• Title, Summary, Keyword: Critical buckling temperature

Search Result 69, Processing Time 0.044 seconds

Parametric Study of Thermal Stability on Continuous Welded Rail

  • Choi, Dong-Ho;Na, Ho-Sung
    • International Journal of Railway
    • /
    • v.3 no.4
    • /
    • pp.126-133
    • /
    • 2010
  • The thermal buckling analysis of curved continuous welded rail (CWR) is studied for the lateral buckling prevention. This study includes a thermal buckling theory which accounts for both thermal and vehicle loading effects in the evaluation of track stability. The parameters include rail size, track lateral resistance, track longitudinal and torsional stiffnesses, initial misalignment amplitude and wavelength, track curvature, tie-ballast friction coefficient and truck center spacing. Parametric studies are performed to evaluate the effects of the individual parameters on the upper and lower critical buckling temperatures. The results show that the upper critical buckling temperature is highly affected by the uplift due to vehicle loads. This study provides a guideline for the improvement of stability for dynamic buckling in curved CWR track.

  • PDF

Post-buckling behaviours of axially restrained steel columns in fire

  • Li, Guo-Qiang;Wang, Peijun;Hou, Hetao
    • Steel and Composite Structures
    • /
    • v.9 no.2
    • /
    • pp.89-101
    • /
    • 2009
  • This paper presents a simplified model to study post-buckling behaviours of the axially restrained steel column at elevated temperatures in fire. The contribution of axial deformation to the curvature of column section is included in theoretical equations. The possible unloading at the convex side of the column when buckling occurs is considered in the stress-strain relationship of steel at elevated temperatures. Parameters that affect structural behaviours of the axial restrained column in fire are studied. The axial restraint cause an increase in the axial force before the column buckles; the buckling temperature of restrained columns will be lower than non-restrained steel columns. However, the axial force of a restrained column decreases after the column buckles with the elevation of temperatures, so make use of the post-buckling behaviour can increase the critical temperature of restrained columns. Columns with temperature gradient across the section will produce lower axial force at elevated temperatures.

Thermal post-buckling analysis of a laminated composite beam

  • Akbas, Seref D.
    • Structural Engineering and Mechanics
    • /
    • v.67 no.4
    • /
    • pp.337-346
    • /
    • 2018
  • The purpose of this study is to investigate thermal post-buckling analysis of a laminated composite beam subjected under uniform temperature rising with temperature dependent physical properties. The beam is pinned at both ends and immovable ends. Under temperature rising, thermal buckling and post-buckling phenomena occurs with immovable ends of the beam. In the nonlinear kinematic model of the post-buckling problem, total Lagrangian approach is used in conjunction with the Timoshenko beam theory. Also, material properties of the laminated composite beam are temperature dependent: that is the coefficients of the governing equations are not constant. In the solution of the nonlinear problem, incremental displacement-based finite element method is used with Newton-Raphson iteration method. The effects of the fibber orientation angles, the stacking sequence of laminates and temperature rising on the post-buckling deflections, configurations and critical buckling temperatures of the composite laminated beam are illustrated and discussed in the numerical results. Also, the differences between temperature dependent and independent physical properties are investigated for post-buckling responses of laminated composite beams.

Thermal buckling analysis of SWBNNT on Winkler foundation by non local FSDT

  • Semmah, Abdelwahed;Heireche, Houari;Bousahla, Abdelmoumen Anis;Tounsi, Abdelouahed
    • Advances in nano research
    • /
    • v.7 no.2
    • /
    • pp.89-98
    • /
    • 2019
  • In this work, the thermal buckling characteristics of zigzag single-walled boron nitride (SWBNNT) embedded in a one-parameter elastic medium modeled as Winkler-type foundation are investigated using a nonlocal first-order shear deformation theory (NFSDT). This model can take into account the small scale effect as well as the transverse shear deformation effects of nanotubes. A closed-form solution for nondimensional critical buckling temperature is obtained in this investigation. Further the effect of nonlocal parameter, Winkler elastic foundation modulus, the ratio of the length to the diameter, the transverse shear deformation and rotary inertia on the critical buckling temperature are being investigated and discussed. The results presented in this paper can provide useful guidance for the study and design of the next generation of nanodevices that make use of the thermal buckling properties of boron nitride nanotubes.

Local Buckling Analysis of Steel Beams at Elevated Temperature (온도상승에 따른 Steel-beam의 국부좌굴해석)

  • Jang, Myung-Woong;Kang, Moon-Myung;Kang, Sung-Duk
    • Journal of Korean Association for Spatial Structures
    • /
    • v.3 no.1
    • /
    • pp.69-75
    • /
    • 2003
  • This paper is represented a general equations to obtain the elastic local buckling stresses for the flange and web of H-beam under compression at elevated temperatures and is also developed the software to perform the elastic local buckling analysis at elevated temperatures. Eurocode3 Part 1.2 are used to analyse the decrease in steel yield strength and elastic modulus at elevated temperatures. For design examples of 6 H-beams, the elastic local buckling stresses and critical temperatures for the slenderness ratio $(b/t_f\;and\;d/t_w)$ of the flange and web under uniform compression at elevated temperatures have been analysed by a computer program of this paper. It can be seen that the computer analytical results of this study show a good agreement with the experimental results by Wadee.

