Dynamic Buckling of Cylindrical Shells under Axial Impact in Hamiltonian System

2012 ◽  
Vol 13 (1) ◽  
Author(s):  
Jia-Bin Sun ◽  
Xin-Sheng Xu ◽  
Chee-Wah Lim
Keyword(s):  
Hamiltonian System ◽  
Critical Load ◽  
Impact Load ◽  
Dynamic Buckling ◽  
Inertia Force ◽  
Elastic Cylindrical Shell ◽  
Symplectic Method ◽  
Buckling Mode ◽  
Axial Impact ◽  
Dual Variables

AbstractIn this paper, the dynamic buckling of an elastic cylindrical shell subjected to an axial impact load is analyzed in Hamiltonian system. By employing a symplectic method, the traditional governing equations are transformed into Hamiltonian canonical equations in dual variables. In this system, the critical load and buckling mode are reduced to solving symplectic eigenvalues and eigensolutions respectively. The result shows that the critical load relates with boundary conditions, thickness of the shell and radial inertia force. And the corresponding buckling modes present some local shapes. Besides, the process of dynamic buckling is related to the stress wave, the critical load and buckling mode depend upon the impacted time. This paper gives analytically and numerically some new rules of the buckling problem, which is useful for designing shell structures.

Dynamic Buckling of Cylindrical Shells under Axial Impact in Hamiltonian System

2012 ◽  
Vol 13 (1) ◽  
Author(s):  
Jia-Bin Sun ◽  
Xin-Sheng Xu ◽  
Chee-Wah Lim
Keyword(s):  
Hamiltonian System ◽  
Critical Load ◽  
Impact Load ◽  
Dynamic Buckling ◽  
Inertia Force ◽  
Elastic Cylindrical Shell ◽  
Symplectic Method ◽  
Buckling Mode ◽  
Axial Impact ◽  
Dual Variables

AbstractIn this paper, the dynamic buckling of an elastic cylindrical shell subjected to an axial impact load is analyzed in Hamiltonian system. By employing a symplectic method, the traditional governing equations are transformed into Hamiltonian canonical equations in dual variables. In this system, the critical load and buckling mode are reduced to solving symplectic eigenvalues and eigensolutions respectively. The result shows that the critical load relates with boundary conditions, thickness of the shell and radial inertia force. And the corresponding buckling modes present some local shapes. Besides, the process of dynamic buckling is related to the stress wave, the critical load and buckling mode depend upon the impacted time. This paper gives analytically and numerically some new rules of the buckling problem, which is useful for designing shell structures.

SYMPLECTIC METHOD FOR DYNAMIC BUCKLING OF CYLINDRICAL SHELLS UNDER COMBINED LOADINGS

2013 ◽  
Vol 05 (04) ◽  
pp. 1350042 ◽  
Author(s):  
JIABIN SUN ◽  
XINSHENG XU ◽  
C. W. LIM
Keyword(s):  
Boundary Conditions ◽  
Impact Load ◽  
Cylindrical Shells ◽  
Dynamic Buckling ◽  
Plane Boundary ◽  
Symplectic Method ◽  
Buckling Modes ◽  
Dual Variables ◽  
Combined Action ◽  
Symplectic System

A symplectic system is developed for dynamic buckling of cylindrical shells subjected to the combined action of axial impact load, torsion and pressure. By introducing the dual variables, higher-order stability governing equations are transformed into the lower-order Hamiltonian canonical equations. Critical loads and buckling modes are converted to solving for the symplectic eigenvalues and eigensolutions, respectively. Analytical solutions are presented under various combinations of the in-plane and transverse boundary conditions. The results indicated that in-plane boundary conditions have a significant influence on this problem, especially for the simply supported shells. For the shell with a free impact end, buckling loads should become much lower than others. And the corresponding buckling modes appear as a "bell" shape at the free end. In addition, it is much easier to lose stability for the external pressurized shell. The effect of the shell thickness on buckling results is also discussed in detail.

