• 제목/요약/키워드: edge loading

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FATIGUE DAMAGE PARAMETER OF SPOT WELDED JOINTS UNDER PROPORTIONAL LOADING

  • KANG H. T.
    • International Journal of Automotive Technology
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    • 제6권3호
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    • pp.285-291
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    • 2005
  • In this paper, the author proposes a fatigue damage parameter of spot welded joints under proportional loading. The proposed fatigue damage parameter is developed based on von Mises' equivalent stress and local structural stress at the edge of spot weld nugget. The structural stress at the edges of the weld nugget in each sheet is calculated using the forces and moments that are determined by finite element analysis. A structural equivalent stress is then calculated by von Mises' equivalent stress equation. The structural equivalent stresses are correlated to experimental fatigue life of the spot welded joints. The proposed parameter is evaluated with fatigue test data of spot welds subjected to multi axial and tensile-shear loads. Sheppard's parameter and Rupp and co-workers' parameter are also evaluated with the same test data to compare with the author's parameter. This proposed parameter presents a better correlation with experimental fatigue data than those of Sheppard's and Rupp and co-workers' parameter. The proposed parameter should be very effective for durability calculations during the early design phase since coarsely meshed finite element models can be employed.

두께가 변화하는 부재 내의 혼합모드(모드 I/II) 균열의 응력확대계수 (Stress Intensity Factors of Combined Mode(Mode I/II) Crack in a Variable Thickness Plate)

  • 조명래;양원호;최용식
    • 대한기계학회논문집
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    • 제17권8호
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    • pp.1875-1882
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    • 1993
  • Variable thickness plates are commonly used as structural members in the majority of industrial sectors. Previous fracture mechanics researches on variable thickness plates were limited to mode I loading cases. In practice, however, cracks are usually located inclined to the loading direction. In this respect, combined mode(mode I/II) stress intensity factors $K_{I}$ and $K_{II}$ at the crack tip for a variable thickness plate were obtained by 3-dimensional finite element analysis. Variable thickness plates containing a slant edge crack were chosen. The parameters used in this study were dimensionless crack $length{\lambda}$, slant $angle{\alpha}$, thickness $ratio{\beta}$ and width ratio{\omega}$. Stress intensity factors were calculated by crack opening displacement(COD) and crack sliding displacement(CSD)method proposed by Ingraffea and Manu.

A treatise on irregular shaped concrete test specimens

  • Gorkem, Selcuk Emre
    • Computers and Concrete
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    • 제16권1호
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    • pp.179-190
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    • 2015
  • An experimental program has been carried out to investigate the effect of edge-slope on compressive strength of concrete specimens. In this study, effect of such slope was investigated by testing 100 standard cylinder specimens and 40 standard cubes. When molds are put on a slanted place, wet concrete starts to flow through the open end of mold. It keeps flowing until it reaches to a parallel surface with the place over which it was placed. That creates a sloped surface over the loading area. Experimental results revealed significant relationships between failure loads and slope of loading surface for cylinders. Angled cracks occurred in sloped cylinder specimens. Tension cracks occurred in cube specimens. Fracture mechanisms were also evaluated by using finite element analyses approach. Experiments yielded an exponential curve with bandwidth for cylinders. Average value of curve is $y={\frac{\pi}{2}}e^{-cf}$ between slope and compressive strength. Inclination is much effective parameter for cylinders than cubes.

A study on the measurement of plastic zone and crack growth length at the crack tip under cyclic loading using ESPI system

  • Kim, Kyung-Su;Kim, Ki-Sung;Shim, Chun-Sik
    • Structural Engineering and Mechanics
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    • 제15권3호
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    • pp.367-378
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    • 2003
  • The magnitude of the plastic zone around the crack tip of DENT (Double Edge Notched Tension) specimen and the crack growth length under cyclic loading were measured by ESPI (Electronic Speckle Pattern Interferometry) system. The measured magnitude of plastic zone was compared with the proposed by Irwin and calculated by a nonlinear static method of MSC/NASTRAN. The measured crack growth length by ESPI system was also compared with the obtained data by the image analysis system. From the study, it is confirmed that the plastic zone and crack growth length can be measured accurately with the high-tech equipment (ESPI System).

