Influence of Loading on Mode Localization in Periodic Structures

1995 ◽  
Vol 48 (11S) ◽  
pp. S132-S137 ◽  
Author(s):  
Reyolando M. L. R. F. Brasil ◽  
Carlos E. N. Mazzilli
Keyword(s):  
Small Parameter ◽  
Periodic Structures ◽  
Computer Code ◽  
Vibration Modes ◽  
Finite Element Program ◽  
Mode Localization ◽  
Element Program ◽  
The Masses ◽  
Lumped Masses ◽  
Two Degree Of Freedom

This paper addresses the problem of the presence of a slightly disordered loading in otherwise ordered periodic structures as an element to trigger the phenomenon of vibration mode localization due to its effect in their stiffness. The sample structures are basically cantilever columns supporting the loads due to large lumped masses in their top which may vary according to a disorder related small parameter. They are connected by very flexible springs. A first series of results deals with a two-degree-of-freedom model where localization is achieved due to loading disorder. The frequencies and displacements show very sharp and nonlinear variation when the small parameter changes slightly around its zero value. The results for this simple model compare well with those of a finite element program developed by the authors. For a more complex example, another model of a rank of six columns is analyzed by the same computer code. A pseudo-random variation of the masses is considered and the resulting vibration modes are compared to those of the ordered structure, which are global in nature and present a sinusoidal spatial distribution. Again, due to mode localization, motions in the perturbed structure are found to be restricted largely to one of the masses.

Dynamic Analysis of Large Steel Structure Truss System

2011 ◽  
Vol 101-102 ◽  
pp. 387-391
Author(s):  
Chu Qun Wu ◽  
Fan Wang ◽  
Shao Yong Wang
Keyword(s):  
Dynamic Analysis ◽  
Vibration Mode ◽  
Steel Structure ◽  
Vibration Modes ◽  
Finite Element Program ◽  
Large Steel ◽  
Dynamic Computation ◽  
Modes Of Vibration ◽  
Element Program ◽  
Earthquake Vibration

The deformation of the large steel structure truss system, which was subjected to constant loads, variable loads and wind loads, was calculated by using the 3D3S steel structure analysis program. The periods and the vibration mode from the first to the ninth order of the structure were obtained by the earthquake vibration mode period analysis. The dynamic computation of the structure showed that the period difference of the vibration modes is small. The frequencies and the modes of vibration from the first to the ninth order of the same structure mode were calculated by using the ANSYS finite element program. The frequencies and the modes of vibration from the first to the ninth order of the building were obtained by the dynamic analysis of the structure. The dynamic computation of the structure shows that the frequencies difference of the vibration modes is small. The vibration instability is possible for the structure.

Computation of the Eigenvalues of Wave Propagation in Periodic Substructural Systems

1993 ◽  
Vol 115 (4) ◽  
pp. 422-426 ◽  
Author(s):  
F. W. Williams ◽  
Zhong Wanxie ◽  
P. N. Bennett
Keyword(s):  
Wave Propagation ◽  
Timoshenko Beam ◽  
Natural Vibration ◽  
Natural Frequencies ◽  
Periodic Structures ◽  
Dynamic Stiffness ◽  
Finite Element Program ◽  
Element Program ◽  
Simple Supports ◽  
Phase Propagation

The wave propagation constants of periodic structures are computed using the exact dynamic stiffness matrix of a typical substructure. The approach used is to show that wave propagation and the natural vibration eigenproblem are similar to such an extent that methods used to find the natural frequencies of a structure can be applied to find its wave propagation constants. The Wittrick-Williams algorithm has been incorporated into a finite element program, JIGFEX, in conjunction with exact dynamic member stiffnesses, to ensure that no phase propagation eigenvalues are missed during computation. The accuracy of the present approach is then demonstrated by comparing the results that it gives to analytically determined wave propagation curves for a Timoshenko beam on periodic simple supports. Finally, phase propagation curves are given for a complex Timoshenko beam structure of a type that would be very difficult to analyze analytically.

Anderson Localization Phenomenon in Periodic Structures

2013 ◽  
Author(s):  
Reyolando M. Brasil
Keyword(s):  
Anderson Localization ◽  
Periodic Structures ◽  
Small Variation ◽  
Slight Variation ◽  
Vibration Modes ◽  
Axial Loads ◽  
Mode Localization ◽  
Localization Phenomenon ◽  
Stiffness Matrices ◽  
Light Coupling

We study the occurrence in structures of a phenomenon similar to Anderson localization. This the vibration modes localization in structures composed of several nominally identical lightly coupled modular substructures. In an ideal perfect model, the vibration modes are global in nature, spreading to the whole structure. In real structures there are no two completely identical segments. Constructive or loading imperfections generate slight variation of the dynamic characteristics of each module. As the level of disorder grows and coupling between modules becomes lighter, the resulting vibration modes change considerably. Vibration energy may become confined to a few segments. This is the Mode Localization Phenomenon. We present models of long modular planar trussed structures. Light coupling is considered between the initially identical modules. A certain degree of imperfection is introduced by adopting a slight variation in the loading of the modules. This will generate a small variation in the global stiffness of the system as the axial loads in the bars affect their Geometric Stiffness Matrices.