  • PDF

Thermal Buckling of Thick Laminated Composite Plates under Uniform Temperature Distribution (균일분포 온도하의 두꺼운 복합 재료 적층판의 열적 좌굴 해석)

  • Lee, Young-Shin;Lee, Yeol-Wha;Yang, Myung-Seog;Park, Bock-Sun;Lee, Jong-Soo
    • Transactions of the Korean Society of Mechanical Engineers
    • /
    • v.17 no.7
    • /
    • pp.1686-1699
    • /
    • 1993
  • In this paper, the thermal buckling of thick composite angle-ply laminates subject to uniform temperature distribution is studied. For the plates of 4-edges simply supported condition and those of 4-edges clamped condition, the critical buckling temperatue is derived, using tile finite element method based on the shear deformation theory. The effects of lamination angle, layer number, laminate thickness, plate aspect ratio and boundary constraints upon the critical buckling temperature are presented.

Thermal buckling analysis of shear deformable laminated orthotropic plates by differential quadrature

  • Moradi, S.;Mansouri, Mohammad Hassan
    • Steel and Composite Structures
    • /
    • v.12 no.2
    • /
    • pp.129-147
    • /
    • 2012
  • In this paper, the thermal buckling analysis of rectangular composite laminated plates is investigated using the Differential Quadrature (DQ) method. The composite plate is subjected to a uniform temperature distribution and arbitrary boundary conditions. The analysis takes place in two stages. First, pre-buckling forces due to a temperature rise are determined by using a membrane solution. In the second stage, the critical temperature is predicted based on the first-order shear deformation theory. To verify the accuracy of the method, several case studies were used and the numerical results were compared with those of other published literatures. Moreover, the effects of several parameters such as aspect ratio, fiber orientation, modulus ratio, and various boundary conditions on the critical temperature were examined. The results confirm the efficiency and accuracy of the DQ method in dealing with this class of engineering problems.

A study on the Thermal Buckling and Postbuckling of a Laminated Composite Beam with Embedded SMA Actuators (형상기억합금 선을 삽입한 복합적층 보의 열좌굴 및 좌굴후 거동에 관한 연구)

  • Choi, S.;Lee, J.J.;Lee, D.C.
    • Composites Research
    • /
    • v.12 no.3
    • /
    • pp.55-65
    • /
    • 1999
  • In this paper, the thermal buckling and postbuckling behaviour of composite beam with embedded shape memory alloy (SMA) wires are investigated experimentally and analytically. The results of thermal buckling tests on uniformly heated, clamped, composite beam embedded with SMA wire actuators are presented and discussed in consideration of geometric imperfections, slenderness ratio of beam and embedding position of SMA wire actuators. The shape recovery force can reduce the thermal expansion of composite laminated beam, which result in increment of the critical buckling temperature and reduction of the lateral deflection of postbuckling behaviours. It is presented quantitatively on the temperature-load-deflection behaviour records how the shape recovery force affects the thermal buckling. The cross tangential method is suggested to calculate the critical buckling temperature on the temperature-deflection plot. Based on the experimental analysis, the new formula is also proposed to describe the critical buckling temperature of a laminated composite beam with embedded SMA wire actuators.

  • PDF

Post-buckling analysis of Timoshenko beams with temperature-dependent physical properties under uniform thermal loading

  • Akbas, Seref Doguscan;Kocaturk, Turgut
    • Structural Engineering and Mechanics
    • /
    • v.44 no.1
    • /
    • pp.109-125
    • /
    • 2012
  • Post-buckling behavior of Timoshenko beams subjected to uniform temperature rising with temperature dependent physical properties are studied in this paper by using the total Lagrangian Timoshenko beam element approximation. The beam is clamped at both ends. In the case of beams with immovable ends, temperature rise causes compressible forces end therefore buckling and post-buckling phenomena occurs. It is known that post-buckling problems are geometrically nonlinear problems. Also, the material properties (Young's modulus, coefficient of thermal expansion, yield stress) are temperature dependent: That is the coefficients of the governing equations are not constant in this study. This situation suggests the physical nonlinearity of the problem. Hence, the considered problem is both geometrically and physically nonlinear. The considered highly non-linear problem is solved considering full geometric non-linearity by using incremental displacement-based finite element method in conjunction with Newton-Raphson iteration method. The beams considered in numerical examples are made of Austenitic Stainless Steel (316). The convergence studies are made. In this study, the difference between temperature dependent and independent physical properties are investigated in detail in post-buckling case. The relationships between deflections, thermal post-buckling configuration, critical buckling temperature, maximum stresses of the beams and temperature rising are illustrated in detail in post-buckling case.

Buckling and dynamic characteristics of a laminated cylindrical panel under non-uniform thermal load

  • Bhagat, Vinod S.;Pitchaimani, Jeyaraj;Murigendrappa, S.M.
    • Steel and Composite Structures
    • /
    • v.22 no.6
    • /
    • pp.1359-1389
    • /
    • 2016
  • Buckling and free vibration behavior of a laminated cylindrical panel exposed to non-uniform thermal load is addressed in the present study. The approach comprises of three portions, in the first portion, heat transfer analysis is carried out to compute the non-uniform temperature fields, whereas second portion consists of static analysis wherein stress fields due to thermal load is obtained, and the last portion consists of buckling and prestressed modal analyzes to capture the critical buckling temperature as well as first five natural frequencies and associated mode shapes. Finite element is used to perform the numerical investigation. The detailed parametric study is carried out to analyze the effect of nature of temperature variation across the panel, laminate sequence and structural boundary constraints on the buckling and free vibration behavior. The relation between the buckling temperature of the panel under uniform temperature field and non-uniform temperature field is established using magnification factor. Among four cases considered in this study for position of heat sources, highest magnification factor is observed at the forefront curved edge of the panel where heat source is placed. It is also observed that thermal buckling strength and buckling mode shapes are highly sensitive to nature of temperature field and the effect is significant for the above-mentioned temperature field. Furthermore, it is also observed that the panel with antisymmetric laminate has better buckling strength. Free vibration frequencies and the associated mode shapes are significantly influenced by the non-uniform temperature variations.