• 제목/요약/키워드: new strain

검색결과 2,120건 처리시간 0.031초

A new strain-based criterion for evaluating tunnel stability

  • Daraei, Ako;Zare, Shokrollah
    • Geomechanics and Engineering
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    • 제16권2호
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    • pp.205-215
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    • 2018
  • Strain-based criteria are known as a direct method in determining the stability of the geomechanical structures. In spite of the widely use of Sakurai critical strain criterion, it is so conservative to make use of them in rocks with initial plastic deformation on account of the considerable difference between the failure and critical strains. In this study, a new criterion has been developed on the basis of the failure strain to attain more reasonable results in determining the stability status of the tunnels excavated in the rocks mostly characterized by plastic-elastic/plastic behavior. Firstly, the stress-strain curve was obtained having conducted uniaxial compression strength tests on 91 samples of eight rock types. Then, the initial plastic deformation was omitted making use of axis translation technique and the criterion was presented allowing for the modified secant modulus and by use of the failure strain. The results depicted that the use of failure strain criterion in such rocks not only decreases the conservativeness of the critical strain criterion up to 42%, but also it determines the stability status of the tunnel more accurately.

새로운 Tension Split Hopkinson Bar를 이용한 박판의 고속 인장시험 (High strain rate tensile test of sheet metals with a new tension split hopkinson bar)

  • 강우종;조상순;허훈;정동택
    • 대한기계학회논문집A
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    • 제21권12호
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    • pp.2209-2219
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    • 1997
  • A split hopkinson bar could be used for obtaining the high strain rate material properties of sheet metals for an autobody. In high speed tensile tests of sheet matals, a new design of a tension split Hopkinson bar apparatus is needed. The design of grips and an anvil length are numerically analyzed with ABAQUS/Explicit for the new apparatus of split Hopkinson bars. From the experiments with the new apparatus, the material properties of SPCEN in the high strain rate state have been acquired and compared with quasi-static experimental results. The material properties of SPCEN as well as other sheet metals in an autobody are indispensible for the analysis of crashworthness. Nevertheless the experiment of sheet metal in the high strain rate state has not been done or reported.

승용차용 SPC 3 EN 킬드 강판의 등 2축 인장 가공성에 관한 연구 (A Study on the Equi-Biaxial Tensile Workability for the SPC 3 EN Automobile Killed Steel Sheets)

  • 김동원;서대교;김형종
    • 대한기계학회논문집
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    • 제10권5호
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    • pp.645-652
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    • 1986
  • 본 연구는 이상의 연구결과들을 비교한 결과, Hill에 의하여 최근에 제안된 새 항복조건식에 의한 해석방법을 종합 검토함으로써, 실험결과와 이론적 해석결과 와의 합리적인 접근을 얻을 수 있다고 예상하여 수행되었다. 더 나아가 Pearce가 그의 연구 결과에 대한 고찰에서, 아마도 R 값(Lankford값)이 변형도중에 계속 일정 하게 유지되지 않을 것이며, 그것이 실험결과가 이론적 해석결과와 일치하지 않는 한 가지 원인이 될 수 있다고 언급한 사실을 고려하고, 최근 R 값에 대한 연구에서 R 값 이 변형률의 크기에 의존된다는 사실을 감안하여 R 값을 실제로 측정하였으며, 그 결 과를 등 2축인장에서의 응력-변형률선도를 해석하는데 적용하였다.

초고층 건축물의 부등축소량 예측을 위한 뉴랄-네트워크의 적용 (Application of Neural Network to Prediction of Column Shortening of High-rise Buildings)

  • 양원직;이정한;김욱종;이도범;이원호
    • 한국콘크리트학회:학술대회논문집
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    • 한국콘크리트학회 2006년도 춘계학술발표회 논문집(I)
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    • pp.494-497
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    • 2006
  • The objectives of this study are to develop and evaluate the Neural Network algorithm which can predict the inelastic shortening such as the creep strain and the drying shrinkage strain of reinforced concrete members using the previous test data. New learning algorithms for the prediction of creep strain and the drying shrinkage strain are proposed focusing on input layer components and a normalization method for input data and their validity is examined through several test data. In Neural Network algorithm, the main input data to be trained are the compressive strength of the concrete, volume to surface ratio, curing condition, relative humidity, and the applied load. The results show that the new algorithms proposed herein successfully predict creep strain and the drying shrinkage strain.

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다층 구조에 대한 새로운 strain 해석 모델 (A new strain analysis model in epitaxial multilayer system)

  • 장동현;심종인
    • 한국광학회:학술대회논문집
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    • 한국광학회 2007년도 하계학술발표회 논문집
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    • pp.237-238
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    • 2007
  • A new strain analysis model, so called the stress matched model, in an epitaxial multilayer system is proposed. The model makes it possible to know the strain, the stress, the elastic strain energy in each epitaxial layer. Analytical formulas of strain parameters in each epitaxial layer are derived under assumptions that the substrate thickness is finite and the in-plane lattice constant is the same for all epitaxial layers for dislocation free growth. As an example, the model is applied to a 405nm InGaN/InGaN multiple quantum well laser diode. Analysis result shows that AlxGa1-xN layer with Al mole fraction of 0.06 and the thickness of 6${\mu}m$ is one of good templates for a laser. In fact, this layer structure coincides with experimentally optimized one.

