Cable Simulation Research Articles

Research on Assembly Technology of Complex Flexible Outcabin Motional Cable for Spacecraft

Based on the application of flexible cable assembly simulation analysis technology in complex flexible out-cabin motional cable assembly of spacecraft, the working environment and physical characteristics of flexible motional cable are analyzed, reasonable assembly constraints are planned, and cable assembly simulation analysis is described in detail. The research results not only ensure the accuracy and practicability of the design, but also reduce the assembly defects and product failure rate. The actual effect of cable assembly can be accurately judged, the product performance can be improved, the product development cycle can be saved, and the development cost can be significantly reduced.

Trade study to select best alternative for cable and pulley simulation for cranes on offshore vessels

AbstractCranes on offshore vessels are subjected to crane dynamics, structural couplings to the vessel, and environmental influence by waves and currents. The recent trend has been to use larger cranes on smaller vessels, which makes the lifting operation more complex and potentially dangerous. The use of digital twins (DTs) is emerging as one way to enable safer operations, real‐time simulation, and maintenance prediction. On offshore vessels, a DT can monitor the lifting operation to create a safer work environment. The SPADE (stakeholders, problem formulation, alternatives, decision making, and evaluation) model has been used as a framework toward the creation of a DT of cranes on offshore vessels. Several cases involving simulation of cranes revealed the lack of an adequate simulation of cable and pulleys suitable for use in a DT. The simulation is important for accurate results and for implementation in control systems. A trade study was performed to determine a numerical method adequate for cable and pulley simulation. The trade study identified the absolute nodal coordinate formulation in the framework of arbitrary Lagrangian–Eulerian as a promising numerical formulation.

Transient Simulation and Recovery Time of a Three-Phase Concentric HTS Cable

In this paper, we investigate by means of transient simulations a three-phase high-temperature superconducting cable similar to the AmpaCity project under fault conditions. The objective is to investigate if the increase of temperature during the fault period may result in permanent damage to the cable. We consider a three phase to the ground fault situation. A two-dimensional computational heat transfer analysis is carried out to simulate the transient thermal behavior of the cable. The result shows that the cable may return to operation after about 20 s. The recovery time of the coolant is about 8 h.

Machine learning in drug development: Characterizing the effect of 30 drugs on the QT interval using Gaussian process regression, sensitivity analysis, and uncertainty quantification

Prolonged QT intervals are a major risk factor for ventricular arrhythmias and a leading cause of sudden cardiac death. Various drugs are known to trigger QT interval prolongation and increase the proarrhythmic potential. Yet, how precisely the action of drugs on the cellular level translates into QT interval prolongation on the whole organ level remains insufficiently understood. Here we use machine learning techniques to systematically characterize the effect of 30 common drugs on the QT interval. We combine information from high fidelity three-dimensional human heart simulations with low fidelity one-dimensional cable simulations to build a surrogate model for the QT interval using multi-fidelity Gaussian process regression. Once trained and cross-validated, we apply our surrogate model to perform sensitivity analysis and uncertainty quantification. Our sensitivity analysis suggests that compounds that block the rapid delayed rectifier potassium current IKr have the greatest prolonging effect of the QT interval, and that blocking the L-type calcium current ICaL and late sodium current INaL shortens the QT interval. Our uncertainty quantification allows us to propagate the experimental variability from individual block-concentration measurements into the QT interval and reveals that QT interval uncertainty is mainly driven by the variability in IKr block. In a final validation study, we demonstrate an excellent agreement between our predicted QT interval changes and the changes observed in a randomized clinical trial for the drugs dofetilide, quinidine, ranolazine, and verapamil. We anticipate that both the machine learning methods and the results of this study will have great potential in the efficient development of safer drugs.

Tropomyosin Cable Formation and Its Influence on the Structural Dynamics of Tropomyosin

