Stability and Dynamic Analyses of Transmission Tower-Line Systems Subjected to Conductor Breaking

2017 ◽  
Vol 17 (06) ◽  
pp. 1771013 ◽  
Author(s):  
Jia-Xiang Li ◽  
Hong-Nan Li ◽  
Xing Fu
Keyword(s):  
Stability Analysis ◽  
Failure Modes ◽  
Dynamic Instability ◽  
Progressive Collapse ◽  
Static Stability ◽  
Transmission Tower ◽  
Initial Tension ◽  
Line System ◽  
Ice Loads ◽  
The Stability

Ice loads exerted on the transmission line can increase the probability of conductor breaking, which will lead to the stability failure of transmission towers. In this paper, a transmission tower-line system is established for two towers and three span lines. Then the nonlinear static stability analysis and nonlinear dynamic stability analysis induced by the conductor breaking are carried out to obtain the load versus displacement curves, while studying the failure modes of the transmission tower-line system. Moreover, the ice load and initial eccentricity are considered in the numerical simulation. In addition, a parametric analysis is performed to investigate the influence of span, insulator length and initial tension force on the stability failure of the system. The results show that the dynamic instability will occur earlier than the static instability due to the dynamic impact effect and conductor breaking with ice loads can lead to the progressive collapse of the transmission tower-line system. Finally, the span length has the greatest effect on the response of transmission tower caused by conductor breaking.

Instability of Heated Panels in Supersonic Air Flow

2008 ◽  
Vol 33-37 ◽  
pp. 1101-1108
Author(s):  
Zhi Chun Yang ◽  
Wei Xia
Keyword(s):  
Stability Analysis ◽  
Stability Boundary ◽  
Boundary Curve ◽  
Static Stability ◽  
Static Deformation ◽  
Limit Cycle Oscillation ◽  
Aerodynamic Load ◽  
Aeroelastic System ◽  
Aerodynamic Pressure ◽  
The Stability

An investigation on the stability of heated panels in supersonic airflow is performed. The nonlinear aeroelastic model for a two-dimensional panel is established using Galerkin method and the thermal effect on the panel stiffness is also considered. The quasi-steady piston theory is employed to calculate the aerodynamic load on the panel. The static and dynamic stabilities for flat panels are studied using Lyapunov indirect method and the stability boundary curve is obtained. The static deformation of a post-buckled panel is then calculated and the local stability of the post-buckling equilibrium is analyzed. The limit cycle oscillation of the post-buckled panel is simulated in time domain. The results show that a two-mode model is suitable for panel static stability analysis and static deformation calculation; but more than four modes are required for dynamic stability analysis. The effects of temperature elevation and dimensionless parameters related to panel length/thickness ratio, material density and Mach number on the stability of heated panel are studied. It is found that panel flutter may occur at relatively low aerodynamic pressure when several stable equilibria exist for the aeroelastic system of heated panel.

scholarly journals Collapse Analysis of a Transmission Tower-Line System Induced by Ice Shedding

2021 ◽  
Vol 9 ◽  
Author(s):  
Jiaxiang Li ◽  
Biao Wang ◽  
Jian Sun ◽  
Shuhong Wang ◽  
Xiaohong Zhang ◽  
...  
Keyword(s):  
Finite Element ◽  
Transmission Lines ◽  
Progressive Collapse ◽  
Element Model ◽  
Transmission Tower ◽  
Line System ◽  
Finite Element Software ◽  
Transmission Towers ◽  
Ice Shedding ◽  
The Impact

Ice shedding causes transmission lines to vibrate violently, which induces a sharp increase in the longitudinal unbalanced tension of the lines, even resulting in the progressive collapse of transmission towers in serious cases, which is a common ice-based disaster for transmission tower-line systems. Based on the actual engineering characteristics of a 500 kV transmission line taken as the research object, a finite element model of a two-tower, three-line system is established by commercial ANSYS finite element software. In the modeling process, the uniform mode method is used to introduce the initial defects, and the collapse caused by ice shedding and its influencing parameters are systematically studied. The results show that the higher the ice-shedding height is, the greater the threat of ice shedding to the system; furthermore, the greater the span is, the shorter the insulator length and the greater the dynamic response of the line; the impact of ice shedding should be considered in the design of transmission towers.

scholarly journals Сombined ships stability analysis at the stage of design study

2021 ◽  
pp. 29-35
Author(s):  
Ilya A. Gulyaev Gulyaev ◽  
Evgeniy P. Ronnov
Keyword(s):  
Stability Analysis ◽  
Optimization Problems ◽  
Mutual Influence ◽  
Static Stability ◽  
Wind Effect ◽  
Stability Assessment ◽  
Design Study ◽  
Hull Design ◽  
The Stability ◽  
Russian River

