• 제목/요약/키워드: Beam Factor

검색결과 1,017건 처리시간 0.03초

철골 연성 모멘트 골조에 대한 다자유도 시스템의 연성계수 평가 (Evaluation of Ductility Factors for MDOF Systems in Special Steel Moment Resisting Frames)

  • 강철규;한영철
    • 한국지진공학회논문집
    • /
    • 제8권6호통권40호
    • /
    • pp.13-22
    • /
    • 2004
  • 연성 계수는 반응수정계수(R)의 핵심구성요소로서 내진설계에서 중요한 역할을 하는 계수이다. 본 연구에서의 연성계수()는 단자유도 구조물의 연성계수()에 다자유도 보정계수()를 곱하여 평가하였다. 단자유도 시스템의 연성계수는 지진하중을 받는 단자유도 구조물의 변위 연성요구도와 주기에 따른 비선형 동적해석으로부터 산정하였다. 다자유도 시스템의 영향을 고려하기 위한 다자유도 보정계수()는 기존의 연구에 근거하여 제시하였다. 철골 연성 모멘트 골조의 연성계수를 평가하기 위하여, 구조물의 층수, 골조시스템(외곽골조, 분배골조), 붕괴 메카니즘(강-기둥 약-보, 약-기둥 강-보), 토질조건 및 지진구역을 변수로 하여 총 108개의 예제 구조물을 설계하였다. 구조물의 층수, 붕괴 메카니즘 및 토질조건은 연성계수에 큰 영향을 미치는 반면, 골조 시스템 및 지진구역은 연성계수에 영향을 미치지 않는 것으로 나타났다.

Complex modes in damped sandwich beams using beam and elasticity theories

  • Ahmad, Naveed;Kapania, Rakesh K.
    • Advances in aircraft and spacecraft science
    • /
    • 제2권1호
    • /
    • pp.57-76
    • /
    • 2015
  • We investigated complex damped modes in beams in the presence of a viscoelastic layer sandwiched between two elastic layers. The problem was solved using two approaches, (1) Rayleigh beam theory and analyzed using the Ritz method, and (2) by using 2D plane stress elasticity based finite-element method. The damping in the layers was modeled using the complex modulus. Simply-supported, cantilever, and viscously supported boundary conditions were considered in this study. Simple trigonometric functions were used as admissible functions in the Ritz method. The key idea behind sandwich structure is to increase damping in a beam as affected by the presence of a highly-damped core layer vibrating mainly in shear. Different assumptions are utilized in the literature, to model shear deformation in the core layer. In this manuscript, we used FEM without any kinematic assumptions for the transverse shear in both the core and elastic layers. Moreover, numerical examples were studied, where the base and constraining layers were also damped. The loss factor was calculated by modal strain energy method, and by solving a complex eigenvalue problem. The efficiency of the modal strain energy method was tested for different loss factors in the core layer. Complex mode shapes of the beam were also examined in the study, and a comparison was made between viscoelastically and viscously damped structures. The numerical results were compared with those available in the literature, and the results were found to be satisfactory.

Effect of high-energy neutron source on predicting the proton beam current in the ADS design

  • Zheng, Youqi;Li, Xunzhao;Wu, Hongchun
    • Nuclear Engineering and Technology
    • /
    • 제49권8호
    • /
    • pp.1600-1609
    • /
    • 2017
  • The accelerator-driven subcritical system (ADS) is driven by a neutron source from spallation reactions introduced by the injected proton beam. Part of the neutron source has energy as high as a few hundred MeV to a few GeV. The effects of high-energy source neutrons ($E_n$ > 20 MeV) are usually approximated by energy cut-off treatment in practical core calculations, which can overestimate the predicted proton beam current in the ADS design. This article intends to quantize this effect and propose a way to solve this problem. To evaluate the effects of high-energy neutrons in the subcritical core, two models are established aiming to cover the features of current experimental facilities and industrial-scale ADS in the future. The results show that high-energy neutrons with $E_n$ > 20 MeV are of small fraction (2.6%) in the neutron source, but their contribution to the source efficiency is about 23% for the large scale ADS. Based on this, a neutron source efficiency correction factor is proposed. Tests show that the new correction method works well in the ADS calculation. This method can effectively improve the accuracy of the prediction of the proton beam current.