Head-to-tail association of coiled-coil tropomyosin dimers produce four-helix bundle “overlapping domains” connecting the dimers together. This polymerization process yields elongated super-helical cables that interact continuously with the surface of the actin filament. While considerable computationally generated information is available on the local and global interactions between isolated (unpolymerized) tropomyosin dimers and F-actin (Li et al., 2011), little is known about the influence of the overlapping domain on the structural-mechanics of tropomyosin and hence corresponding tropomyosin behavior on actin filaments. In an effort to elucidate localized overlapping domain - actin interaction and ensuing regulatory translocation across actin, we compared molecular dynamics simulations of models of single dimeric tropomyosin molecules (as in Li et al., 2010) with new models of tropomyosin cables. The simulations of tropomyosin cables were performed with the tropomyosin polymer constrained to a native super-helical configuration as if linked to a ghost F-actin filament at a radius of 39 Å, thereby maximizing native flexural and twisting motions without being dampened by interaction with F-actin. We have recently shown that torsional motions and sequence-dependent twisting of tropomyosin is initiated and propagated from aspartate-137 and surrounding amino acids and is critical for tropomyosin function (Lehman et al., 2018). We now have shown that the sequence-specific twisting pattern of tropomyosin is virtually unaffected by the additional presence of the overlapping domain, while the flexural motions of tropomyosin are dampened as expected. In addition, related MD shows that torsional (and flexural) mobility of the overlapping domain itself appears to be unaffected by the presence of the remainder of the molecule. We conclude that the material properties of tropomyosin are dominated by its dimeric coiled-coil region and that the main function of overlapping domain is to sponsor tropomyosin polymerization and cable formation.

A comparison between single and double cable neuron models applicable to deep brain stimulation

Computational models for activation assessment in deep brain stimulation (DBS) are commonly based on neuronal cable equations. The aim was to systematically compare the activation distance between a single cable model implemented in MATLAB, and a well-established double cable model implemented in NEURON. Both models have previously been used for DBS studies. The field distributions generated from a point source and a 3389 DBS lead were applied to the neuron models as input stimuli. Simulations (n = 670) were performed with intersecting axon diameters (D) between the models (2.0, 3.0, 5.7, 7.3, 8.7, 10.0 μm), variation in pulse shape and amplitude settings (0 to 5 in increments of 0.5 mA or V) with the single cable model as reference. Both models responded linearly to change of input (point source: 0.93 < R2 < 0.99, DBS source: R2 > 0.98), but with a systematic extended activation distance for the single cable model. The difference for a point source ranged from −0.2 mm (D = 2.0 μm) to −1.1 mm (D = 5.7 μm). For the DBS lead a D = 3.2 μm agreed with the commonly used double cable simulations D =5.7 μm in voltage mode. Possible reasons for the deviation at larger axons are the internodal length, the ion channel selection and physiological data behind the models. The single cable model covers a continuous range of small axon diameters and calculated the internodal length for each iteration, whereas the double cable models uses fixed defined axon diameters and tabulated data for the internodal length. Despite different implementations and model complexities, both models present similar sensitivity to pulse shape, amplitude and axon diameter. With awareness of the strength and weakness both models can be used to extract activation distance used to relate a specific electric field isolevel and thus estimate the volume of tissue activated in DBS simulation studies.

A methodology for design and fatigue analysis of power cables for wave energy converters

The recent development of subsea power cables for various offshore marine renewable energy technologies has identified the need for new cables that have low structural stiffness properties. This type of cable is referred to as dynamic cable because of its high bending flexibility compared to static cables. The current study presents a cable design model and simulation models that were developed for the design and fatigue analysis of dynamic cables. These models were applied on a subsea dynamic power cable with a design that is suitable for a floating point-absorbing wave energy converter (WEC), where the cable must withstand cyclic loads imposed by the motions of the WEC, the waves and the ocean currents. The cable design model is presented with its detailed design and dimensioning methodology for cables with multiorder helical structures, with respect to desired (target) mechanical properties. The cable design model is verified against a verification study in the literature. A simulation model of a fatigue test rig for accelerated rotational bending is presented. The results from the numerical simulations and the subsequent fatigue analyses are compared against results from experiments using the test rig. The influence of the dynamic effects and mechanical properties on the fatigue life of the cable is discussed. This study contributes to a better understanding of the fatigue failure mechanisms of the cable, and it also highlights the importance of further development of numerical models.

