Flexible Cables Research Articles

An Experimental Study on Vortex-Induced Vibration Suppression of a Long Flexible Catenary Cable by Using Vibration Dampers

In this paper, an experimental study is conducted to investigate the effectiveness of vibration dampers in suppressing vortex-induced vibration in a long, flexible catenary cable with a low mass ratio. The dampers, consisting of two small, symmetric, lightweight pipes clamped to the cable, are sparsely deployed along the cable to shape the vibration characteristics. The experimental results demonstrate that dampers significantly reduce the vibration amplitude by up to 60% and axial tension by up to 61% at high flow velocities, effectively suppressing the cable vibration in perpendicular flow. In addition, it is observed that the in-line and cross-flow vibration frequencies are approximately equal when the dampers are applied. This behavior contrasts with the conventional undamped catenary cable, where the in-line vibration frequencies are double those of the cross-flow frequencies.

Experimental study on the critical current in highly flexible REBCO cables under copper tube compaction

The Institute of Plasma Physics Chinese Academy of Sciences (ASIPP) is developing the high-current REBCO cable-in-conduit conductor (CICC) for use in the Central Solenoid (CS) coil of the next generation nuclear fusion device. The aim is to develop a CICC comprising six REBCO sub-cables to satisfy the requirements of operation with a current of around 46 kA and a peak field of up to 20 T. Sub-cables, as crucial components within CICCs, play a pivotal role in ensuring the mechanical support strength and current-carrying stability of the entire CS coil system. Therefore, a process was developed in this paper for the first time to make a sub-cable that meets the requirements by inserting the Highly Flexible REBCO Cable (HFRC) cable into a copper tube and compacting it. Meanwhile, the feasibility and reliability of this process were evaluated and optimized using experimental methods at 77 K and self-field. The result indicated that sub-cables without copper tape protection experienced a 25.42% degradation in critical current (IC). In contrast, when at least one protective layer of copper tape was used as a protective buffer between the HFRC cable and the inner wall of the copper tube, the IC remained stable within a 1% error margin after compaction. These findings demonstrate the feasibility of this sub-cable preparation process. Meanwhile, this compaction method provides a solid process foundation for the development of full-size conductors in future magnet applications.

Flexible and Extensible Ribbon-Cable Interconnects for Implantable Electrical Neural Interfaces.

The design and characterization of thin-film ribbon cables as electrical interconnects for implanted neural stimulation and recording devices are reported. Our goal is to develop flexible and extensible ribbon cables that integrate with thin-film, cortical penetrating microelectrode arrays (MEAs). Amorphous silicon carbide (a-SiC) and polyimide were employed as the structural elements of the ribbon cables and multilayer titanium/gold thin films as electrical traces. Using photolithography and thin-film processing, ribbon cables with linear and serpentine electrical traces were investigated. A cable design with an open lattice geometry was also investigated as a means of achieving high levels of extensibility while preserving the electrical function of the cables. Multichannel ribbon cables were fabricated with 50 mm lengths and metallization trace widths of 2-12 μm. The ribbon cables tolerate flexural bending to a radius of 50 μm with no change in trace impedance but tolerate less than 5% tensile elongation without trace failure. Ribbon cables with a lattice structure exhibit 300% elongation without failure. The high elongation tolerance is attributed to a lattice design that results in an out-of-plane displacement that avoids fracture or plastic deformation. Extensible ribbon cables underwent up to 50,000 tensile elongation cycles to 45% extension without failure. An electrical interconnect process using through-holes in the distal gold bond pads of the ribbon cables was used to connect to an a-SiC-based MEA. The electrical connection was created by stenciling a conductive epoxy into the through-holes, bridging metallization between the traces, and MEA. The interconnect was tested using a ribbon cable connected to an a-SiC MEA implanted acutely in rat cortex and used to record neuronal activity. These highly flexible and extensible ribbon cables are expected to accommodate large extensions and facilitate cable routing during surgical implantation. They may also reduce tethering forces on implanted electrode arrays, potentially improving chronic neural recording performance.

Dynamics Modeling and Motion Evaluation of a Near-Ground Tethered Balloon Cable System under Severe Wind Environments

Weather survival poses a significant challenge for the utilization of tethered balloons. The dynamic modeling of tethered balloon systems presents challenges due to the flexible nature of the cables and the intricate nature of gust forces. The present study introduces a new approach for modeling near-ground tethered balloon systems, which enables the analysis of their dynamic responses and performance evaluation under complex boundary conditions. First, finite cylindrical rigid bodies that are joined together by bushing forces to describe the dynamics of the tethered cable. The properties of the flexible cables under severe bending and translation can be illustrated by the dynamics model. Second, a three-dimensional dynamics model based on the multibody dynamics theory is created to deal with the interaction of the tethered balloon system and flexible cables. The dynamic responses of the tethered balloon system under challenging operating conditions are investigated, focusing on the number of cable segments and the place and direction of gust wind impacts. This model allows for precise assessment and optimization of the system’s overall performance to improve weather resistance. The results show that compared to computational fluid dynamics (CFDs) methods, the multibody system dynamics-based balloon model improved the solution time by 80%, with a pitch angle deviation of only 0.0016°. Moreover, the bushing model effectively reduced cable force and enabled accurate reflection of the system’s motion characteristics.

