Deformation Of Cables Research Articles

Numerical Modeling for Collapse Analysis of Cable-Stayed Bridges using the Improved Applied Element Method

This work presents a novel numerical simulation of the collapse process of cable-stayed bridges based on the improved applied element method, which was originally developed as an effective numerical tool for large-scale framed structures under severe loading circumstances. For that, a straight spring element type is utilized for modeling the stay-cable with an equivalent modulus of elasticity that combines the effects of material and geometric deformation of the bridge cables. Moreover, the advantage of the multi-layered element type, which allows for the modeling of various rectangular or non-rectangular RC and composite sections without any complications, is utilized for modeling the pylon and the deck. The pretension forces in the cables are applied by adding an initial loading procedure in which the stay-cable is exposed to an initial strain to consider the effect of prestressing. The mass matrix is modified to include the stay-cable mass, which is lumped at the centroid of the elements connected by the stay-cable. The proposed modeling approach takes material and geometric nonlinearities into account for both the multi-layered element and the stay-cable. Verification examples are provided to examine the capability of the model. The comparison between the results of the proposed modeling technique and the finite element results has shown good agreement, highlighting the reliability of the proposed modeling technique. In addition, the developed tool is used to carry out collapse analysis of a cable-stayed bridge under a cable-loss scenario to examine the capability of the proposed technique.

Simulation and Analysis of Arc-drop Deformation of High-voltage Cables with Three-dimensional Laser Scanning Point Cloud

In order to investigate the influence of environmental factors on the deformation problems occurring in high voltage cables, this paper proposes a method for analyzing the deformation of high voltage cables based on 3D laser scanning. Firstly high voltage cable point cloud data is acquired. Secondly, a single power line is segmented using a density-based clustering method, and a mathematical model of the high-voltage cable is established using the least squares method. Then the high-voltage cable is downscaled from three-dimensional points to two-dimensional points to do the fitting of parabola on the plane. Finally compare the horizontal displacement and vertical displacement of the lowest overhanging point of the high-voltage cable with the weather to affect its deformation causes. The experimental results show that: the parabolic approximate fitting equation of the high voltage cable can accurately express the shape of the cable, and the R value of the equation is around 0.999. The vertical displacement of the high-voltage cable in the high-temperature and high humidity environment changes significantly, up to 0.556 m. Horizontal displacement is significantly affected by the wind, the wind in the 7mph horizontal displacement change is the largest, the average displacement change of 0.197m.

A New Composite Control Strategy for an Astronaut Virtual Operation Training System Based on Cable-Driven Technology

In recent years, virtual microgravity training technology for astronauts based on cable-driven designs has emerged, and it solves the following problems: high costs, short training times, and low safety of existing equipment. However, this technology does not solve the reduced motion accuracy problem of the operated object due to the elastic deformation of cables, and this problem will reduce the operational experience of astronauts during training. In view of this problem, a cable-driven virtual operation training system for astronauts is designed, and a new composite control strategy based on parallel cables is proposed, which effectively improves motion control accuracy by allocating cable tension and using a tension compliance control method to suppress the influence of cable deformation. In addition, the desired tension of cables is optimized based on the system’s workspace so that the system can achieve more complex virtual microgravity training tasks. Finally, verification via experiments demonstrated that the training system and the new composite control strategy are effective.

Manipulation Planning for Wiring Connector-Attached Cables Considering Linear Object’s Deformability

In this paper, we propose a method of manipulation planning for cable wiring. The method enables to take into account the deformation of cables while connector incorporation process. Using a physical simulation that predicts the shape of a cable based on the pose of both ends of the cable, we generate a connector moving path that avoids intereference between the cable and surrounding structures. We conducted experiments under several different environments and several different lengths of cables, and confirmed that actual cable manipulation can stably be achieved by using the proposed method.

Determination of the Design Parameters of SMA Cables for Self-Centering Frame Structures

In order to improve the force performance of traditional anti-buckling energy dissipation bracing with excessive non-recoverable deformation caused by strong seismic action, this paper presents a prestress-braced frame structure system with shape memory alloy (SMA) and investigates its deformation characteristics under a horizontal load. Firstly, this paper establishes a theoretical analysis model by analyzing the geometric relationship between the deformation of SMA cables and inter-story displacement based on the internal force balance equation. The model is used to solve the anti-lateral displacement stiffness of the SMA cable-supported frame structure and to derive a reasonable formula for calculating the initial prestress and cross-sectional area of SMA cables. Then, the mechanical behavior of the SMA cable-supported frame structure system under an equivalent horizontal load is simulated using ABAQUS software and compared with the calculated results of conventional tie-supported and non-dissipative-supported frame structures. The results show that the force performance of the frame structure system determined by the SMA cable design method proposed in this paper is significantly improved under the horizontal load. Furthermore, it can ensure a certain ductility requirement of the frame structure system, which verifies the effectiveness of the design method of the SMA cable frame structure system proposed in this paper.