Experimental Study of The Dynamic Response of a Cable Under Wind Flow

Nowadays, the high quality of available building materials, powerful machinery and high precision construction techniques allow us to build bridges with very long spans at efficient costs. Depending on the site and the spans, the most common solutions for these types of structures are arch bridges, cable stayed bridges, suspension bridges and even variations among the three. Because of their size and the nature of the crossed obstacles, these types of structures can be very difficult to access outside the carriageways or the pavements and so, inspection maintenance works are very difficult and costly. One critical structural element which is common for all these bridges are the cables. They are out in the open, exposed to a wide variety of phenomena which can cause them damage. Although they perform exceptionally well under tensile forces in longitudinal directions, they are very weak and prone to take damage under transverse loads. For example, it has been observed, that long cable stays tend to vibrate uncontrollably. If left uncheck, these vibrations can resonate and cause damage to the protective sheath, anchorages and even the cables themselves, eventually leading to their collapse. In order to prevent this, engineers must take into account the various mechanisms that can cause vibrations, determine their effect on the stays, and find ways to mitigate them in order to reduce the amplitudes under acceptable levels. Cable vibration simulation using numerical models is very difficult to do, due to the high degree of uncertainty, large volume of processing to be done and lack of validation methods for the results. This paper presents a scaled model analysis of a cable stay in a wind tunnel where vibrations are measured under different wind speeds. Finite element models of the cable are then done, using the measurements to correct certain design parameters in order to improve the precision of the calculated results

A Generalized Simulation Framework for Tethered Remotely Operated Vehicles in Realistic Underwater Environments

This paper presents a framework for simulating visually realistic motion of underwater Remotely Operated Vehicles (ROVs) in highly complex models of aquatic environments. The models include a wide range of objects such as rocks, fish and marine plankton in addition to an ROV tether. A modified cable simulation for the underwater physical conditions has been developed for a tethered ROV. The simulation framework also incorporates models for low visibility conditions and intrinsic camera effects unique to the underwater environment. The visual models were implemented using the Unreal Engine 4 realistic game engine to be part of the presented framework. We developed a generalized method for implementing an ROV dynamics model and this method serves as a highly configurable component inside our framework. In this paper, we explore the unique characteristics of underwater simulation and the specialized models we developed for that environment. We use computer vision algorithms for feature extraction and feature tracking as a probe for comparing experiments done in our simulated environment against real underwater experiments. The experimental results presented in this paper successfully demonstrate the contribution of this realistic simulation framework to the understanding, analysis and development of computer vision and control algorithms to be used in today’s ROVs.

Revisiting the homogenized domain model for fast simulation of AC transport power losses in first generation high temperature superconducting tapes and cables

Challenges, linked with FEM modelling of HTS power cables, include the long computational time required to simulate the small domains that Bi-2223 superconductors possess in a large device. To decrease that time, in this paper the models of AC transport power losses for a tape and a simplified cable are achieved by a homogenization technique via a ”filamentary-equivalent domain” approach. In it, a single homogenous domain with effective material properties is used to represent the superconducting material, where the domain would have the approximate shape of the multifilamentary region. In order to investigate its validity for a range of transport currents, including overcurrent, four tapes from the literature are modelled in three configurations. A simplified cable model is modelled via the homogenized model and an analytical equivalent circuit model. The homogenization technique can accurately predict the transport power losses of the majority of configurations while demonstrating fast computational times and is promising for simulation of real power cables.

Innovative CAD-integrated Isogeometric Simulation of Sliding Edge Cables in Lightweight Structures

The focus of the paper is twofold: About the practical structural problem of membrane structures mechanically prestressed by edge cables, which are allowed to slide tangentially, and about an innovative CAD integrated simulation technique. The structural problem is well recognized but the new technique most elegantly resolves the challenges of standard discretization approaches when dealing with the formulation and solution of the sliding contact of two bodies discretized by individual, non-matching meshes moving relatively to each other. The proposed formulation takes advantage of the parameter space of NURBS patches and extends the weak coupling formulation by adding a degree of freedom in the parameter space and thus inherently satisfies the sliding constraints. Indeed, the presented contact formulation is of most general importance and may be applied to many other contact problems of structural mechanics. The special case of an edge supported membrane structure, however, is a most illustrative case to demonstrate how this technique is embedded into CAD and the sliding contact can immediately be considered in the early stages of architectural design. As a consequence, the effect to the stresses and displacements can immediately be studied and controlled. The contribution briefly presents and verifies the newly proposed approach with some examples and demonstrates the applicability in different real-world problems.

Electric Field Analysis on Buffer Layer of HV XLPE Power Cable by Finite Element Method

In recent years, white defects in power cable buffer layer has been discovered many times around the world. It would be a hazard to electricity transmission if these defects are not detected and solved in time, finally resulting in a power outage. In this paper, the selection of a physics field and the building of a three-dimensional model on cable electric field simulation are mentioned and improved. The distribution of electric field was calculated with two factors: the gap between water-blocking tape and aluminum sheath, the conductivity of water-blocking tape. The results demonstrated that the existence of the gap increases the electric field intensity in the air layer. Increasing the conductivity of water-blocking tape is beneficial to reduce the electric field intensity. It was explained that white defects is closely related to the air discharge in buffer layer.

