• 제목/요약/키워드: Effective Shear Stress

검색결과 401건 처리시간 0.026초

CF8M 주조 스테인리스강의 2축 피로수명 예측을 위한 파라미터의 제안 (A Proposal of Parameter to Predict Biaxial Fatigue Life for CF8M Cast Stainless Steels)

  • 박중철;권재도
    • 대한기계학회논문집A
    • /
    • 제29권6호
    • /
    • pp.815-821
    • /
    • 2005
  • Biaxial low cycle fatigue test was carried out to predict fatigue life under combined axial-torsional-loading condition which is that of in-phase and out-of-phase for CF8M cast stainless steels. Fatemi-Socie(FS) parameter which is based on critical plane approach is not only one of methods but also the best method that can predict fatigue life under biaxial loading condition. But the result showed that, biaxial fatigue life prediction by using FS parameter with several different parameters for the CF8M cast stainless steels is not conservative but best results. So in this present research, we proposed new fatigue life prediction parameter considering effective shear stress instead of FS parameter which considers the maximum normal stress acting on maximum shear strain and its effectiveness was verified.

탄성유체 윤활상태와 접선하중을 고려한 접촉표면 내부의 응력해석 (Subsurface Stress Analysis with the Consideration of Tangential Loading and Elasto-Hydrodynamic Lubrication)

  • 구영필
    • Tribology and Lubricants
    • /
    • 제20권4호
    • /
    • pp.190-196
    • /
    • 2004
  • The effect of tangential loading on the subsurface stress field has been investigated numerically. As tangential load increases, the subsurface stress field expands more widely to the direction of the tangential load. Places of the maximum shear stress and the maximum effective stress are getting closer to the surface with the increasing tangential load. The tangential load in an elasto-hydrodynamic lubrication condition is so low that it does not affect the subsurface stress field.

Shear behavior of RC beams externally strengthened and anchored with CFRP composites

  • Al-Rousan, Rajai Z.
    • Structural Engineering and Mechanics
    • /
    • 제63권4호
    • /
    • pp.447-456
    • /
    • 2017
  • The primary objective of this paper is to study the effectiveness of anchorage on the performance of shear deficient beams externally strengthened with CFRP composites. The overall behavior of the tested beams loaded up to failure, the onset of the cracking, and crack development with increased load and ductility were described. The use of CFRP composites is an effective technique to enhance the shear capacity of RC beams by using CFRP strips anchored into the tension side and from the top by 15-34% based on the investigated variables. Bonded anchorage of CFRP strips with width of 0.1h-0.3h to the beam resulted in a decrease in average interface bond stress and an increase in the effective strain of the FRP sheet at failure, which resulted in a higher shear capacity as compared with that of the U-wrapped beams without anchorage as well as delay or mitigate the sheet debonding from the concrete surface.

Embedded type new in-situ soil stiffness assessment and monitoring technique

  • Namsun Kim;Jong-Sub Lee;Younggeun Yoo;Jinwook Kim;Junghee Park
    • Smart Structures and Systems
    • /
    • 제34권1호
    • /
    • pp.33-40
    • /
    • 2024
  • We aimed to assess the evolution of small-strain stiffness and relative density in non-compacted embankment layers. We developed embedded type in-situ soil stiffness measurement devices for monitoring small-strain stiffness occurring after filling at a test site and conducted comprehensive laboratory compaction tests using an oedometer cell with a bender element. However, direct comparison is extremely difficult because the shear wave velocity measured in the field and laboratory depend on depth and effective stress, respectively. Therefore, we propose a method for establishing a relationship between effective stress and depth using a compressibility model. In this study, the shear wave velocity measured in the field was compared to the estimated shear wave velocity-depth profiles for completely dry and saturated conditions with different relative densities. The relative density under saturated soil conditions may vary between 50% and 90% and tends to be closer to 95%. Under dry soil conditions, the relative density of the embankment can vary from 30% to 70% and tends to approach 76%. For model validation, the relative density estimated from shear wave velocity-depth profiles was compared to that estimated from DCPI data. In other words, the results analyzed in the context of an effective stress-depth model enable the prediction of engineering properties such as the small-strain stiffness and relative density of embankment layers. This study demonstrates that physics-based data analyses successfully capture the relative density of non-compacted embankment layers.