Analytical solutions for thermal effects of suspension bridges based on a surrogate model with longitudinal restraint stiffness

Ambient temperature variation has a significant influence on the deformation of main cables and the internal force of towers of long-span suspension bridges. Currently, the finite element method (FEM) is mainly used for these calculations. This paper intends to present an analytical solution of the thermal effects on suspension bridges. First, three typical temperature patterns are defined. Then, a surrogate model is established by replacing the longitudinal restraint stiffness of the main cable and the tower lateral stiffness with a set of equivalent horizontal springs. The stiffnesses of the suspended cables are formulated according to the energy conservation principle, while the tower lateral stiffnesses are obtained by incorporating the pure bending and Euler buckling solutions, namely considering the effect of the axial force placed on the tower top. Following the force equilibrium conditions, two governing equations are built, which can calculate the variations in the longitudinal displacement of the tower top caused by the temperature variation. After that, some other significant thermal effects, such as the horizontal force of the main cable, the sag of the main cable and the bending moment of the tower bottom, are obtained. Finally, the analytical solution is verified through the field test data of the Tsing Ma Bridge in Hong Kong and the FEM results of four typical examples. The proposed surrogate model offers a quick and easy approach for thermal effect analysis with acceptable accuracy. It is helpful to clarify the mechanical nature of temperature effects to facilitate the preliminary bridge design.

A hamiltonian global nodal position finite element method for dynamics analysis of submarine cables

The dynamics of submarine cables can be expressed in Hamiltonian formalism, which can reduce the error accumulation over long-term numerical calculation. This paper proposes a Hamiltonian global nodal position finite element method to study the dynamic responses of submarine cables undergoing bending deformation and long-term large overall motions. The new global nodal position finite element discrete formulation is derived by Hamiltonian theory and Euler-Bernoulli beam theory, which takes the bending deformation of submarine cables into consideration. To verify the proposed method, the second-order Symplectic difference algorithm is built for numerical solution. Five-point Gauss-Legendre quadrature formulate is applied to calculate the hydrodynamic force. The calculation accuracy and efficiency of the proposed method are validated by the freefall cantilever test of submarine cable, the towing test of submarine cable with lumped mass, the motion simulation of submarine cable connected to the remotely operated vehicle (ROV) and the towing test of a submerged body. Compared with the existing Hamiltonian nodal position finite element method, all validations and results indicate that the proposed method can solve the motion of various submarine cables under different working conditions with higher accuracy and efficiency.

Support characteristics of flexible negative Poisson’s ratio anchor cable response to blasting impacts

With the gradual decrease and exhaustion of shallow mineral resources, underground mining has progressed to greater depths. Here, the geological environment is significantly more complex and nonlinear, and large deformations of rock masses have great potential to occur. Many geotechnical engineering disasters have occurred even while using Poisson’s ratio (PR) anchor cable supports. To efficiently deal with these issues, a new support material called negative Poisson’s ratio (NPR) anchor cable is proposed; this material can withstand large deformations and provide high constant resistance. In this study, the support characteristics of macro-NPR anchor cable under blasting impact were mainly studied. The support effects of PR anchor cable and macro-NPR anchor cable were compared and analyzed with the help of field experiments and numerical simulations. The results indicate that field experiments and discontinuous deformation analysis accurately reflect the failure state of the selected roadway, as well as the tension and deformation of the anchor cables. The roadway supported by PR anchor cables cannot resist rock bursts under ordinary circumstances. However, the NPR anchor cable-supported roadway resisted a rock burst caused by the impact equivalent to a mine earthquake magnitude above 3; it meets the requirements of roadway stability.

水中パラレルワイヤ駆動システムのモデル化と制御

Cable-driven parallel robots are mechanisms that control the position and attitude of an object using multiple cables. Typical cable-driven parallel robots have been studied for use on land, but not for use in water. This is because the position and attitude control of object and motion analysis become difficult underwater due to the large deformation of cables caused by fluid forces. In this paper, we propose an underwater cable-driven parallel robot consisting of multiple on-water robots and derive a dynamics model that considers the cable dynamics underwater. Then, we proposed a position and attitude control system for the suspended object based on the inverse kinematics problem for the suspended object and studied its effectiveness by simulation by using the planar two degrees-of-freedom underwater cable-driven parallel robot.