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Isolation and Characterization of a New Fluorescent Pseudomonas Strain that Produces Both Phenazine 1-Carboxylic Acid and Pyoluteorin

  • HU, HONG-BO;XU, YU-QUAN;FENG CHEN;XUE HONG ZHANG;HUR, BYUNG-KI
    • Journal of Microbiology and Biotechnology
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    • 제15권1호
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    • pp.86-90
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    • 2005
  • Strain M-18 was isolated from the rhizosphere soil of sweet melon, using 1-aminocyclopropane-1-carboxylate (ACC) as a sole nitrogen source. Its phenotypic characteristics, metabolic tests, and 16S rDNA sequence were analyzed. The antibiotics secreted by strain M-18 were determined to be phenazine 1-carboxylic acid and pyoluteorin. These data showed that strain M-18 was a new fluorescent Pseudomonas strain that produced both phenazine 1-carboxylic acid and pyoluteorin, some features being similar to Pseudomonas aeruginosa and Pseudomonas fluorescens. Therefore, the strain M-18 appears to be the first pseudomonad described to date that is capable of producing both phenazine 1-carboxylic acid and pyoluteorin.

Evolution of post-peak localized strain field of steel under quasi-static uniaxial tension: Analytical study

  • Altai, Saif L.;Orton, Sarah L.;Chen, Zhen
    • Structural Engineering and Mechanics
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    • 제83권4호
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    • pp.435-449
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    • 2022
  • Constitutive modeling that could reasonably predict and effectively evaluate the post-peak structural behavior while eliminating the mesh-dependency in numerical simulation remains to be developed for general engineering applications. Based on the previous work, a simple one-dimensional modeling procedure is proposed to predict and evaluate the post-peak response, as characterized by the evolution of localized strain field, of a steel member to monotonically uniaxial tension. The proposed model extends the classic one-dimensional softening with localization model as introduced by (Schreyer and Chen 1986) to account for the localization length, and bifurcation and rupture points. The new findings of this research are as follows. Two types of strain-softening functions (bilinear and nonlinear) are proposed for comparison. The new failure criterion corresponding to the constitutive modeling is formulated based on the engineering strain inside the localization zone at rupture. Furthermore, a new mathematical expression is developed, based on the strain rate inside and outside the localization zone, to describe the displacement field at which bifurcation occurs. The model solutions are compared with the experimental data on four low-carbon cylindrical steel bars of different lengths. For engineering applications, the model solutions are also compared to the experimental data of a cylindrical steel bar system (three steel bars arranged in series). It is shown that the bilinear and nonlinear softening models can predict the energy dissipation in the post-peak regime with an average difference of only 4%.

새로운 평면변형률 시험장비의 개발과 적용성 검증 (A Newly-developed Plane Strain Testing Device and Its Applicability)

  • 김창엽;이용선;정충기
    • 한국지반공학회논문집
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    • 제22권1호
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    • pp.5-14
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    • 2006
  • 본 연구에서는 평면변형률조건하에서 발생 가능한 다양한 응력조건을 보다 자유롭게 구현할 수 있는 간편한 형태의 평면변형률 시험장비를 새롭게 개발하였다. 개발된 시험장비의 적용성은 먼저 이상화된 가정조건하에서 이론적으로 검토되었으며, 실제 점성토시료에 대한. 일련의 평면변형률시험을 통해 실험적으로 확인 검증되었다. 그 결과 개발된 시험장비는 기존의 평면변형률 시험장비들에 비해 광범위한 적용성을 가지고 있음을 확인할 수 있었다. 또한 개발된 시험장비는 일반적인 삼축시험용 재하장치만으로도 다양한 응력조건에 대한 평면변형률시험이 가능하므로, 향후 관련분야에서 그 활용도가 매우 높을 것으로 기대된다.

정밀가공면의 소성스트레인 측정을 위한 새로운 기법의 개발 (A New Technique Development for Measuring Plastic Strain of Precision Machined Surface)

  • 김태영;반야풍;문상돈
    • 한국정밀공학회지
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    • 제15권4호
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    • pp.141-147
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    • 1998
  • A plastically deformed layer in the precision machined surface affects in various forms the physical properties of machined components such as the fatigue strength, the dimensional instability, microcracks and the stress corrosion cracking. These physical properties, so called surface integrity, are very important for designing highly stressed and critically loaded components. Typical plastic strains in the precision machined surface are very difficult to measure, since they are located within a very short distance from the surface and they change very rapidly. A new way is suggested to determine the residual strain in plastically deformed materials by analyzing the plastically deformed layer after a subsequent recrystallization process. This investigation is to explore a new technique for measuring plastic strain in machining applications, and in particular, to and the effect of cutting parameters(rake angle, depth of cut, specific cutting energy), on the plastic strains and strain energy.

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스트레인 게이지형 센서 신호조정기 자동교정 및 시뮬레이션 기법 (Auto Calibration and Simulation Method for a Strain Gage Type Transducer/Signal Conditioner)

  • 유제택
    • 제어로봇시스템학회논문지
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    • 제9권12호
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    • pp.1019-1025
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    • 2003
  • We introduce a new auto-calibration/simulation method for a strain gage type transducer/signal-conditioner which guarantees the output linearity and compensates the error automatically. We design a micro voltage supply which is able to interface either AC or DC type excitation voltage. A new strain gage simulator is also designed. We make linearity output of the signal conditioner and can compensate error automatically with this new auto calibration/simulation method. The experimental results show that the error between the real value and the expected one is less than 1%.