• Title/Summary/Keyword: Bucking analysis

Search Result 56, Processing Time 0.024 seconds

An Analysis of the Operational Time and Productivity in Whole-tree and Cut-to-Length Logging Operation System (전목 및 단목 집재작업시스템에서 작업시간 및 공정 분석)

  • Kim, Min-Kyu;Park, Sang-Jun
    • Journal of Korean Society of Forest Science
    • /
    • v.101 no.3
    • /
    • pp.344-355
    • /
    • 2012
  • This study was conducted to analyze on the operational time and productivities of logging operations in whole-tree logging operation system by tower-yarder and swing-yarder, and in cut-to-length logging operation system by excavator with grapple in order to establish the efficient logging operation system and to spread logging operation technique. In the analysis of operational time, in case of whole-tree logging operation system, the felling time was 46.6 sec/cycle by chain saw, the yarding time was 480.6 sec/cycle by tower-yarder, the yarding time was 287.4 sec/cycle by swing-yarder and the bucking time was 155.14 sec/cycle by chain saw. In case of the cut-to-length logging operation system, the felling and bucking time was 225.65 sec/cycle by chain saw, the cut-to-length extraction time was 4,972 sec/cycle by excavator with grapple, the branches and leaves extraction time was 3,143 sec/cycle by excavator with grapple. The forwarding time was 4,688 sec/cycle by wheel type mini-forwarder, the forwarding time was 2,118 sec/cycle by excavator with grapple and small forwarding vehicle. In the analysis of operational productivities, in case of whole-tree logging operation system, the average felling performance was $57.89m^3/day$ by chain saw, the average yarding performance was $20.3m^3/day$ by tower-yarder, $31.55m^3/day$ by swing-yarder respectively, the average bucking performance was $20.3m^3/day$ by chain saw. In case of the cut-to-length logging operation system, the average felling and bucking performance was $11.96m^3/day$ by chain saw, the average cut-to-length extraction performance was $34.75m^3/day$ by excavator with grapple, the average branches and leaves extraction performance was $37.66m^3/day$ by excavator with grapple, the average length of operation road construction was 73.8 m/day by excavator with grapple. The average forwarding performance by wheel type mini-forwarder and the average forwarding performance by excavator with grapple and small forwarding vehicle was $15.73m^3/day$ and $65.03m^3/day$, respectively.

Evaluation of Seismic Buckling Load for Seismically Isolated KALIMER Reactor Vessel (면진설계된 KALIMER 원자로용기의 지진좌굴 특성평가)

  • 구경회
    • Proceedings of the Earthquake Engineering Society of Korea Conference
    • /
    • 1999.10a
    • /
    • pp.220-227
    • /
    • 1999
  • The Purpose of this paper is to evaluate the buckling strength of conceptually designed KALIMER reactor vessel. For evaluation of the buckling load buckling load the design equations and the finite element analysis are used. In finite element method the eigenvalue buckling analysis nonlinear elastic buckling analysis using snap-through buckling method and nonlinear elastic-plastic buckling analysis are carried out. the calculated buckling loads of KALIMER reactor vessel using the finite element method are in well agreement with those of the design equations. From the calculated results of buckling load in KALIMER rector vessel it is shown that the plasticity of vessel materials significantly affects the buckling load but the initial imperfection has little effects, In checking the limits of bucking load of KALIMER reactor vessel using the ASME B & PV Section III. Subsection NH the non-seismic isolation design can not satisfy the buckling limit requirements but the seismic isolation design can sufficiently satisfy the requirements.

  • PDF

Effects of initial imperfections on nonlinear behaviors of thin-walled members

  • Ohga, M.;Takaue, A.;Shigematsu, T.;Hara, T.
    • Structural Engineering and Mechanics
    • /
    • v.11 no.5
    • /
    • pp.519-534
    • /
    • 2001
  • The effect of the initial imperfections on the nonlinear behaviors and ultimate strength of the thin-walled members subjected to the axial loads, obtained by the finite element stability analysis, are examined. As the initial imperfections, the bucking mode shapes of the members are adopted. The buckling mode shapes of the thin-walled members are obtained by the transfer matrix method. In the finite element stability analysis, isoparametric degenerated shell element is used, and the geometrical and material nonlinearity are considered based on the Green Lagrange strain definition and the Prandtl-Reuss stress-strain relation following the von Mises yield criterion. The U-, box- and I-section members subjected to the axial loads are adopted for numerical examples, and the effects of the initial imperfections on the nonlinear behaviors and ultimate strength of the members are examined.

Modal Analysis of Sandwich Plate Structure Considering Bucking (좌굴을 고려한 샌드위치형 판 구조물의 모드해석)

  • 한근조;안찬우;안성찬;홍도관;한동섭
    • Proceedings of the Korean Society of Precision Engineering Conference
    • /
    • 1997.10a
    • /
    • pp.702-705
    • /
    • 1997
  • Sandwich plate structure is widely used in various fields of industry due to its excellent strength and stiffness compared with weight. In this paper, the mechanical behavior of sandwich plate structure with honeycomb core considering buckling is investigated in detail. The focus of the analysis is to evaluate strength and stiffness of the plate structure with critical stress, natural frequency, and mode shapes. The results of this investigation are obtained from detailed finite element analysis for various parameters, such as length, height ratio, and thickness ratio of honeycomb core

  • PDF

Ultimate load capacity of unit Strarch frames using an explicit numerical method

  • Lee, Kyoungsoo;Hong, Jung-Wuk;Han, Sang-Eul
    • Steel and Composite Structures
    • /
    • v.13 no.6
    • /
    • pp.539-560
    • /
    • 2012
  • This study uses an explicit numerical algorithm to evaluate the ultimate load capacity analysis of a unit Strarch frame, accounting for the initial imperfection effects of the stress-erection process. Displacement-based filament beam element and an explicit dynamic relaxation method with kinetic damping are used to achieve the analysis. The section is composed of the finite number of filaments that can be conveniently modeled by various material models. Ramberg-Osgood and bilinear kinematic elastic plastic material models are formulated to analyze the nonlinear material behaviors of filaments. The numerical results obtained in the present study are compared with the results of experiment for stress-erection and buckling of unit Strarch frames.