Deformation of stainless steel cables at elevated temperature

The deformation of stainless steel cables at elevated temperatures is an important consideration for the design of fire resistant pre-stressed spatial structures. In this paper, by conducting extensive experiments on a number of specimens, the thermal expansion under a stress-free state, the deformation under thermo-mechanical coupling state in transient heating stage, and the creep deformation in constant temperature stage of stainless cables subjected to elevated temperature were studied experimentally. A correlation for the thermal expansion coefficient of the stainless steel cables in the range of 30–600 °C was obtained. In addition, an equation relating the deformation of the cables and the temperature and initial stress under the thermo-mechanical coupling state in the heating stage was proposed. Furthermore, the relationship between the parameters of the Field & Field creep model and the temperature was derived for the stainless steel cables.

Dynamic Modeling and Residual Vibration Suppression of the Redundantly-Actuated Cable Driving Parallel Manipulator

An improved input shaping (IS) scheme was proposed for the redundantly actuated cable driving parallel robots (CDPRs) to suppress the residual vibration (RV). To make the design of the RV suppression convenient, the flexible displacements of the moving platform were taken as the generalized coordinates considering the axial deformation of cables, and rigid-flexible dynamic model of generalized redundantly actuated CDPRs was established with the Newton-Euler equation and the Newton's law. Then to cope with time-variant vibration frequencies of the CDPRs due to the variable lengths of cables, the technique that combined the one- to three-order zero vibration (ZV) IS with the particle swarm optimization (PSO) and the controller was proposed to suppress the RV. At last, to validate the effectiveness the proposed method, the simulations were carried out in a redundantly actuated CDPR that has six degree-of-freedom CDPR and seven driving cables with the proposed method, the results show that the RVs can be reduced significantly.

In-situ repair/maintenance with a continuum robotic machine tool in confined space

In-situ repair/maintenance is critical for the key industry sectors (e.g. aerospace, nuclear), which require prompt interventions. The paper reports on a tendon driven continuum robotic machine tool with high manoeuvrability in navigating and machining within confined workspaces. The design reveals the main working principles of the robotic machine tool, followed by its calibration method and a new kinematics compensation approach to account for the deformation of the actuation cables that is that the key enabler for its use in machining tasks, which is based on the geometry of the actuation system. Finally, a set of experimental trials were conducted to show its ability to perform in-situ accurate machining operations in a mock-up aerospace scenario.

Disturbance Effects by Excavation of Neighboring Roadways in Deep Coal Mine

Numerical simulation method and on-site dynamic monitoring are used to study a railway laneway disturbed by excavation of neighboring roadways under high in-situ stress in a deep coal mine of Huainan region. The paper presents a series of variation trend about stress state, deformation, plastic zone and tension of cables under disturbance effects based on the simulation results, and the evolution of surface displacement of railway laneway is also discussed according to on-site monitoring data. The analysis shows that disturbance effects have spatiotemporal characteristics and support structure should be installed in a short time which helps to reduce disturbance by construction of adjacent caverns.

Static Stiffness Analysis of Flexible-cable-driven Parallel Mechanism

The static stiffness of flexible-cable-driven parallel mechanism is studied and its theoretical formulation of the calculation model is deduced. The results show that the static stiffness matrix of flexible-cable-driven parallel mechanism can be decomposed into two parts. k1 results from the changes of position and orientation of the movable platform which correlates with cable tensions, while k2 is caused by the deformation and deflection of cables. The study further proves that the static stiffness of completely restrained positioning mechanism (CRPM) or redundantly restrained positioning mechanism (RRPM) mainly depends on k2. It is only affected by the elastic performances of all cables and the Jacobian matrix which represents the vectors of cable forces, and unrelated with the amplitudes of cable tensions. For the incompletely restrained positioning mechanism (IRPM), because of the existence of cable catenaries the static stiffness not only correlates with the elastic performances of all cables and the Jacobian matrix, but also the amplitudes of cable tensions. Two examples concerning the static stiffness estimation are given for RRPM and IRPM(the cable-driven cabin suspension of the five-hundred-meter aperture spherical telescope)respectively. The comparison between the analytical and simulation results proves the validity of the calculation model.

