• Title/Summary/Keyword: 임계하중

Search Result 80, Processing Time 0.551 seconds

Elastic stability analysis of curved steel rib using differential quadrature method (DQM) (미분 구적법 (DQM)을 이용한 곡선 강지보의 안정성 해석)

  • Kang, Ki-Jun;Kim, Byeong-Sam;Kim, Sang-Hwan
    • Journal of Korean Tunnelling and Underground Space Association
    • /
    • v.6 no.4
    • /
    • pp.279-290
    • /
    • 2004
  • The differential quadrature method (DQM) for a system of coupled differential equations governing the elastic stability of thin-walled curved members is presented, and is applied to computation of the eigenvalues of out-of-plane buckling of curved beams subjected to uniformly distributed radial loads including a warping contribution. Critical loads with warping, which were found to be significant, are calculated for a single-span wide-flange beam with various end conditions, opening angles, and stiffness parameters. The results are compared with the exact methods available. New results are given for the case of both ends clamped and clamped-simply supported ends without comparison since no data are available The differential quadrature method gives good accuracy and stability compared with previous theoretical results.

  • PDF

Surface structure and critical load of thin metal films on SiC substrate (SiC 기판상의 금속박막의 표면구조 및 임계하중)

  • 임창성
    • Journal of the Korean Crystal Growth and Crystal Technology
    • /
    • v.5 no.4
    • /
    • pp.358-369
    • /
    • 1995
  • Surface structure and adhesion by the reaction between thin metal films and SiC were studied at temperatures between 550 and $1450^{\circ}C$ for various times. The reaction with the formation of various silicides was initially observed above $850^{\circ}C$ for SiC/Co system and $650^{\circ}C$ for SiC/Ni system. The cobalt reacted with SiC and consumed completely at $1050^{\circ}C$ for 0.5 h and the nickel at $950^{\circ}C$ for 2 h. The observed CoSi phase in SiC/Co and Ni$_2$Si phase in SiC/Ni are thermodynamically stable in the reaction zone up to 125$0^{\circ}C$ and $1050^{\circ}C$ respectively. Carbon was crystallized as graphite above $1450^{\circ}C$ for SiC/Co reaction surface and $1250^{\circ}C$ for SiC/Ni. The critical loads of the thin metal films on SiC substrate were qualitatively compared in terms of the scratch test method. At temperatures between 850 and $1050^{\circ}C$, relatively higher values of 20~33 N were observed for SiC/Ni couples.

  • PDF

A Study on Dynamic Stability Regions for Parabolic Shallow Arches (낮은 포물선(抛物線) 아치의 동적(動的) 안정영역(安定領域)에 관한 연구(硏究))

  • Park, Kwang Kyou;Kim, Moon Kyum;Hwang, Hak Joo
    • KSCE Journal of Civil and Environmental Engineering Research
    • /
    • v.6 no.3
    • /
    • pp.1-9
    • /
    • 1986
  • Dynamic stability of parabolic shallow arches, which are supported by hinges at both ends, is investigated. The Runge-Kutta method is used to perform time integrations of the differential equations of motion with proper boundary conditions. Based on Budiansky-Roth criterion, dynamic critical load combinations are evaluated numerically for cases of step loads of infinite duration and impulse loads, individually. The results are plotted to get interaction curves. The loci of the dynamic critical loads, which are obtained in this study, are proposed as boundaries between the dynamic stability and instability regions for the parabolic shallow arches. The results for the parabolic shallow arches are also compared with those for sinusoidal arches of the same arch rises. According to the investigation, the dynamic stability regions for the parabolic arches are larger than those for the sinusoidal arches. However, it is shown that the arch rise is the more governing factor than the shape.

  • PDF

The Dynamic Buckling and Critical Load of the Spatial Truss under the Beating-wave Load (맥놀이하중을 받는 공간구조물의 동적좌굴과 임계하중)

  • Ha, Jun-Hong;Shon, Su-Deok;Lee, Seung-Jae
    • Journal of the Architectural Institute of Korea Structure & Construction
    • /
    • v.32 no.7
    • /
    • pp.23-31
    • /
    • 2016
  • In this study, the dynamic unstable phenomenon and critical load variation of the spatial truss under the beating-wave load were researched. For this purpose, a non-linear governing equation of a shallow spatial truss was derived. In addition, a dynamic analysis and a characteristic analysis of the buckling phenomenon were conducted using the numerical method. The analysis model was selected considering the number of free nodes and the rise-span ratio, and the response to the periodic parameter that determines the period of the beating function was analyzed. To compare the results, a analysis for the step load and sinusoidal-wave load were also conducted. Resonance was observed in the analysis results for both the sinusoidal-wave load and the beating-wave load. The patterns of critical load level were similar in the area lower than the natural frequency, but they were different in the area above it. Furthermore, the critical level of the beating-wave load changed more sensitively than the sinusoidal-wave load did and was much lower than the step load.

The Elastic Critical Loads of Sinusolidally Tapered Symmetric Compression Members (정현상 대칭으로 Taper진 변단면 압축재의 임계하중)

  • 오금열;홍종국;김순철;이수곤
    • Proceedings of the Computational Structural Engineering Institute Conference
    • /
    • /
    • pp.27-34
    • /
    • 2000
  • The elastic critical loads of prismatic compression members can be easily determined by the conventional analytic method. In the cases of sinusoidally tapered members, however, the determination of elastic critical loads become impossible when one relies on the analytic method. In this paper, the critical loads of sinusoidally tapered members were determined by finite element method. Generally the output or results of numerical analysis are valid only when the governing parameters of a given system(or problem) have particular values. To make the practical applications easy, the critical loads determined by finite element method are expressed by some algebraic equations. The constants contained in the algebraic equations were determined by regression technique. The elastic critical loads estimated by the proposed algebraic equations coincide well with those by finite element method.