Design of a Beam-coupling System for a Chip-integrated Spectrometer with a Discrete Linear Waveguide

  • Liu, Zhiying;Jiang, Xin;Li, Mingyu
    • Current Optics and Photonics
    • /
    • 제4권3호
    • /
    • pp.229-237
    • /
    • 2020
  • In this study, a beam-coupling system is designed to improve the coupling efficiency of achip-integrated spectrometer when the waveguide is arranged in a linear and discrete manner. In the proposed system the beam is shaped to be anti-Gaussian, to deposit adequate energy in the edge waveguides. The beam is discretely coupled to the corresponding waveguide by a microlens array, to improve the coupling efficiency, and is compressed by a toroidal lens to match the linear discrete waveguides. Based on the findings of this study, the coupling efficiency of the spectrometer is shown to increase by a factor of 2.57. Accordingly, this study provides a reference basis for the improvement of the coupling efficiency of other similar spectrometers.

불규칙 이동분포하중을 받는 타이어의 구조 진동 소음 제어를 위한 음향방사 해석 (Sound Radiation Analysis for Structural Vibration Noise Control of Tire Under the Action of Random Moving Line Forces)

  • 김병삼;이성철
    • 소음진동
    • /
    • 제5권2호
    • /
    • pp.169-181
    • /
    • 1995
  • A theoretical model has been studied to describe the sound radiation analysis for structural vibration noise control of tire under the action of random moving line forces. When a tire is analyzed, it has been modeled as a curved beam with distributed springs and dash-pots which represent the radial, tangential stiffness and damping of tire, respectively. The reaction due to fluid loading on the vibratory response of the curved beam is taken into account. The curved beam is assumed to occupy the plane y = 0 and to be axially infinite. The material of curved beam and elastic foundation are assumed to be lossless, and governed by the law of Bernoulli-Euler beam theory. The expression for sound power is integrated numerically and its results examined as a function of Mach number(M), wavenumber ratio(.gamma.) and stiffness factor(.PSI.). The experimental investigation for structural vibration noise of tire under the action of random moving line forces has been made. Based on the STSF(Spatial Transformation of Sound Field) techniques, the sound power and sound radiation are measured. The experimental results show that operating condition, material properties and design factors of the tire have a great effect on the sound power and sound radiation characteristics.

  • PDF

Buckling and free vibration analyses of nanobeams with surface effects via various higher-order shear deformation theories

  • Rahmani, Omid;Asemani, S. Samane
    • Structural Engineering and Mechanics
    • /
    • 제74권2호
    • /
    • pp.175-187
    • /
    • 2020
  • The theories having been developed thus far account for higher-order variation of transverse shear strain through the depth of the beam and satisfy the stress-free boundary conditions on the top and bottom surfaces of the beam. A shear correction factor, therefore, is not required. In this paper, the effect of surface on the axial buckling and free vibration of nanobeams is studied using various refined higher-order shear deformation beam theories. Furthermore, these theories have strong similarities with Euler-Bernoulli beam theory in aspects such as equations of motion, boundary conditions, and expressions of the resultant stress. The equations of motion and boundary conditions were derived from Hamilton's principle. The resultant system of ordinary differential equations was solved analytically. The effects of the nanobeam length-to-thickness ratio, thickness, and modes on the buckling and free vibration of the nanobeams were also investigated. Finally, it was found that the buckling and free vibration behavior of a nanobeam is size-dependent and that surface effects and surface energy produce significant effects by increasing the ratio of surface area to bulk at nano-scale. The results indicated that surface effects influence the buckling and free vibration performance of nanobeams and that increasing the length-to-thickness increases the buckling and free vibration in various higher-order shear deformation beam theories. This study can assist in measuring the mechanical properties of nanobeams accurately and designing nanobeam-based devices and systems.

일축 대칭 I 형 보의 모멘트 구배계수에 대한 연구 (A Study on the Moment Gradient factor of Mono-symmetric I Beam)

  • 김윤종;임남형;박남회;강영종
    • 한국철도학회:학술대회논문집
    • /
    • 한국철도학회 2000년도 춘계학술대회 논문집
    • /
    • pp.439-446
    • /
    • 2000
  • 본 연구에서는 절점당 7자유도(뒤틀림 자유도 포함)를 갖는 보요소를 개발하여, 와그너 효과(Wagner Effect) 및 하중고 효과(Load Height Effect)가 일축 대칭 I 형보의 횡좌굴 강도에 미치는 영향을 파악하였다. 하중의 종류는 단면내 다양한 높이에 작용하는 횡방향 하중과 선형 모멘트 구배하중을 고려하였으며, 이들 하중에 의한 비지지 길이내 단일곡률의 휨과 역의 곡률의 휨이 생길때의 좌굴해석을 수행하였다. 현행 LRFD $C_{b}$ 계수의 일축 대칭 I 형 보에의 적용성을 검토하였으며, 하중고 효과(Load height effect) 및 비지지 길이내 역의 곡률(Reverse curvature bending) 발생시에 생기는 문제점들을 고찰해 보고, 해결방안을 제시하였다.

