• Title/Summary/Keyword: Mode I Loading

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횡전기장이 강유전체 세라믹의 파괴거동에 미치는 영향 (Effect of Transverse Electric Fields on Fracture Behavior of Ferroelectric Ceramics)

  • 이종식;범현규;정경문
    • 한국정밀공학회지
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    • 제22권2호
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    • pp.120-125
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    • 2005
  • Effect of transverse electric fields on fracture behavior in ferroelectric ceramics under purely electrical loading is investigated. It is shown that the shape and size of the domain switching zone depend strongly on the ratio of the transverse electric field to the coercive electric field as well as the direction of the applied electric field. Under small-scale conditions, the crack-tip mode I and II stress intensity factors induced by ferroelectric domain switching are numerically obtained. The crack kinking in ferroelectric ceramics is also discussed.

필릿 용접이음부의 피로파괴 특성에 관한 연구 (A Study on the Characteristics of Fatigue Failure for Fillet Welded Joint)

  • 강성원;하우일;신종석;장태원;제정신
    • 대한조선학회논문집
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    • 제33권4호
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    • pp.133-141
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    • 1996
  • 하중 전달형 필릿 용접 이음부에서 피로파괴는 용접투우부와 용접루트부로 부터 발생된 피로균열 발생 및 전파의 특성에 지배된다. 또한 그 피로균열의 특성은 필릿의 형상과 응력범위에 따라 큰 영향을 받는다. 본 연구의 목적은 하중 전달형 십자형 필릿 용접 이음부에서 피로하중 작용시 용접토우부에서 파괴하기 이한 용접부의 임계다리길이와 응력범위등을 검토하는 것이다.

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원심모형실험에 의한 모래다짐말뚝의 지지력 산정식 연구 (A Study on Estimation of Bearing Capacity of Sand Compaction Pile by Centrifuge Model Tests)

  • 유남재;홍영길;전상현;김경수
    • 산업기술연구
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    • 제27권A호
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    • pp.121-130
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    • 2007
  • Centrifuge model tests were performed to find appropriate equations proposed previously of estimating the bearing capacity of the composite clayey soil reinforced with sand compaction pile. Model tests were carried out with changing the replacement ratio of SCP (20%, 40%, 70%), contents of fine materials (5%, 10%, 15%) and ratio of treated width to loading width (1B, 2B, 3B). Test results about bearing capacity of the composite ground were obtained by performing the surcharge load tests with measurements of applied loads and vertical displacement. Bearing capacities against bulging and shear failures were estimated by the existing equations. As results of comparing the estimated bearing capacity with experimental values the bearing capacities estimated by Greenwood's equation (1970) for bulging failure mode were similar to the test results.

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광탄성실험에 의한 함수구배 재료 균열 해석 (Analysis for Cracks of Functionally Gradient Materials by Photoelastic Experiment)

  • 이광호
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2004년도 춘계학술대회
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    • pp.48-53
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    • 2004
  • This paper suggested the method determing the stress intensity factor (SIF) for functionally gradient materials (FGMs) by photo elastic experimental method. The SIF for the center crack in a finite rectangulat plate with a linear variation of shear modulus with constant density and Poisson's ratio along the direction of the crack under mode I static loading is obtained. The exponential and linear variation of stress fields are used for obtaining the SIF. The greater crack length, the increaser the difference of the SIF between right and left side crack tip.

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Inelastic distortional buckling of cantilevers

  • Lee, Dong-Sik;Bradford, Mark Andrew
    • Steel and Composite Structures
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    • 제3권1호
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    • pp.1-12
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    • 2003
  • Cantilevers are unique statically determinate structural elements with respect to their mode of overall buckling, in that the tension flange is the critical flange under gravity loading, and is the flange that deflects greatest during overall buckling. While this phenomenon does not complicate the calculation of the lateral buckling load, either theoretically or in structural design codes, it has been shown in previous research that the influence of distortion in the elastic buckling of cantilevers is not the same as that experienced in the elastic buckling of simply supported beams. This paper extends the study of the distortional buckling of cantilevers into the hitherto unconsidered inelastic range of structural response. A finite element method for studying the inelastic bifurcative instability of members whose cross-sections may distort during buckling is described, and the efficacy of the method is demonstrated. It is then used to study the inelastic distortional buckling of hot-rolled I-section cantilevers with two common patterns of residual stresses, and which may be restrained elastically from buckling by other structural elements.

