구조물을 설치하는 것이 좋지만, 이러한 수정 안전모는 충격에너지 흡수성능 측면에서는 불리함을 알 수 있다.

Inconel 617의 저주기피로 수명 예측 (Prediction of low cycle fatigue life for Inconel 617)

  • 김기광;김덕회;김재훈;이영신;박원식
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 2005년도 추계학술대회 논문집
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    • pp.612-615
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    • 2005
  • Low cycle fatigue tests are performed on the Incollel 617 that be used fur a hot gas casing. The relation between strain energy density and numbers of cycles to failure is examined in order to predict the low cycle fatigue life of Inconel 617. The life predicted by the strain energy method is found to coincide with experimental data and results obtained from the Coffin-Mansun method. Also the cyclic behavior of Inconel 617 is characterized by cyclic hardening with increasing number of cycle at room temperature.

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향상된 구형압입 고무 물성평가법 (Enhanced Spherical Indentation Techniques for Rubber Property Evaluation)

  • 황규민;오중수;이형일
    • 대한기계학회논문집A
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    • 제33권12호
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    • pp.1357-1365
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    • 2009
  • In this study, we enhance the numerical approach of Lee et al.$^{(1)}$ to spherical indentation technique for property evaluation of hyper-elastic rubber. We first determine the friction coefficient between rubber and indenter in a practical viewpoint. We perform finite element numerical simulations for deeper indentation depth. An optimal data acquisition spot is selected, which features sufficiently large strain energy density and negligible frictional effect. We then improve two normalized functions mapping an indentation load vs. deflection curve into a strain energy density vs. first invariant curve, the latter of which in turn gives the Yeoh-model constants. The enhanced spherical indentation approach produces the rubber material properties with an average error of less than 3%.

초탄성고무 물성평가용 미소압입시험기의 소프트웨어 및 하드웨어 개발 (Software and Hardware Development of Micro-indenter for Material Property Evaluation of Hyper-Elastic Rubber)

  • 이형일;김동욱;이진행;남승훈
    • 대한기계학회논문집A
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    • 제28권6호
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    • pp.816-825
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    • 2004
  • In this work, effects of hyper-elastic rubber material properties on the indentation load-deflection curve and subindenter deformation are examined via finite element (FE) analyses. An optimal location for data analysis is selected, which features maximum strain energy density and negligible frictional effect. We then contrive two normalized functions, which map an indentation load vs. deflection curve into a strain energy density vs. first invariant curve. From the strain energy density vs. first invariant curve, we can extract the rubber material properties. This new spherical indentation approach produces the rubber material properties in a manner more effective than the common uniaxial tensile/com-pression tests. The indentation approach successfully measures the rubber material properties and the corresponding nominal stress-strain curve with an average error less than 3%.

초탄성 고무 물성평가를 위한 구형 압입시험의 수치접근법 (Numerical Approach Technique of Spherical Indentation for Material Property Evaluation of Hyper-elastic Rubber)

  • 이형일;이진행;김동욱
    • Elastomers and Composites
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    • 제39권1호
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    • pp.23-35
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    • 2004
  • 본 연구에서는 먼저 유한요소해석을 통해 주요 물성계수들이 압입시 하중-변위 곡선형상에 미치는 영향을 분석하였다. 또한 유한요소 압입해석을 통해 마찰계수의 영향으로 하중-변위 곡선, 시편하부의 단위부피당 변형에너지 및 변형률 주불변량이 바뀌지 않는 최적 압입깊이와 시편하부지점을 선정하였다. 이러한 관찰을 통해 하나의 요소에서 얻어지는 단위부피당 변형 에너지와 변형률 주불변량을 하중-변위 데이터와 모사 시킬 수 있는 무차원 함수를 얻을 수 있었으며, 이 과정에서 예측된 물성계수를 바탕으로 공칭응력-공칭변형률 곡선을 얻을 수 있었다.

최소 변형 에너지 밀도 기준에 의한 콘크리트 보의 균열전파에 관한 연구 (Study on Crack Propagation of Concrete beam under Mixed-Mode Loading by Minimum Strain Energy Density Failure Criterion)

  • 진치섭;이영호;신동익;오정민
    • 한국콘크리트학회:학술대회논문집
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    • 한국콘크리트학회 1998년도 가을 학술발표논문집(II)
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    • pp.529-534
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    • 1998
  • To find out an adequate failure criterion in two-dimensional linear elastic crack problems, finite element programs, SED, which determine stress intensity factors $K_I, K_{II}$, crack angle and peak load by the minimum strain energy density failure criterion were developed. In this program, the conventional quadratic isoparametric elements were used in all regions except the crack tip zone where triangular singular elements with 6 nodes were used. The results of SED were compared with the results of those which followed by the maximum circumferential tensile stress criteria and those by the maximum energy release rate criteria and those by Jenq and Shah`s experiments of the same geometry and material properties. The maximum energy release rate criteria were better close to those of the Jenq and Shah`s experiments than the maximum circumferential tensile stress criteria and the minimum strain energy density criteria.

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Prediction of Mechanical Behavior for Carbon Black Added Natural Rubber Using Hyperelastic Constitutive Model

  • Kim, Beomkeun
    • Elastomers and Composites
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    • 제51권4호
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    • pp.308-316
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    • 2016
  • The rubber materials are widely used in automobile industry due to their capability of a large amount of elastic deformation under a force. Current trend of design process requires prediction of functional properties of parts at early stage. The behavior of rubber material can be modeled using strain energy density function. In this study, five different strain energy density functions - Neo-Hookean model, Reduced Polynomial $2^{nd}$ model, Ogden $3^{rd}$ model, Arruda Boyce model and Van der Waals model - were used to estimate the behavior of carbon black added natural rubber under uniaxial load. Two kinds of tests - uniaxial tension test and biaxial tension test - were performed and used to correlate the coefficients of the strain energy density function. Numerical simulations were carried out using finite element analysis and compared with experimental results. Simulation revealed that Ogden $3^{rd}$ model predicted the behavior of carbon added natural rubber under uniaxial load regardless of experimental data selection for coefficient correlation. However, Reduced Polynomial $2^{nd}$, Ogden $3^{rd}$, and Van der Waals with uniaxial tension test and biaxial tension test data selected for coefficient correlation showed close estimation of behavior of biaxial tension test. Reduced Polynomial $2^{nd}$ model predicted the behavior of biaxial tension test most closely.