Water Hammer Response of Flexible Piping by Component Synthesis

1991 ◽  
Vol 113 (1) ◽  
pp. 115-119 ◽  
Author(s):  
F. J. Hatfield ◽  
D. C. Wiggert
Keyword(s):  
Finite Element ◽  
Dynamic Pressure ◽  
Equations Of Motion ◽  
Computer Code ◽  
Water Hammer ◽  
Mode Shapes ◽  
Finite Element Program ◽  
Coupled Equations ◽  
Alternative Approach ◽  
Element Program

Water hammer pressure in piping is modified by the consequent motion of the piping. In general, accurate estimates of dynamic pressure and pipe displacement must account for this interaction. One approach is to formulate and solve the coupled equations of motion for the liquid and pipe structure. Implementation for practical pipe systems would require a computer code comparable in scope to a structural finite element program combined with a hydrodynamics program. This paper presents an alternative approach that utilizes any available finite element program to compute natural frequencies and mode shapes of the piping, and then uses those modes to modify a hydrodynamic analysis and to predict motion of the piping. An example analysis demonstrates application of the method to assess the consequence of removing a brace intended to restrain pipe motion caused by water hammer. Results are compared to those given by analyses that neglect the effect of pipe motion on pressure.

Friction Force and Stresses Analysis for Contact of Assembled Details

2006 ◽  
Vol 113 ◽  
pp. 334-338
Author(s):  
Z. Dreija ◽  
O. Liniņš ◽  
Fr. Sudnieks ◽  
N. Mozga
Keyword(s):  
Mechanical Properties ◽  
Surface Roughness ◽  
Plastic Deformation ◽  
Friction Force ◽  
Sliding Friction ◽  
Friction Model ◽  
Contact Interface ◽  
Finite Element Program ◽  
Elastic Plastic ◽  
Element Program

The present work deals with the computation of surface stresses and deformation in the presence of friction. The evaluation of the elastic-plastic contact is analyzed revealing three distinct stages that range from fully elastic through elastic-plastic to fully plastic contact interface. Several factors of sliding friction model are discussed: surface roughness, mechanical properties and contact load and areas that have strong effect on the friction force. The critical interference that marks the transition from elastic to elastic- plastic and plastic deformation is found out and its connection with plasticity index. A finite element program for determination contact analysis of the assembled details and due to details of deformation that arose a normal and tangencial stress is used.

scholarly journals The impact of drilling and slitting construction on damage field: evolution characteristics in low-permeability coal seam

2021 ◽  
Vol 37 ◽  
pp. 205-215
Author(s):  
Heng Chen ◽  
Hongmei Cheng ◽  
Aibin Xu ◽  
Yi Xue ◽  
Weihong Peng
Keyword(s):  
Finite Element ◽  
Rock Mass ◽  
Damage Mechanics ◽  
Effective Strain ◽  
Secondary Development ◽  
Distribution Area ◽  
Finite Element Program ◽  
Element Program ◽  
Mining Face ◽  
The Impact

ABSTRACT The fracture field of coal and rock mass is the main channel for gas migration and accumulation. Exploring the evolution law of fracture field of coal and rock mass under the condition of drilling and slitting construction has important theoretical significance for guiding efficient gas drainage. The generation and evolution process of coal and rock fissures is also the development and accumulation process of its damage. Therefore, based on damage mechanics and finite element theory, the mathematical model is established. The damage variable of coal mass is defined by effective strain, the elastoplastic damage constitutive equation is established and the secondary development of finite element program is completed by FORTRAN language. Using this program, the numerical simulation of drilling and slitting construction of the 15-14120 mining face of Pingdingshan No. 8 Mine is carried out, and the effects of different single borehole diameters, different kerf widths and different kerf heights on the distribution area of surrounding coal fracture field and the degree of damage are studied quantitatively. These provide a theoretical basis for the reasonable determination of the slitting and drilling arrangement parameters at the engineering site.

Mechanical Property Analysis and Numerical Simulation of Honeycomb Sandwich Structure’s Core

2013 ◽  
Vol 631-632 ◽  
pp. 518-523 ◽  
Author(s):  
Xiang Li ◽  
Min You
Keyword(s):  
Numerical Simulation ◽  
Elastic Constants ◽  
Sandwich Structure ◽  
Optimization Design ◽  
Simulation Analysis ◽  
Finite Element Program ◽  
Honeycomb Sandwich ◽  
Calculation Results ◽  
Element Program ◽  
Typical Satellite

Owing to the lack of a good theory method to obtain the accurate equivalent elastic constants of hexagon honeycomb sandwich structure’s core, the paper analyzed mechanics performance of honeycomb sandwich structure’s core and deduced equivalent elastic constants of hexagon honeycomb sandwich structure’s core considering the wall plate expansion deformation’s effect of hexagonal cell. And also a typical satellite sandwich structure was chose as an application to analyze. The commercial finite element program ANSYS was employed to evaluate the mechanics property of hexagon honeycomb core. Numerical simulation analysis and theoretical calculation results show the formulas of equivalent elastic constants is correct and also research results of the paper provide theory basis for satellite cellular sandwich structure optimization design.

Finite Element Analysis on the Deformation of Energy-Saving Wire-Mesh Frame Wallboard

2014 ◽  
Vol 501-504 ◽  
pp. 731-735
Author(s):  
Li Zhang ◽  
Kang Li
Keyword(s):  
Finite Element ◽  
Energy Saving ◽  
Theoretical Basis ◽  
Steel Wire ◽  
Wire Mesh ◽  
Design Parameters ◽  
Element Analysis ◽  
Finite Element Program ◽  
Element Program ◽  
Influence Degree

This paper analyzes the influence degree of related design parameters of wire-mesh frame wallboard on deformation through finite element program, providing theoretical basis for the design and test of steel wire rack energy-saving wallboard.

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