. A method of stability analysis for combined ship (oil carrier/platform ship type) at the stage of design study is presented. It should be noted that not all of ship’s main seaworthiness and operational characteristics are the result of a simple addition of the characteristics of an oil carrier and a platform ship. Their mutual influence takes place, which should be taken into account when analysing the stability in the multivariant optimization problems of internal and external design of such ships. This leads to the requirement to adjust the known methods of stability analysis at the initial stages of ship design, which was the purpose of the present work and its originality. Taking into account the multivariance of the task and the hull design type, the stability assessment will be carried out through the analysis of the metacentric height extreme value on the assumption that the requirements of Russian River Register for admissible heeling angle at static wind effect are met. In order to account for nonlinearity of static stability curve when inclining up to the angles of deck immersion into water and emergence of bilge, it is suggested to apply an approximate method of metacentric radius determination. The proposed method of combined ship stability assessment is recommended to apply at the stage of justification and analysis of ship’s key elements as a limitation in the problems of mathematical modeling of optimization of such type of ships. The method allows to exclude from further consideration at the design study stage the possible options that do not meet the requirements of seaworthiness.

Walking Stability Analysis of Multi-Legged Crablike Robot over Slope

2013 ◽  
Vol 572 ◽  
pp. 636-639
Author(s):  
Xi Chen ◽  
Gang Wang
Keyword(s):  
Mathematical Model ◽  
Stability Analysis ◽  
Stability Criterion ◽  
Stability Margin ◽  
Static Stability ◽  
Matlab Simulation ◽  
And Performance ◽  
The Stability ◽  
The Mathematical Model ◽  
The Relationship

This paper deals with the walking stability analysis of a multi-legged crablike robot over slope using normalized energy stability margin (NESM) method in order to develop a common stabilization description method and achieve robust locomotion for the robot over rough terrains. The robot is simplified with its static stability being described by NESM. The mathematical model of static stability margin is built so as to carry out the simulation of walking stability over slope for the crablike robot that walks in double tetrapod gait. As a consequence, the relationship between stability margin and the height of the robots centroid, as well as its inclination relative to the ground is calculated by the stability criterion. The success and performance of the stability criterion proposed is verified through MATLAB simulation and real-world experiments using multi-legged crablike robot.

Static Stability of Floating Units in Operational Conditions: A Physics-Driven Approach

2017 ◽  
Author(s):  
Neil Luxcey ◽  
Øystein Johannessen ◽  
Sébastien Fouques
Keyword(s):  
Static Stability ◽  
Stability Study ◽  
Operational Stability ◽  
Physical Models ◽  
Floating Platform ◽  
Line System ◽  
Operational Conditions ◽  
Axis Of Rotation ◽  
Numerical Tool ◽  
The Stability

When designing a new floating unit concept, static stability computations are performed in order to check stability criteria defined in regulations. Calculations for design conditions generally include the estimation of buoyancy force, gravity force and wind force acting on the floater for a given condition and a desired axis of rotation. However, when studying the stability of a floating platform in operational conditions, all external forces acting on the unit should be comprised in the assessment in order to get a more realistic — and even physically admissible — picture of the platform stability. Those forces include among others wind, current and anchor line system forces. In addition, limiting the study to one axis of rotation may not provide a complete picture of the floater stability, especially when the hull is of a semi-submersible type. Following this physical approach, a numerical tool has been developed based on the SINTEF Ocean’s SIMA software package. The latter package initially includes a time domain simulator of complex multibody systems for marine operations. The developed tool provides accurate physical models for each force component that may have effects on the stability. It opens the possibility to study the operational stability of a floater without restraining the study to one axis of rotation. It also allows the analysis of damaged conditions with large inclination angles. This paper describes the model implemented in this numerical tool. Validation work is presented for simple geometries. Results from an operational stability study of a semi-submersible are discussed. Finally, possible further work is discussed.

Maximizing Walking Step Length for a Near Omni-Directional Hexapod Robot

2004 ◽  
Author(s):  
James P. Schmiedeler ◽  
Nathan J. Bradley ◽  
Brett Kennedy
Keyword(s):  
Stability Analysis ◽  
Step Length ◽  
Static Stability ◽  
Optimization Approach ◽  
Computationally Efficient ◽  
Constant Height ◽  
Planning Algorithm ◽  
Two Phases ◽  
The Stability ◽  
Path Planning Algorithm

A foot path planning algorithm is presented for a robot with six limbs symmetrically located on the faces of its hexagonal body, enabling it to walk at a constant height with an alternating tripod gait. The symmetry results in near omni-directional locomotion capability, so the algorithm is formulated for walking in any direction and at any height. The approach is to determine the maximum length foot path through each limb’s workspace and then modify those foot paths based upon static stability analysis. The stability analysis is conducted in two phases to ensure stability without excessively reducing step length. Compared to an optimization approach, the algorithm yields foot paths within 9.1% of the maximal foot paths for all directions and heights. Unlike the optimization approach, the developed algorithm is computationally efficient enough to be implemented in realtime.