  • PDF

A mechanical response of functionally graded nanoscale beam: an assessment of a refined nonlocal shear deformation theory beam theory

  • Zemri, Amine;Houari, Mohammed Sid Ahmed;Bousahla, Abdelmoumen Anis;Tounsi, Abdelouahed
    • Structural Engineering and Mechanics
    • /
    • 제54권4호
    • /
    • pp.693-710
    • /
    • 2015
  • This paper presents a nonlocal shear deformation beam theory for bending, buckling, and vibration of functionally graded (FG) nanobeams using the nonlocal differential constitutive relations of Eringen. The developed theory account for higher-order variation of transverse shear strain through the depth of the nanobeam, and satisfy the stress-free boundary conditions on the top and bottom surfaces of the nanobeam. A shear correction factor, therefore, is not required. In addition, this nonlocal nanobeam model incorporates the length scale parameter which can capture the small scale effect and it has strong similarities with Euler-Bernoulli beam model in some aspects such as equations of motion, boundary conditions, and stress resultant expressions. The material properties of the FG nanobeam are assumed to vary in the thickness direction. The equations of motion are derived from Hamilton's principle. Analytical solutions are presented for a simply supported FG nanobeam, and the obtained results compare well with those predicted by the nonlocal Timoshenko beam theory.

돼지 간중의 Monooxygenase 가 Diazinon 의 분해에 미치는 영향 (The degradation o Diazinon by hepatic monooxygenase of Pig)

  • 류종국;이규승
    • 한국환경농학회지
    • /
    • 제9권2호
    • /
    • pp.153-159
    • /
    • 1990
  • 돼지간을 두 fraction($105,000{\time}g$ pellet, superatant)으로 나누어 Diazinon의 분해에 관여하는 두 효소(Monooxygenase와 esterase)의 활성 및 저해제(EPN, Beam, PBO)첨가에 따른 Diazinon의 분해억제 능력을 비교 검토하였다. 1. 돼지간의 microsomal fraction과 soluble fraction에서 M. O.와 β-esterase 활성은 20분과 60분에 최고활성을 나타내었다. 2. Microsomal fraction에서의 M. O.활성은 NADPH generating system의 첨가로 1.6배의 활성증가와 지속성이 확인되었다. 3. Microsomal fraction에서의 Diazinon분해량은 30분에 최고량(0.060nM/ mg/ min)을 보였으나, soluble fraction에서는 60분에 최고량(0.018nM/ mg/ min)을 보여 1/3수준이었다. 4. M. O.활성에 미치는 Diazinon에 대한 EPN, Beam, PBO의 첨가효과는 Beam(14%)< EPN(15%)

  • PDF

고유치 해석을 이용한 보의 크랙 탐색 (Detection of a Crack in Beams by Eigen Value Analysis)

  • 이희수;이기훈;최재훈
    • EDISON SW 활용 경진대회 논문집
    • /
    • 제5회(2016년)
    • /
    • pp.195-202
    • /
    • 2016
  • In this paper, crack detection method using eigen value analysis is presented. Three methods are used: theoretical analysis, finite element method with the cracked beam elements and finite element method with three dimensional continuum elements. Finite element formulation of the cracked beam element is introduced. Additional term about stress intensity factor based on fracture mechanics theory is added to flexibility matrix of original beam to model the crack. As using calculated stiffness matrix of cracked beam element and mass matrix, natural frequencies are calculated by eigen value analysis. In the case of using continuum elements, the natural frequencies could be calculated by using EDISON CASAD solver. Several cases of crack are simulated to obtain natural frequencies corresponding the crack. The surface of natural frequency is plotted as changing with crack location and depth. Inverse analysis method is used to find crack location and depth from the natural frequencies of experimental data, which are referred by another papers. Predicted results are similar with the true crack location and depth.

  • PDF