Efficient methods for integrating weight function: a comparative analysis

  • Dubey, Gaurav;Kumar, Shailendra
    • Structural Engineering and Mechanics
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    • 제55권4호
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    • pp.885-900
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    • 2015
  • This paper introduces Romberg-Richardson's method as one of the numerical integration tools for computation of stress intensity factor in a pre-cracked specimen subjected to a complex stress field across the crack faces. Also, the computation of stress intensity factor for various stress fields using existing three methods: average stress over interval method, piecewise linear stress method, piecewise quadratic method are modified by using Richardson extrapolation method. The direct integration method is used as reference for constant and linear stress distribution across the crack faces while Gauss-Chebyshev method is used as reference for nonlinear distribution of stress across the crack faces in order to obtain the stress intensity factor. It is found that modified methods (average stress over intervals-Richardson method, piecewise linear stress-Richardson method, piecewise quadratic-Richardson method) yield more accurate results after a few numbers of iterations than those obtained using these methods in their original form. Romberg-Richardson's method is proven to be more efficient and accurate than Gauss-Chebyshev method for complex stress field.

순환굵은골재 치환율에 따른 콘크리트의 압축파괴 및 음향방출특성 (The Effect of Recycled Coarse Aggregates Replacement Level on Localized Fracture and Acoustic Emission of Concrete in Compression)

  • 김윤수;윤현도;유영찬
    • 한국콘크리트학회:학술대회논문집
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    • 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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    • pp.249-252
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    • 2006
  • When concrete is subjected to uniaxial compression, the failure process is normally initialed from a localized zone. The localization of failure governs structural behaviors of concrete. In this paper, the compressive strength and failure behavior of recycled coarse aggregate concrete with different replacement level of recycled coarse aggregates are investigated using acoustic emission(AE). AE characteristics of concrete were investigated during the entire loading period. For these purpose, four recycled coarse aggregate replacement level (i.e 0%, 30%, 60% and 100%) were considered in this paper. Result from this study show AE signal, AE method can apply to investigate a compressive failure mode according to recycled coarse replacement level.

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대형 컨테이너 선박의 유탄성 실선 계측 데이터 분석 Part I - 모달 파라미터 추정 (Full Scale Measurement Data Analysis of Large Container Carrier with Hydroelastic Response, Part I - Identification of Modal Parameters)

  • 김병훈;최병기;박준석;박성건;기혁근;김유일
    • 대한조선학회논문집
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    • 제55권1호
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    • pp.37-44
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    • 2018
  • To understand the dynamic characteristics of the vessel with hydroelastic response, it is very important to estimate the dynamic modal parameters such as mode shapes, natural frequency, and damping ratio. These dynamic modal parameters of full scale ship are a priori unknowns, hence to be estimated directly based upon the full scale measurement data. In this paper, dynamic modal parameters were extracted by signal processing of acceleration and strain data measured from a large container ship whose loading capacity is 9400TEU. The mode shapes of the vibrating hull were identified using the proper orthogonal decomposition and the vibration response of hull was decomposed into its modal magnitudes. Natural frequencies of specific modes were derived via Fourier transform of these modal magnitude. Also, the free decay signal of the vibrating hull was obtained through the random decrement technique and the damping ratio was estimated with accuracy.

인공추간판의 피로하중 모드에 따른 슬라이딩 코어의 피로균열전파 거동 (Fatigue Crack Propagation of Sliding Core in Artificial Intervertebral Disc due to the Fatigue Loading Mode)

  • 김철웅;강봉수
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 2006년도 춘계학술대회 논문집
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    • pp.367-368
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    • 2006
  • Today, the Artificial Intervertebral Disc (AID) is being developed by increasing the oblique of the endplate gradually. In other words, Ultra-high Molecular Weight Polyethylene (UHMWPE) which is apply to the sliding core of the AID, does not change the shape but alters the oblique of endplate. However, the unreasonable increase of degree of freedom (DOF) can result in the aggravation of the bone fusion and the initial stability and it can also lead to the increase of the concentrated force in core. For these reasons, it is necessary to develop the advanced techniques, which choose the most adequate DOF. In this study, the new optimized modeling of the sliding core and the endplate, the fatigue characteristics, the crack propagation and the formation mechanism of wearing debris was studied and the minimizing technique will be derived from this research.

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Multiple unequal cracks between an FGM orthotropic layer and an orthotropic substrate under mixed mode concentrated loads

  • M. Hassani;M.M. Monfared;A. Salarvand
    • Structural Engineering and Mechanics
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    • 제86권4호
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    • pp.535-546
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    • 2023
  • In the present paper, multiple interface cracks between a functionally graded orthotropic coating and an orthotropic half-plane substrate under concentrated loading are considered by means of the distribution dislocation technique (DDT). With the use of integration of Fourier transform the problem is reduced to a system of Cauchy-type singular integral equations which are solved numerically to compute the dislocation density on the surfaces of the cracks. The distribution dislocation is a powerful method to calculate accurate solutions to plane crack problems, especially this method is very good to find SIFs for multiple unequal cracks located at the interface. Hence this technique allows considering any number of interface cracks. The primary objective of this paper is to investigate the effects of the interaction of multiple interface cracks, load location, material orthotropy, nonhomogeneity parameters and geometry parameters on the modes I and II SIFs. Numerical results show that modes I/II SIFs decrease with increasing the nonhomogeneity parameter and the highest magnitude of SIF occurs where distances between the load location and crack tips are minimal.