용접구조물 피로해석 적용을 위한 기준응력 비교 연구 (A Benchmark study on the reference stress to supply fatigue analysis of welded structure)

  • 서정관;최홍민;이제명;백점기;김명현;김현수
    • 한국전산구조공학회:학술대회논문집
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    • 한국전산구조공학회 2004년도 가을 학술발표회 논문집
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    • pp.421-428
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    • 2004
  • Various type of welded joints of the ship structure have been examined numerically and experimentally under bending and tensional cyclic constant-amplitude loading. Cyclic loading on structures can produce failures not readily predicted by conventional static analysis. The aim of a benchmark study is achieved with a generalization of the reference stress concept. Also different methods and procedures exist for the computation of the welded structure hot-spot stress a welded joints. These are either based on the extrapolation of stresses at certain reference points on the plate surface (or edge) close to the weld toe-as known from experimental investigations- or on the linearization of stresses in the through-thickness direction. In the present paper, the different methods are reviewed and applied to four different details in order to compare the methods with each other and to illustrate the differences.

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Static and dynamic behaviour of square plates with inhomogeneity subjected to non-uniform edge loading (compression and tension)

  • Prabhakara, D.L.;Datta, P.K.
    • Structural Engineering and Mechanics
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    • 제4권2호
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    • pp.163-176
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    • 1996
  • The tension and compression buckling behaviour of a square plate with localized zones of damage and subjected to non-uniform loading is studied using a finite element analysis. The influence of parameters such as position of damage, extent of damage, size of damage and position of load on instability behaviour are discussed. The dynamic behaviour for certain load and damage parameters are also presented. It is observed that the presence of damage has a marked effect on the static buckling load and natural frequency of the plate.

전자스패클패턴 간섭시스템을 이용한 피로하중을 받는 균열선단에서 탄소성 영역 측정에 관한 연구 (A Study on the Measurement of Elastic-Plastic Zone at the Crack Tip under Cyclic Loading using ESPI System)

  • 김경수;심천식
    • 한국해양공학회지
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    • 제16권4호
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    • pp.13-18
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    • 2002
  • The magnitude of the plastic zone around the crack tip of DENT(Double Edge Notched Tension) specimen and the crack growth length under cyclic loading were measured by ESPI(Electronic Speckle Pattern Interferometry) system. The measured magnitude of plastic zone was compared with the equations proposed by Irwin and calculated by a nonlinear static method of MSC/NASTRAN. The measured crack growth length by ESPI system was also compared with the obtained data by the image analysis system. From the study, it is confirmed that the plastic zone and crack growth length can be measured accurately with the high-tech equipment.

Mixed mode fracture assessment of U-notched graphite Brazilian disk specimens by means of the local energy

  • Torabi, A.R.;Berto, F.
    • Structural Engineering and Mechanics
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    • 제50권6호
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    • pp.723-740
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    • 2014
  • A fracture criterion based on the strain energy density (SED) over a control volume, which embraces the notch edge, is employed in the present paper to assess the fracture loads of some U-notched Brazilian disk (UNBD) specimens. The specimens are made of commercial graphite and have been tested under pure mode I, pure mode II and mixed mode I/II loading. The results show that the SED criterion allows to successfully assess the fracture loads of graphite specimens for different notch tip radii and various mode mixity conditions with discrepancies that fall inside the scatter band of ${\pm}20%$.

응력함수에 기초한 복합 하중하의 복합재 적층판의 층간응력 해석 (Stress Function-Based Interlaminar Stress Analysis of Composite Laminates under Complex Loading Conditions)

  • 김흥수;김정윤;김진곤
    • 동력기계공학회지
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    • 제14권3호
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    • pp.52-57
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    • 2010
  • Interlaminar stresses near the free edges of composite laminates have been analyzed considering wall effects. Interface modeling of bonding layer was introduced to explain the wall effect. Using Lekhnitskii stress functions and the principle of complementary virtual work, the interlaminar stresses were obtained, which satisfied the traction free boundary conditions not only at the free edges, but also at the top and bottom surfaces of laminates. The interface modeling provides not singular stresses but concentrated finite interlaminar stresses. The significant amount of reductions of stresses at the free edge are observed compared to the results without interface modeling. The real stress state can be predicted accurately and the results demonstrate the usefulness of the proposed interface modeling for the strength design of composite laminates.

Some Studies on Stress field in Dissimilar Materials

  • Katsuhiko Watanabe
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 1996년도 추계학술대회 논문집
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    • pp.631-635
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    • 1996
  • Stress singularities appear at the interface edge in dissimilar materials also under thermal loading. First, these singularities then an interface meets a free side surface with an arbitrary angle are studied for a two-dimensional problem. The singular properties under thermal loading are made clear and the concrete singular field are obtained. Secondly, the dependence of stress field on elastic constants in axisymmetric dissimilar materials are. discussed. That is, it is shown that three elastic constants mutually independent are necessary, in general, to characterize the stress field of axisymmetric dissimilar materials, although Dunders' parameters defined for two-dimensional dissimilar materials have been often applied correspondingly also to axisymmetric problems.

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