재구성 시료의 일축압축시험에서 유효응력경로를 이용한 원지반의 비배수 전단강도 추정에 관한 연구 (A Study on the Estimation of In-situ Undrained Shear Strength Using Effective Stress Paths of Reconstituted Sample by Unconfined Compression Test)

  • 박성재;오원택;정경환;여주태
    • 한국지반공학회논문집
    • /
    • 제19권1호
    • /
    • pp.93-102
    • /
    • 2003
  • 일축압축시험은 방법이 비교적 간단하고 경제적이기 때문에 점토지반의 비배수 전단강도($c_u$)를 결정하는데 널리 사용되고 있다. 하지만, 구속압이 없는 상태에서 시험이 시행되기 때문에 지중응력 조건을 재현할 수 없고, 또한 삼축압축시험에 의한 강도보다 과소평가 되는 경우가 많다. 따라서, $c_u$를 시료교란에 대해 보정하여 실무에서 간단히 사용할 수 있는 강도 보정법이 요구된다. 본 연구에서는 흡수력 측정을 겸한 일축압축시험 만으로 원지반의 비배수 전단강도(이하, 원지반 강도)를 추정할 수 있는 방법을 제시하고자 한다. 제안된 방법은 완전시료의 이론적 전단강도식(Noorany와 Seed, 1965)을 기본으로 하며, 유효토피압과 일축압축시험의 유효응력거동 분석 결과( $A_f,\phi'$)를 필요로 한다. 특히, 전단저항각($\phi'$)은 일축압축시험의 수정파괴포락선($K_f$) 기울기가 삼축압축시험에 비해 약 1.6배정도 더 크게 평가된다는 시험결과를 근거로 하여 간단히 유추할 수 있다. 연구 결과, 제안된 방법에 의해 추정된 원지반 강도는 삼축압축시험(CK$_0$UC)의 비배수 전단강도와 유사한 값을 나타냈다.

전단 대변형을 고려한 유연직물복합재료 해석 (Analysis of Flexible Textile Composites with Large Shear Deformation)

  • 서영욱;우경식;강왕구
    • 한국항공우주학회지
    • /
    • 제36권8호
    • /
    • pp.734-739
    • /
    • 2008
  • 본 논문에서는 미시 및 중시 역학의 2-단계 해석 전략을 채택하여 유연직물 복합재료의 기계적 거동을 예측하였다. 미시역학에서는 섬유다발의 유효물성치를 계산하였고 그 결과를 이용해 중시역학에서 유연직물복합재료의 인장탄성계수를 예측하였다. 중시역학 해석 과정에서는 섬유다발의 회전 및 전단 대변형에 의한 기하학적 비선형성을 고려하기 위하여 사용자 정의 부프로그램을 개발하여 ABAQUS 내에 삽입하였다. 해석결과, 인장하중을 받는 유연직물복합재료의 응력-변형률은 비선형 거동을 보였고, 계산된 유효탄성계수는 시험값과 잘 일치하는 것으로 나타났다.

피라미드 형상의 PCM 코어 단위 셀의 압축 및 전단특성에 관한 해석적 연구 (Analytical Approach to Compression and Shear Characteristics of the Unit Cell of PCM Core with Pyramidal Configuration)

  • 김상우;정현철;이영선;강범수
    • 소성∙가공
    • /
    • 제19권7호
    • /
    • pp.411-415
    • /
    • 2010
  • A sandwich panel which is comprised of truss cores faced with solid face sheets is lightweight and multi-functional. So it is widely used to not only structural material but also heat transfer media in transportation field such as airplane, train and vessel. There are various core topologies such as pyramidal and tetrahedral truss, square honeycombs and kagome truss. The study focused on analytical approach to optimize compression and shear quality of the unit cell of PCM with pyramidal configuration. With various unit cell models which have the same core weight per unit area but different truss member angle, analytical solution for effective stress ($\bar{\sigma},\bar{\tau}$), peak stress ($\bar{\sigma}_{peak},\bar{\tau}_{peak}$) by yielding and buckling, relative density ($\bar{\rho}_c$) and effective stiffness ($\bar{E},\bar{G}$) have been computed and compared each other. With this approach, the most optimal core configuration was predicted. The result has become the efficient guidelines for the design of PCM core structure.