RESEARCH OF THE STABILITY ANALYSIS FOR FRAME BUILDINGS USING FINITE ELEMENT METHOD

2019 ◽  
Vol 7 (1) ◽  
pp. 45-48
Author(s):  
Галина Кравченко ◽  
Galina Kravchenko ◽  
Елена Труфанова ◽  
Elena Trufanova ◽  
Анастасия Бойко ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Stability Analysis ◽  
Design Method ◽  
Progressive Collapse ◽  
Structural Member ◽  
Mode Shapes ◽  
Frame Buildings ◽  
The Stability ◽  
Element Method

In this article, general stability analysis is considered, in order to obtain the load-bearing capacity of the multy-storey building using finite element method. There are some graphical interpretations for FE results that illustrate safety factor for each structural member of the structure and different mode shapes with their corresponding frequencies. These results can be used to improve the structural member design method in case of progressive collapse possibility. The article provides recommendations for strengthening and design of structural member.

The Stability Analysis on the Different Types of Single Layer Latticed Shell

2013 ◽  
Vol 788 ◽  
pp. 598-601
Author(s):  
Jun Qiang Wu ◽  
Yu Cui
Keyword(s):  
Stability Analysis ◽  
Static Load ◽  
Single Layer ◽  
Static Stability ◽  
Different Types ◽  
Practical Engineering ◽  
Small Structure ◽  
The Stability ◽  
Lattice Shell ◽  
Better Than

This single-layer spherical reticulated shell has the advantages of reasonable stress,beautiful appearance ,fast construction,is widely applied in practical engineering. Through the static stability analysis of three kinds of single-layer spherical lattice shell structure using ansys, we get them in the uniform deformation under static load, the modal, buckling load. The results show that: The Kiewitt latticed shells displacement is small, structure is stable, better than SchwedLer and lianfang.

Wind-Induced Progressive Collapsed Performance of Cup-Type Transmission Tower-Line System

2013 ◽  
Vol 353-356 ◽  
pp. 2392-2396
Author(s):  
Zhuo Qun Zhang ◽  
You Xin Lin ◽  
Hong Nan Li
Keyword(s):  
Progressive Collapse ◽  
Finite Element Models ◽  
Strong Wind ◽  
Transmission Tower ◽  
Line System ◽  
System Collapse ◽  
Simulation Results ◽  
Element Technique ◽  
Simulated Wind ◽  
Collapse Process

The Cup-type transmission tower-line system was a classic representative of high voltage electric power carrier, which was an important lifeline project. However, it frequently collapsed under different environmental loadings, especially strong wind. In this work, four tower five line finite element models simulated wind-induced progressive collapse process by birth-to-death element technique in ABAQUS/Explicit. The numerical simulation results demonstrated that this application could describe the structural collapse performance clearly and effectively and transmission tower-line system collapse path depended on the number, position and last deformation of damage elements.

Progressive Collapse of Power Transmission Tower-Line System Under Extremely Strong Earthquake Excitations

2016 ◽  
Vol 16 (07) ◽  
pp. 1550030 ◽  
Author(s):  
Li Tian ◽  
Rui-sheng Ma ◽  
Hong-nan Li ◽  
Yang Wang
Keyword(s):  
Power Transmission ◽  
Progressive Collapse ◽  
Three Dimensional ◽  
Coupled System ◽  
Element Model ◽  
Single Component ◽  
Transmission Tower ◽  
Line System ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

The simulation of progressive collapse of a power transmission tower-line system subjected to extremely strong earthquakes is studied in this paper. A three-dimensional finite element model is established for the coupled system that combines three towers and four span lines based on a practical project. The birth to death technique is adopted to simulate the progressive collapse of the system by using the user subroutine VUMAT in ABAQUS. The simulation of progressive collapse of the transmission tower-line system under either single-component or multi-component earthquake excitations is conducted. The collapse path, fracture position and collapse resistant capacity of the transmission tower are investigated. The result shows that the effect of multi-component seismic excitations should be taken into account in simulation of progressive collapse of the transmission tower, since the behavior of towers under multi-component excitations is different from that of single-component excitations. In addition, incremental dynamic analysis (IDA) is carried out to verify the results obtained herein. The present result should prove useful to the seismic design of power transmission towers.

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