Ratio Of Buckling Load Research Articles

EFFECTS OF IMPACT VELOCITY AND SLENDERNESS RATIO ON DYNAMIC BUCKLING LOAD FOR LONG COLUMNS

In this research, the buckling behavior of long columns under dynamic load was investigated both experimentally and numerically, and an effective buckling criterion for dynamic load was derived from the results in terms of the impact velocity and the slenderness ratio. In the experiments, a free fall drop-weight type impact testing machine was employed. The dynamic buckling loads were measured by the load sensing block, and the displacements were measured by a high speed magnetic-resistance device. In the numerical analyses, dynamic FEM code 'MSC-Dytran' was used to simulate the typical experimental results, and the validity and the accuracy of the simulations were checked. The dynamic buckling loads at various impact velocities were then systematically investigated. From both experimental and simulated results, it was found that the dynamic to static buckling load ratios can be successfully described as a square function of the slenderness ratio of the columns, while they can be also described by a power law of the applied impact velocity.

Pure global buckling and vibration in laminates with arbitrary shape cut off regions

The pure global buckling and vibration of four sides simply supported as well as clamped anisotropic laminates having an arbitrary shape cut off region that is symmetric with respect to mid-plane have been studied by treating the remaining cut off regions as uniform plates with reduced stiffness. The reduced variation of stiffness of the plate is represented by Fourier series. Computational solutions of the energy principle for the Ritz method in a plate having arbitrary shape of typical cut off regions under biaxial compressive loads are obtained. Some numerical results for the pure global buckling load prediction due to its reduced flexural stiffness for the circular cut off regions and elliptical cut off regions are presented. We find the normalized pure global buckling load ratio decreases as the cut off regions size increases, and the non-dimensional fundamental frequency value decreases as the cut off regions size increases.

Discrete-Field Stability Analysis of X-Braced Lattices

The techniques of discrete-field analysis are used to perform an elastic-stability analysis of a three-dimensional X-braced lattice used as a compression member. Regardless of the number of joints in the system, the solution for the critical buckling load is reduced to solving for the eigenvalues of a 5 × 5 matrix. The formulation thus derived is used to develop a series of curves showing the critical buckling load for various X-braced–lattice configurations and geometries. A comparison of the critical buckling loads for the X-braced lattice indicates that the modified Euler buckling load may vary up to 30% from the loads obtained by the discrete-field–analysis method. The study also shows that as the number of panels increases from four to 32, the buckling-load ratios also increased. The X-braced–lattice depth will affect the buckling load of the lattice system. Variations in chord-member areas create variations in buckling-load ratios. The effects on the buckling ratios of the last two factors tends to diminish as the number of panels increases.

Discrete Field Stability Analysis of Planar Trusses

The techniques of discrete field mechanics are used to perform an elastic stability analysis of planar X-braced columns. Closed-form analytical formulas are derived that are independent of the number of joints in the system; thus, the solution of large, simultaneous equations is avoided. The explicit formula derived is used to develop a series of curves showing the critical-buckling-loads for various planar, x-braced, truss configurations and geometries. A comparison of critical buckling loads for the x-braced truss indicates that the modified Euler critical load may vary up to 85% from the loads obtained by the discrete field analysis method. The study also shows that as the number of panels increases from four to 32, the buckling-load ratios also increase. The x-braced truss depth has a direct relationship to the shearing force, which in turn will affect the buckling load of the truss system. Variations in chord member areas create variations in buckling-load ratios. The effects on the buckling ratios of the last two factors tend to diminish as the number of panels increases.

円筒状海洋構造物の安定性に関する研究 （第２報） 周囲液体からの静液圧と一様なねじり荷重を受ける円筒殻の座屈

This paper deals with the buckling problem of partially liquid-surrounded circular cylindrical shells under torsion to analyze systematically the stability of cylindrical offshore structures. A theoretical analysis is performed by means of the Galerkin method on the basis of the Donnell-type equation for shells, taking the effect of the axisymmetric deformation due to the static liquid pressure into consideration. Calculations are carried out for both simply supported and clamped shells and the torsional buckling loads ks are determined for various values of the shell geometric parameter Z, liquid pressure parameter px and liquid depth ratio l0.The main results obtained are as follows:(1) The torsional buckling load ratio ks decreases monotonously with an increase in the values of l0 and/or px. With an increase in px, the buckling wave number ratio β increases for small value of l0 and decreases for large value of l0.(2) The effects of the shell geometries Z on the torsional buckling load ratio ks are almost negligible for the simply supported shells.(3) The effects of the boundary conditions on the torsional buckling load ratio ks are almost negligible, especially in case of l0=1.0.(4) The effects of the surrounding liquid and the torsional load on the prebuckling and buckling deformation are clarified by means of the contour map representation.