  • PDF

Lateral Vibration and Elastic Stability of Rectangular Plates with Cutouts (개구부를 가진 직사각형 평판구조의 진동 및 안정성 해석)

  • 이수곤;김순철;박근흥
    • Computational Structural Engineering
    • /
    • v.3 no.2
    • /
    • pp.77-88
    • /
    • 1990
  • Two perforated plates (a square plate and a rectangular plate having an aspect ratio 1.57(L/sub x/=11, L/sub y/=7)) are taken as analysis examples. Each of these plates is given some changes in the boundary conditions. The size of cutouts as well as their locations are also changed in order to examine the variation of two eigenvalues corresponding to the fundamental mode. The relationship between two eigenvalues is established by changing the magnitude of edge thrust.

  • PDF

Estimation of fully plastic crack tip stresses of unequally notched specimen under bending and tension (굽힘 모멘트와 인장 하중이 작용하는 비대칭 노치 시편의 완전 소성 균열 선단 응력의 예측)

  • Oh, Chang-Kyun;Kim, Yun-Jae;Park, Jin-Moo
    • Proceedings of the KSME Conference
    • /
    • /
    • pp.37-42
    • /
    • 2004
  • This paper presents a simple method to estimate fully plastic crack tip stresses of unequally notched specimen based on the equilibrium condition of the least upper bounds for plane strain deformation fields. The method is applied to unequally notched specimens under bending and tension. For various notch angle the limit loads and crack tip stresses are estimated from the present method and compared with results from finite element limit analyses.

  • PDF

Stability of Stepped Columns Subjected to Nonconservative Force (비보존력이 작용하는 불연속 변단면 기둥의 안정성)

  • Oh, Sang-Jin;Mo, Jeong-Man;Lee, Jae-Young
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • /
    • pp.801-804
    • /
    • 2006
  • The purpose of this paper is to investigate the stability of stepped cantilever columns with a tip mass of rotatory inertia and a translational spring at one end. The column model is based on the Bernoulli-Euler theory which neglects the effects of rotatory inertia and shear deformation. The governing differential equation for the free vibration of columns with stepwise variable cross-section and subjected to a subtangential follower force is solved numerically using the corresponding boundary conditions. And the bisection method is used to calculate the critical divergence/flutter load. The frequency and critical divergence/flutter load for the stepped column with a single step are presented as functions of various non-dimensional system parameters: the segmental length parameter, the section ratio, the subtangential parameter, the mass, the moment of inertia of the mass, and the spring parameter.

  • PDF

Elastic Critical Loads of Rectangular Plates Under Patch toads (부분 분포하중이 재하된 직4각형 평판의 임계하중)

  • Lee, Soo-Gon;Kim, Soon-Chul;Song, Yong-Yuk;Song, Sang-Yong
    • Proceedings of the Computational Structural Engineering Institute Conference
    • /
    • /
    • pp.549-556
    • /
    • 2002
  • 주변이 Kinney의 정의에 따른 부분 고정도를 가지고 지지된 직4각형 평판이 부분 분포하중을 받고 있을 때의 안정해석을 유한 요소법으로 수행하였다. 수치해석에서 고려한 변수는 평판의 변장비 (=λ)와 부분 분포하중 작용폭 (=γ) 및 부분 고정도 (=f) 값이다. 여기서 특히 f=0.0 은 주변이 단순지지를 표시하고 f=1.0은 고정지지를 뜻하는데 수치해석에서는 f=0.0, 0.2, …, 1.0으로 변화시켰다. 유한 요소법으로 산정한 판의 좌굴계수 변화는 각각의 변장비에 대하여 나머지 두 개의 매개변수를 변랑으로 하는 대수 함수식으로 표시하였다. 제안한 대수식으로 추정한 임계하중치와 유한 요소법으로 산정한 임계하중치 간의 상관계수는 모든 변장비에 대하여 거의 단위치 (ρ=1.0)에 가까웁다. 따라서 제안한 대수 함수식은 구조 설계자들의 판 설계 및 안정 검토시에 유익한 자료로 이용될 수 있다.

  • PDF

Elastic Critical Load of Tapered Columns (변단면 압축재의 임계하중)

  • 김태순;홍종국;김순철;이수곤
    • Proceedings of the Computational Structural Engineering Institute Conference
    • /
    • /
    • pp.421-428
    • /
    • 1999
  • The elastic critical load of a slender compression member plays an important role when the proper design of that member is required. For the tapered compression members, however, there are cases when the conventional neutral equililbrium or energy method can't be applied to the determination of critical loads of those members. In this paper, finite element method is applied to the approximate determination of the symmetrically tapered bars. Here in this paper, the bars are assumed to take sinusoidally changing shapes along their axes. The parameters considered in this study are taper parameter, $\alpha$ and the sectional property parameter, m. The computed results by finite element method are represented in the forms of algebraic equations. Regression technique is employed to determine the coefficients of algebraic equations. The critical loads estimated by the proposed algebraic equations coincide fairly well with those of finite element method.

  • PDF