Effects of Solid Viscosities, Loading Velocities and Initial Deflections to Dynamic Buckling Loads of a Column

1969 ◽  
Vol 73 (706) ◽  
pp. 890-894
Author(s):  
Shin-Ichi Suzuki
Keyword(s):  
Dynamic Load ◽  
Analytical Methods ◽  
Dynamic Buckling ◽  
Static Loads ◽  
Buckling Loads ◽  
Load Factors

It is a well-known fact that buckling values for columns under dynamical loads are different from those under static loads. Meier, Gerard and Davidson have already investigated the dynamics of the buckling of elastic columns theoretically and experimentally, and Hoff discussed analytical methods in detail. However, solid viscosities are neglected in all these researches. Previously, the author obtained the relationships between dynamic load factors and solid viscosities, and it was found that their effects on dynamic load factors cannot be neglected. It will be interesting to investigate the relationships between solid viscosities and dynamic buckling values.

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

2008 ◽  
Vol 22 (31n32) ◽  
pp. 5596-5602 ◽  
Author(s):  
K. MIMURA ◽  
T. UMEDA ◽  
M. YU ◽  
Y. UCHIDA ◽  
H. YAKA
Keyword(s):  
Impact Velocity ◽  
Dynamic Load ◽  
Slenderness Ratio ◽  
Testing Machine ◽  
Dynamic Buckling ◽  
Impact Testing ◽  
Buckling Load ◽  
Square Function ◽  
Buckling Loads ◽  
The Impact

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.

The Specific Characteristics of Shock and Blast Impacts on Construction Sites

2021 ◽  
pp. 81-88
Author(s):  
A.A. Komarov ◽  
Keyword(s):  
Dynamic Load ◽  
Static Load ◽  
Dynamic Loads ◽  
Potential Hazard ◽  
Construction Sites ◽  
Static Loads ◽  
Equivalent Static Loads ◽  
Plane Crash ◽  
Nuclear Plants ◽  
The Impact

The practices of hazardous and unique facilities’ construction imply that specific attention is paid to the issues of safety. Threats associated with crash impacts caused by moving cars or planes are considered. To ensure safety of these construction sites it is required to know the potential dynamic loads and their destructive capacity. This article considers the methodology of reducing dynamic loads associated with impacts caused by moving collapsing solids and blast loads to equivalent static loads. It is demonstrated that practically used methods of reduction of dynamic loads to static loads are based in schematization only of the positive phase of a dynamic load in a triangle forms are not always correct and true. The historical roots of this approach which is not correct nowadays are shown; such approach considered a detonation explosion as a source of dynamic load, including TNT and even a nuclear weapon. Application of the existing practices of reduction of dynamic load to static load for accidental explosions in the atmosphere that occur in deflagration mode with a significant vacuumization phase may cause crucial distortion of predicted loads for the construction sites. This circumstance may become a matter of specific importance at calculations of potential hazard of impacts and explosions in unique units — for instance, in the nuclear plants. The article considers a situation with a plane crash, the building structure load parameters generated at the impact caused by a plane impact and the following deflagration explosion of fuel vapors are determined.

Parametric Instability of Tapered Beams by Finite Element Method

1982 ◽  
Vol 24 (4) ◽  
pp. 205-208 ◽  
Author(s):  
P. K. Datta ◽  
S. Chakraborty
Keyword(s):  
Finite Element ◽  
Dynamic Load ◽  
Parametric Instability ◽  
Mathieu Equation ◽  
Stability Diagram ◽  
Load Factor ◽  
Element Analysis ◽  
Load Factors ◽  
Principal Region ◽  
Dynamic Load Factor

The dynamic stability behaviour of a tapered beam has been studied using a finite element analysis. The instability zones of the parametric stability diagram have been discussed for the entire ranges of static and dynamic load factors. It has been observed that at high values of static load and beyond a particular value of the dynamic load factor, the periodic solution of the Mathieu equation does not exist in the principal region. This leads to unstable behaviour due to large displacement of the beam due to increasing values of static and dynamic load factors.

DYNAMIC BUCKLING AND POSTBUCKLING OF A COMPOSITE SHELL

2010 ◽  
Vol 10 (04) ◽  
pp. 791-805 ◽  
Author(s):  
CHRISTOS C. CHAMIS
Keyword(s):  
Solution Method ◽  
Composite Shell ◽  
Dynamic Buckling ◽  
Dynamic Loads ◽  
Composite Cylindrical Shell ◽  
Buckling Loads ◽  
Loading Rates ◽  
Computer Codes ◽  
Updated Lagrangian ◽  
Composite Mechanics

A computationally effective method for evaluating the dynamic buckling and postbuckling of thin composite shells is described. It is a judicious combination of available computer codes for finite element, composite mechanics and incremental structural analysis. The solution method is an incrementally updated Lagrangian. It is illustrated by applying it to a thin composite cylindrical shell subjected to dynamic loads. Buckling loads are evaluated to demonstrate the effectiveness of the method. A universal plot is obtained for the specific shell that can be used to approximate buckling loads for different dynamic loading rates. Results from this plot show that the faster the rate, the higher the buckling load and the shorter the time. They also show that the updated solution can be carried out in the postbuckling regime until the shell collapses completely. Comparisons with published literature indicate reasonable agreement.

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