New insights into the collapsing of cylindrical thin-walled tubes under axial impact load

2007 ◽  
Vol 221 (8) ◽  
pp. 869-885 ◽  
Author(s):  
M Shakeri ◽  
R Mirzaeifar ◽  
S Salehghaffari
Keyword(s):  
Neural Networks ◽  
Impact Load ◽  
Reaction Force ◽  
Plastic Buckling ◽  
Buckling Mode ◽  
Axial Impact ◽  
Geometric Imperfection ◽  
Design Variables ◽  
Initial Geometric Imperfection ◽  
Axisymmetric Plastic

The current paper presents further investigations into the crushing behaviour of circular aluminium tubes subjected to axial impact load. Experiments prove that in order to achieve the real collapsing shape of tubes under axial loads in numerical simulations, an initial geometric imperfection corresponding to the plastic buckling modes should be introduced on the tube geometry before the impact event. In this study, it is shown that the collapsing shape of tube is affected by this initial imperfection and consequently it is shown that by applying an initial geometric imperfection similar to the axisymmetric plastic buckling mode, the tubes tend to collapse in a concertina mode. This phenomenon is studied for circular tubes subjected to axial impact load and two design methods are suggested to activate the axisymmetric plastic buckling mode, using an initial circumferential edge groove and using one- and two-rigid rings on the tube. In each case the broadening of the concertina collapsing region is estimated using numerical simulations. Experimental tests are performed to study the influence of cutting the edge groove on the collapsing mode. In order to optimize the crashworthiness parameters of the structure such as the absorbed energy, maximum deflection in axial direction, maximum reaction force, and mean reaction force, a system of neural networks is designed to reproduce the crushing behaviour of the structure, which is often non-smooth and highly non-linear in terms of the design variables (diameter, thickness, and length of tube). The finite-element code ABAQUS/Explicit is used to generate the training and test sets for the neural networks. The response surface of each objective function (crashworthiness parameters) against the change of design variables is calculated and both single-objective and multi-objective optimizations are carried out using the genetic algorithm.

Computer Simulation on the Dynamic Buckling of Initial-Defect Plates under Axial Step Load

2015 ◽  
Vol 1094 ◽  
pp. 482-486
Author(s):  
Yu Peng Zong ◽  
Zhi Jun Han ◽  
Guo Yun Lu
Keyword(s):  
Computer Simulation ◽  
Boundary Conditions ◽  
Impact Load ◽  
Time History ◽  
Lower Surface ◽  
Dynamic Buckling ◽  
Axial Impact ◽  
Different Boundary Conditions ◽  
Initial Defect ◽  
Symmetric Point

Computer simulation on the dynamic buckling of different forms of initial-defect and different boundary conditions plates under axial impact load was carried out by using ABAQUS /Standard.The strain-time history curve of the symmetric point of upper and lower surface is give,they are coincidence before the buckling and suddenly separate when the buckling occur which is called be bifurcation,and the critical buckling time is also acquired. The results indicate that the influence of different initial-defect locations and amplitudes on the dynamic buckling is very great.

Dynamic Buckling of Externally Pressurized Imperfect Cylindrical Shells

1975 ◽  
Vol 42 (2) ◽  
pp. 316-320 ◽  
Author(s):  
D. Lockhart ◽  
J. C. Amazigo
Keyword(s):  
Asymptotic Expression ◽  
Cylindrical Shells ◽  
Simple Relation ◽  
Dynamic Buckling ◽  
Fourier Component ◽  
Buckling Load ◽  
Buckling Mode ◽  
Geometric Imperfections ◽  
Circular Cylindrical Shells ◽  
Step Loading

The dynamic buckling of imperfect finite circular cylindrical shells subjected to suddenly applied and subsequently maintained lateral or hydrostatic pressure is studied using a perturbation method. The geometric imperfections are assumed small but arbitrary. A simple asymptotic expression is obtained for the dynamic buckling load in terms of the amplitude of the Fourier component of the imperfection in the shape of the classical buckling mode. Consequently, for small imperfection, there is a simple relation between the dynamic buckling load under step-loading and the static buckling load. This relation is independent of the shape of the imperfection.