Modeling and optimization of gaseous helium (GHe) cooled high temperature superconducting (HTS) DC cables for high power density transmission

Superconducting cables are considered a viable technology to meet the increasing global demand of electricity transmission and distribution. This paper presents a transient mathematical model to predict the thermal response of a superconducting cable contained in a flexible cryostat. The model was conceived to be computationally fast so that system response according to variations of physical properties of the materials, and operating and design parameters could be assessed for optimization purposes. A volume element method (VEM) was utilized, which resulted in a system of ordinary differential equations with time as the independent variable. The model is also space dependent, through the establishment of a mesh with a known three-dimensional distribution of the volume elements in the computational domain. Pressure drop in the gas channels and the temperature gradient with respect to space in the flow direction were taken into account. The numerically calculated DC cable heat leak rate under different environmental conditions was initially adjusted and then experimentally validated by direct comparison to actual experimental data. The final part of the study consisted of using the experimentally validated model to perform the DC cable design and operating parameters optimization in order to obtain minimum heat leak rate and pumping power (or total consumed power). By adopting a fixed cable cross sectional area constraint (or total volume for a given length), an optimized helium channels geometry is also found that shows significant improvement in system performance in comparison to an existing system geometry. For example, for a GHe mass flow rate of 3.8 g s−1, the cryostat with the original geometry is shown to consume 20.5% more power than with the optimized geometry. As a result, it is reasonable to state that the combination of accuracy and low computational time allow for the future utilization of the model as a reliable tool for HTS DC cable & cryostat simulation, control, design and optimization purposes.

Numerical Simulation and Cold Test of a Compact 2G HTS Power Cable

Superconductinge power cables offer the advantages of lower loss, lighter weight, and smaller dimensions, in comparison with conventional cables. It is important to developed most compact cable with a small diameter to increase the transmission power density of a cable. Precise analysis should be used to provide optimal cable layout with uniform current distribution among layers. We have developed an electric circuit model of a cable, and two FEM models using a finite-element code ANSYS. The numerical simulations can provide detailed information about the current distribution inside the cable and the optimal parameters from the point of view of current distribution of the cable have been determined. On the base of the models, the compact 2G HTS cable model with three layers in the core and two layers in the shield has been produced and tested. The outer diameter of the cable was as small as ~20 mm that is less than previously 1G and 2G HTS power cables tested. The experiment with the model cable demonstrated that even rather small mistake in the diameter of a layer leads to considerable change of current distribution among layers. This phenomenon was analyzed with the simulation models developed. It was shown that change of a layer diameter as small as the thickness of one tape (~0.1 mm) led to the current distribution change observed. Calculated results qualitatively coincide with the experiments. In addition, ac losses at different frequencies have been measured to compare them with ac loss in previously tested cables with larger diameter.

Physical deformation configuration of a spatial clamped cable based on Kirchhoff rods

PurposeIn this study, a modeling method for a clamped deformable cable simulation based on Kirchhoff theory is proposed. This methodology can be used to describe the physical deformation configuration of any constrained flexible cable in a computer-aided design/manufacturing system. The modeling method, solution algorithm, simulation and experimental results are presented to prove the feasibility of the proposed methodology. The paper aims to discuss these issues.Design/methodology/approachFirst, Kirchhoff equations for deformable cables are proposed based on the nonlinear mechanics of thin elastic rods, and the general solution of the equations described by the Euler angles is given in the arc coordinate system. The parametric form solution of the Kirchhoff equations, which is easy to use, is then obtained in a cylindrical coordinate form based on Saint Venant’s theory. Finally, mathematical expressions that reflect the clamped cable configuration are given, and the deformable process is simulated based on an open source geometry kernel and is then tested by a 3D laser scanning technology.FindingsThe method presented in this paper can be adapted to any boundary condition for constrained cables as long as the external force and torque are known. The experimental results indicate that both the model and algorithm are efficient and accurate.Research limitations/implicationsA more comprehensive study must be executed for the physical simulation of more complicated constrained cables, such as the helical spring and asymmetric constraint. The influence of the material properties of the cable on the calculation efficiency must be considered in future analysis.Originality/valueThe semi-analytical algorithm of the cable simulation in cylindrical coordinates is a novel topic and is more accurate and efficient than the common numerical solution.