A Study on the Stress Analysis and Parameters of Bucking in Spherical Shell (반 구형 각의 좌굴현상에 대한 응력해석 및 영향인자에 관한 연구)

  • Kim, Yeong-Su;An, Du-Seong
    • Journal of the Korean Society of Fisheries and Ocean Technology
    • /
    • v.21 no.2
    • /
    • pp.142-150
    • /
    • 1985
  • In this paper, stress distribution were given in consideration of bending effects in hemi-spherical shell and a modified equation of buckling load was represented with implicating the effects of plastic deformations and shape parameters. Especially, the distributions of shell near it's vertex were analyzed numerically, according to several cases of loading. For the sake of more good estimation of plastic dissipating energy, we used the yield-line method from plate theory. The modified criterion of bucking, P super(*) sub(cr), that was suggested in this study, was applied to SUS 302 stain-less steel hemi-spherical shell which had it's Poisson's ratio and Young's modulus with 0.33 and 19700 kg/mm$^2$. From some experiments and comparisons with other results, 재 suggested the critical buckling-load-equation with P super(*) sub(cr)=2E super(*).(t super(2)/a super(2)).{3(1-ν super(*2)} and computed the buckling initiation load with this equation. Because these result from modified criterion have more coincidence than previous one, we prospect this equation can be magnified it's utilities to the other materials.

  • PDF

The Effects of Composite Laminate Layups on Nonlinear Buckling Behavior Using a Degenerated Shell Element (퇴화 쉘 요소를 사용한 적층복합재의 증분형 비선형 좌굴 현상 및 적층 레이업 효과)

  • Cho, Hee-Keun
    • Journal of the Korean Society of Manufacturing Process Engineers
    • /
    • v.15 no.1
    • /
    • pp.50-60
    • /
    • 2016
  • Laminate composites have a number of excellent characteristics in aspects of strength, stiffness, bending, and buckling. Buckling and postbuckling analysis of laminate composites with layups of [90/0]2s, $[{\pm}45/90/0]s$, $[{\pm}45]2s$ has been carried using the Total Lagrangian nonlinear Newton-Raphson method. The formulation of a geometrically nonlinear composite shell element based on a nonlinear large deformation method is presented. The used element is an eight-node degenerated shell element with six degrees of freedom. Square, circular cylinder, and arch panel laminate geometries were analyzed to verify the effects of the layups on the buckling and postbuckling behavior. The results showed that the effects of laminate layups on bucking and postbuckling behavior and the present formulation showed very good agreement with existing references.

Optimal Design of Panel with Trapezoidal Type Stiffeners (사다리꼴 보강재를 활용한 패널의 최적설계)

  • 이종선
    • Transactions of the Korean Society of Machine Tool Engineers
    • /
    • v.12 no.6
    • /
    • pp.71-76
    • /
    • 2003
  • Optimal design of panel with trapezoidal type stiffeners was studied using linear and nonlinear deformation theories. Also analysis method was using closed-form analysis and finite difference energy methods, respectively. Various bucking load factors are obatined for stiffened laminated composite panel with trapezoidal type stiffeners and various aspect ratios, which are made from Carbon/Epoxy USN 125 prepreg and are simply-supported on four edges under uniaxial compression. Optimal design analyses are carried out by the nonlinear search optimizer, ADS.

A Study on the Structural Behavior of Welded Box Columns (강제 교각의 거동에 관한 연구)

  • 김인한;손용석;엄진호;송준엽;권영봉
    • Proceedings of the Computational Structural Engineering Institute Conference
    • /
    • 1999.10a
    • /
    • pp.87-94
    • /
    • 1999
  • The structural behavior of welded steel box columns subjected to axial compression and combined load of axial and horizontal load is described. The nonlinear stress-strain relation of the material and residual stress resulted from welds were included in the analysis. Inelastic buckling analysis of hollow rectangular sections of various width-thickness and slenderness ratios was carried out using the semi-analytical and spline finite strip method to investigate the local and global bucking stress and mode interaction. The buckling stress was compared with test results and design curves. Post-buckling behavior was traced by the finite element program(ADINA) and compared with experimental results. The comparison showed that the ultimate stress can be used for the design purpose.

  • PDF

Inelastic Buckling Analysis of Semi-rigid Frames with Shear Deformations by Haringx's Theories (Haringx의 전단변형 이론을 고려한 부분강절 뼈대구조의 비탄성 좌굴해석)

  • Min, Byoung-Cheol
    • Journal of the Korean Society of Safety
    • /
    • v.29 no.3
    • /
    • pp.64-71
    • /
    • 2014
  • The generalized tangential stiffness matrix of semi-rigid frame element with shear deformations based on Haringx's shear theory is newly derived and compared with the previous study based on Engesser's shear theory. Also, linearized elastic and geometric stiffness matrices are newly presented from the exact tangential stiffness matrix. In oder to obtain the inelastic system buckling load of shear flexible semi-rigid frame structure, the Ef method by tangential modulus theory is adopted and the FE analysis programs are developed. Finally, the shear and semi-rigid effects of system bucking are investigated by two numerical examples.