The nonlinear dynamic buckling behaviour of imperfect solar cells subjected to impact load

2021 ◽  
Vol 169 ◽  
pp. 108317
Author(s):  
Qingya Li ◽  
Yuhang Tian ◽  
Di Wu ◽  
Wei Gao ◽  
Yuguo Yu ◽  
...  
Keyword(s):  
Solar Cells ◽  
Nonlinear Dynamic ◽  
Impact Load ◽  
Dynamic Buckling

Analysis of Elasticity Solution of Bi-Direction Functionally Graded Piezoelectric Beam Subject to Voltage

2012 ◽  
Vol 166-169 ◽  
pp. 824-827 ◽  
Author(s):  
Y Z Yang
Keyword(s):  
Hamiltonian System ◽  
Exact Solutions ◽  
Material Properties ◽  
Functionally Graded ◽  
Symplectic Method ◽  
Elasticity Solution ◽  
Numerical Examples ◽  
Piezoelectric Beam ◽  
Functionally Graded Piezoelectric

This paper presents symplectic method for the derivation of exact solutions of functionally graded piezoelectric beam with the material properties varying exponentially both along the axial and transverse coordinates. In the approach, the related equations and formulas are developed in terms of dual equations, which can be solved by variables separation and symplectic expansion in Hamiltonian system. To verify advantages of the method, numerical examples of bi-directional functionally piezoelectric beam are discussed.

scholarly journals DYNAMIC BEHAVIOR OF REINFORCED CONCRETE COLUMN UNDER ACCIDENTAL IMPACT

2021 ◽  
Vol 17 (3) ◽  
pp. 120-131
Author(s):  
Sergey Savin ◽  
Vitaly Kolchunov
Keyword(s):  
Reinforced Concrete ◽  
Analytical Solution ◽  
High Speed ◽  
Impact Load ◽  
Dynamic Buckling ◽  
Shock Load ◽  
Dynamic Factor ◽  
Physical Parameters ◽  
Concrete Column ◽  
Reinforced Concrete Column

The analysis of scientific literature shows that to date, the physical parameters of the deformation of reinforced concrete bar structures during their dynamic buckling and the influence of the dissipative properties of the structural system on this process remain insufficiently studied. In this regard, the paper proposes an analytical solution to the problem of dynamic buckling of a reinforced concrete column when it is loaded with an impact load, taking into account the presence of initial geometric and (or) physical imperfections and damping properties of the system, as well as an analysis and assessment of the column deformationparameters based on the obtained analytical solution. An expression for the dynamic deflection of a bar element under its axial loading with a high-speed shock load, taking into account damping, is obtained in an analytical form. For practical calculations in a quasi-static formulation, the paper proposes an expression for the dynamic factor kd of bar structures under axial shock load. A numerical example of calculating a reinforced concrete column using the obtained analytical expressions with and without damping is considered. It was found that the maximum deflection of the elastic axis of the column under high-speed loading was achieved at t = 0.04 s. In this case, the total dynamic deflection taking into account damping was 4.8% less than the deviation without taking into account damping and 1.18 times more than the corresponding static value.

scholarly journals Experimental Study on Axial Impact Mitigating Stick-Slip Vibration with a PDC Bit

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Yong Wang ◽  
Hongjian Ni ◽  
Yiliu (Paul) Tu ◽  
Ruihe Wang ◽  
Xueying Wang ◽  
...  
Keyword(s):  
Impact Force ◽  
Impact Load ◽  
Similarity Theory ◽  
Impact Frequency ◽  
Stick Slip ◽  
Axial Impact ◽  
Pdc Bit ◽  
Fluctuation Amplitude ◽  
Rotary Speed ◽  
The Impact

Stick-slip vibration reduces the drilling rate of penetration, causes early wear of bits, and threatens the safety of downhole tools. Therefore, it is necessary to study suppression methods of stick-slip vibration to achieve efficient and safe drilling. Field tests show that the use of downhole axial impactors is helpful to mitigate stick-slip vibration and improve rock-breaking efficiency. However, there are many deficiencies in the study of how axial impact load affects stick-slip vibration of a PDC bit. In this paper, based on the two-degrees-of-freedom spring-mass-damper model and similarity theory, a laboratory experiment device for suppressing stick-slip vibration of a PDC bit under axial impact load has been developed, and systematic experimental research has been carried out. The results show that the axial impact force can suppress the stick-slip vibration by reducing the amplitude of weight on bit and torque fluctuations and by increasing the main frequency of torque. The amplitude of impact force affects the choice of the optimal back-rake angle. The impact frequency is negatively correlated with the fluctuation amplitude of the rotary speed. When the impact frequency is greater than 100 Hz, the fluctuation amplitude of the rotary speed will not decrease.

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