Finite Element Analysis of Cable Products for High Impaction and Fatigue Resistance with Nonlinear Material Models

This paper presents experimental and numerical simulation for deformation and fatigue life prediction of various cables, such as electrical, optical and network cables. The cable damage is produced by the tensile, bending and torsional action under moving and fixing condition, and by direct external impact. To obtain material responses of the cable, uniaxial tensile tests and drop-weight impact tests were adopted, and the nonlinear constitutive equations based on various strain energy potentials or material models were employed to analyze deformation of polymer sheath and metallic armor layer of the cable. Finite element results were compared with experimental data for deformation and impact absorption energy of the cable during direct external impact. Also, fatigue strength of the cable was predicted from variation of calculated stress level under tensile conditions. Fractured surface of the cable were analyzed by scanning electron microscopy (SEM).

係留索の動的挙動を考慮した完全没水浮体の振動特性

In case of completely submerged floating structure, no change in buoyancy can beexpected with its dynamic motion and the restoring force fully depends on cables. Consequently, it is necessary to seize the relation between structural displacement and restoring force and to evaluate the effect ofnonlinear deformation of cables on the dynamic response. This study aims to evaluate the effect of deformation of mooring cable caused by self-weight, inertia and fluid force on the vibration of the structure. This paper introduces nonlinear equations of motion considering the dynamic behavior of the cables and investigates the effect of dynamic deformation of cables on whole behavior with numerical examples.

Guidance of oligodendrocytes and their progenitors by substratum topography

Oligodendrocyte progenitors arise in subventricular zones and migrate extensively during development before differentiating into mature oligodendrocytes, which myelinate nerve tracts in the central nervous system. We have used microfabricated substrata, containing periodic patterns of contours similar to those of central nervous system axons to assess the influence in vitro of substratum topography on oligodendrocytes isolated from 7 day rat optic nerve. Antiganglioside antibody A2B5 positive oligodendrocyte-type 2 astrocyte progenitors, and galactocerebroside positive and myelin basic protein positive oligodendrocytes, were highly aligned by surface contours as small as 100 nm depth and 260 nm repeat spacing. Rat optic nerve astrocytes also aligned on surface contours, but rat hippocampal and cerebellar neurons were unresponsive. Oligodendrocytes demonstrated enhanced parallel extension of their processes on narrow repeating topography in an arrangement similar to that found in the intact optic nerve. This is in marked contrast to the phenotype displayed by this cell type on planar substrata. Neither oligodendrocytes nor oligodendrocyte-type 2 astrocyte progenitors showed high-order F-actin cytoskeletal networks; thus their alignment on gratings is unlikely to result from deformation of actin cables and focal contacts. In contrast, aligned astrocytes showed striking arrangements of actin stress fibres. These results establish glial cells as potentially the most topographically sensitive cell types within the central nervous system. Furthermore, the topographical pattern inducing maximal alignment of oligodendrocyte lineage cells corresponds to the diameters of single axons within the 7 day optic nerve. Thus the migration of oligodendrocyte-type 2 astrocyte progenitors and axonal ensheathment by oligodendrocytes may be guided by axonal topography within the developing nerve.

Microcomputer-aided design of tensile roof structures

This paper presents interactive microcomputer-aided design of tensile roof structures. A highly interactive multi-window system has been developed on an IBM PS 2 Model 80 for the design of three different classes of cable roof structures: freely suspended synclastic-surface (dish-shaped) nets, prestressed flat nets, and prestressed anticlastic-surface (saddle-shaped) nets. Graphic displays of cable roof structures include various perspective views of the structure, deformed shape of the structure, and deformation of individual cables.

Principles of time domain reflectometometry applied to measurement of rock mass deformation

Time Domain Reflectometry (TDR) is an electrical pulse testing technique originally developed to locate faults in coaxial power transmission cables. Recently, this technique has been adapted for monitoring deformation of cables grouted into rock masses. Rock mass movements deform the grouted cable, which locally changes cable capacitance and thereby the reflected wave form of the voltage pulse. By monitoring changes in these reflection signatures, it is possible to monitor both local extension and local shearing. This paper concentrates on the electromagentic wave theory necessary to quantitatively relate changes in cable geometry to changes in reflected voltage signatures. A finite element model is employed to numerically simulate capacitance changes for deformed geometries produced in the laboratory, and the effect of signal attentuation and resolution of two deformities is assessed on the basis of laboratory test results. Finally, these models are employed to extract heretofore unrealized information from previously from previously collected field data.