Tractive performance evaluation of seafloor tracked trencher based on laboratory mechanical measurements

  • Wang, Meng;Wang, Xuyang;Sun, Yuanhong;Gu, Zhimin
    • International Journal of Naval Architecture and Ocean Engineering
    • /
    • 제8권2호
    • /
    • pp.177-187
    • /
    • 2016
  • To evaluate the tractive performance of tracked trencher on seafloor surface, a new shear stress-displacement empirical model was proposed for saturated soft-plastic soil (SSP model). To validate the SSP model, a test platform, where track segment shear test can be performed in seafloor soil simulacrum (bentonite water mixture), was built. Series shear tests were carried out. Test results indicate that the SSP model can describe the mechanical behavior of track segment with good approximation in seafloor soil simulacrum. Through analyzing the main external forces applied to seafloor tracked trencher during the uniform linear trenching process, a drawbar pull prediction model was deduced with the SSP model. A tracked walking mechanism of the seafloor tracked trencher prototype was built, and verification tests were carried out. Test results indicate that this prediction model was feasible and effective; moreover, from another side, this conclusion also proved that the SSP model was effective.

공진주 시험기 단부가 압밀중인 시료의 유효응력에 미치는 영향 (The effects of End Platens on Effective Stresses in Resonant Column (RC) Specimens during Consolidation)

  • 배윤신
    • 한국지진공학회논문집
    • /
    • 제12권1호
    • /
    • pp.29-42
    • /
    • 2008
  • 이번 연구의 목적은 시험기의 단부가 압밀중인 시료의 유효응력에 미치는 영향을 연구함에 있다. 압밀중에 시험기 단부와 시료사이의 마찰은 공진주 시험기 시료의 반경 및 접선방향의 유효응력을 감소시킨다. 하지만, 시료의 유효응력을 측정하는 것은 실용적이지 않다. 압밀중 시험기 시료 유효응력 상태를 평가하기 위해 두 가지 접근이 이루어졌다. 첫째, 응력상태를 추측하기 위해 신중하게 조절된 간극비와 응력이력을 가진 시료의 최대 전단 탄성계수가 측정되었다. 둘째, 여러 가지 시료 정수가 압밀중 시험기 시료의 응력상태에 미치는 영향을 분석하기 위해 유한요소법이 수행되었다. 이러한 실험 결과와 분석적 기법결과를 종합해서 압밀중 공진주 시험시료에서의 평균주응력을 예측하는 해석적 예제를 수행하였다.

고강도 철근콘크리트 춤이 큰 보의 전단스팬비 효과 (The Effect of Shear Span-to-Effective Depth Ratio of Reinforced high Strength Concrete Deep Beam)

  • 오정근;성열영;안종문;이광수;신성우
    • 콘크리트학회지
    • /
    • 제9권5호
    • /
    • pp.225-231
    • /
    • 1997
  • 콘크리트 압축강도 및 전단스팬비의 변화에 의한 고강도 철근콘크리트 춤이 큰 보의 전단거동 및 내력특성을 파악하기 위한 실험적 연구를 하였다. 춤이 큰 보는 하중작용점과 하중지지점을 연결하는 사균열의 확대에 의해 취성전단파괴양상을 나타내었으며 하중작용점 하중 지지점의 콘크리트 압괴를동반하는 전단압축 및 전단인장파괴 형태로 최종파괴되었다. 전단스팬비가 감소함에 따라 사균열전단응력 및 최대전단응력은 크게 증가하였으며, ACI 및 CIRIA규준식은 부재의 최대전단응력을 비교적 정확하게 예측하고 있음을 파악하였다.