A finite element/quaternion/asymptotic numerical method for the 3D simulation of flexible cables

In this paper, a method for the quasi-static simulation of flexible cables assembly in the context of automotive industry is presented. The cables geometry and behavior encourage to employ a geometrically exact beam model. The 3D kinematics is then based on the position of the centerline and on the orientation of the cross-sections, which is here represented by rotational quaternions. Their algebraic nature leads to a polynomial form of equilibrium equations. The continuous equations obtained are then discretized by the finite element method and easily recast under quadratic form by introducing additional slave variables. The asymptotic numerical method, a powerful solver for systems of quadratic equations, is then employed for the continuation of the branches of solution. The originality of this paper stands in the combination of all these methods which leads to a fast and accurate tool for the assembly process of cables. This is proved by running several classical validation tests and an industry-like example.

Sliding cable modeling: An attempt at a unified formulation

Sliding cable structures are systems where cables experience a relative sliding motion with other structural elements. The variety of structural systems using sliding cables led to a great diversity and scattering of the modeling approaches. This paper presents original developments expanding and generalizing the existing works and proposes a multi-node sliding cable model accounting for friction, with a general dynamic formulation, an effective numerical implementation and applicability to various material behaviors. General sliding equations are formulated, along with the unstretched length conservation constraint. Closed-form expressions of the Newton–Raphson scheme are developed to solve the sliding equations analytically while enforcing the conservation constraint. The formulation and its implementation are validated against a theoretical dynamic sliding cable mechanism and simulation results agree perfectly with the analytical solutions. The model is used to perform a parametric study of a complex system of sliding cables under dynamic loading. These simulations highlight the influence of the investigated parameters and prove the robustness and versatility of the proposed model over the existing ones from the literature.

Assembly simulation of multi-branch cables

Cable assembly simulation is a key issue in the computer-aided design (CAD) of products with complex electrical components. In this study, an assembly simulation method is developed to simulate the assembly process of multi-branch cables. First, based on the Cosserat theory of elastic rods, a novel scheme is introduced to model the joints of multi-branch cables. The potential energy of joints is calculated by taking the topology and anatomical features into consideration. Various physical properties are considered. Various constraints, including connectors, collars, and handles are analyzed, based on which the initial conditions of assembly simulation are determined. The configuration of the cable is then calculated by minimizing its potential energy. To increase computational efficiency, GPU acceleration is introduced, which makes the simulation run at interactive rates even for a cable with resolution up to 1000 discrete points. Finally, the proposed algorithm is integrated into the commercial assembly simulation system, DELMIA. Several simulations were performed with our system. It was demonstrated that the proposed method is able to handle cables with complex topologies. In addition, the proposed method is about four times as efficient as a previous method, and it is able to generate realistic configurations of multi-branch cables at interactive rates. Thus, the proposed method is helpful in the assembly process planning of cables.

An innovative approach for numerical simulation of stress relaxation of structural cables

Relaxation test on cable with large diameter is usually difficult and money consuming due to its extremely large ultimate tensile strength. A simplified finite element modeling method for stress relaxation simulation of steel wire, semi-parallel wire strands and spiral strands was proposed. Simplified relationship between stress relaxation and creep of steel wires was derived and a simplified modeling method on spiral wire composition was proposed. The whole numerical approach incorporated the steel wire creep model and the simplified cable compositions to realize the simulation of stress relaxation behavior of structural cables. The effectiveness of proposed creep calibration and cable stress relaxation simulations were verified through relaxation test data of single-wires and 19-wire semi-parallel wire strands. The 19-wire, 37-wire, 61-wire, 91-wire and 127-wire semi-parallel wire strands and spiral strands at different initial stress levels were all simulated. Due to the spiral wire composition and corresponding gradient wire stress distribution under axial tension, relaxation rate of semi-parallel wire strands and spiral strands were all larger than that of single steel wire. Semi-parallel wire strands presented a decreasing relaxation rate with the increase of cable dimension. Spiral strands had larger relaxation rate than similar-sized semi-parallel wire strands, and present a slight relaxation increase trend with cable dimension. The proposed finite element modeling method can realize the stress relaxation analysis of large diameter structural cables, with only stress relaxation test data of single wires or small diameter cables.

Моделирование движения кабельной линии подводного аппарата в пакете Blender Game Engine

Моделирование движения кабельной линии подводного аппарата в пакете Blender Game Engine