Consensus Tracking and Vibration Control for Multiple Overhead Cranes With Flexible Cables Under Time-Varying Actuator Faults

Consensus Tracking and Vibration Control for Multiple Overhead Cranes With Flexible Cables Under Time-Varying Actuator Faults

Research and Application of Online Electromagnetic Heating System with Internal Penetration in Oil Pipeline at Well Site

Abstract In response to the current situation of heating crude oil in the oil pipeline of Changqing Oilfield, most of the well sites have no associated gas, gas heating furnaces have been discontinued, and coal-fired heating furnaces pollute the environment. A study was conducted on the online through type heating system for the oil pipeline in the well site, with a focus on the composition and function of the digital heating system for the through type oil pipeline in the well site. The through type online heating system for the oil pipeline in the well site is mainly composed of a variable frequency electromagnetic controller The online controller and internal heating cable are composed of three parts. The oil pipeline generates heat by itself, while preventing the crystallization of paraffin and scale in the oil pipeline under the action of alternating electromagnetic fields, which is not easy to form wax. In 2023, on-site application was carried out on two oil pipelines in the Tongzhai operation area of the Third Oil Production Plant in Changqing Oilfield, replacing the existing gas heating furnaces and coal-fired heating furnaces to heat and transport crude oil in the oil pipelines. It does not generate heat itself and has a long service life. Due to the high thermal efficiency of the heat source coming from the inside of the oil pipeline, the buried pipeline renovation can be installed without breaking the soil. The flexible internal cable reduces the difficulty of construction and is safe and environmentally friendly, At the same time, it can remotely monitor the temperature of crude oil in the oil pipeline and the wellhead backpressure online.

CORC® wires allowing bending to 20 mm radius with 97.5% retention in critical current and having an engineering current density of 530 A mm−2 at 20 T

Abstract Low-inductance, high-field insert solenoid magnets and 20 T dipole magnets for particle accelerators require flexible cables, wound from high-temperature superconductors (HTS) such as RE-Ba2Cu3O7-δ (REBCO) coated conductors, that allow bending to a 20 mm radius without significant degradation in performance. They require an operating current of at least 5 kA and a high engineering current density (Je) exceeding 500 A/mm2 at 20 T. HTS cable technologies that target such demanding magnet applications so far haven’t been able to meet the combination of these requirements.
Here we present the development of the next generation of Conductor on Round Core (CORC®) wires that improves their bending flexibility by factor of more than 2 compared to previous generation CORC® wires. CORC® wires now allow for a bending radius of 20 mm with only 2 – 3 % performance degradation. They allow bending to a radius of 15 mm with a performance retention of 83.5 %. The performance of 30-tape CORC® wires wound from 2 mm wide REBCO tapes from SuperPower Inc, SuperOx and Shanghai Superconductor Technologies was measured at magnetic fields up to 12 T. The overall performance at high magnetic fields of the next generation of CORC® wires improved by a factor of 1.5 – 1.8, depending on the REBCO tape manufacturer. CORC® wires wound from production REBCO tapes achieved a new record Je of 751 A/mm2 at a current of 8.3 kA at 12 T, and a Je of 530 A/mm2 at a current of 5.8 kA when extrapolated to 20 T. 

Experimental study of vortex-induced vibration of stay cables installed with two types of perforated shroud light devices

To address both illumination issues and the common vortex-induced vibration (VIV) of bridge cables, a perforated shroud light device is proposed. The effect of the different porosities (20%, 35%, 42%, and 55%) on VIV of the rigid segmented shroud cable models is studied first by wind tunnel tests. It reveals that shrouds with porosities of 20% and 35% could reduce the VIV amplitude of the smooth cables by 26% and 46%, respectively. However, shrouds with porosities of 42% and 55% tend to increase the complexity and risk associated with VIV. Vibration measurements on flexible should cable with 20% porosity were conducted for both vertical and inclined models with an inclination of 35° and yaw angles of 0°, 30° and 60°. Shrouds with a porosity of 20% exhibit similar effects on vertical flexible cables as on horizontal rigid cables, in both cases mitigating VIV. The impact on the inclined flexible cables depends on the yaw angle. At the yaw angle of 0°, the shroud effectively mitigates VIV in flexible cables. However, at yaw angles of 30° and 60°, the same porosity level shroud exacerbates the risk of VIV in the inclined flexible cable. This may be due to the enhanced wind velocity along the cable axial direction and decreased penetrating flow rate through the shroud as the wind yaw angle increases. Overall, it was found that a shroud with a porosity of 20%–35% performed the best and was recommended for applications on cables with no inclination and inclined cable at yaw angle β = 0°.

Load torque estimation for cable failure detection in cable-driven parallel robots: a machine learning approach

AbstractThis paper proposes a method for cable failure detection in cable-driven parallel robots (CDPRs) with arbitrary architecture, which is based on the estimates of the motor load torques, together with machine learning algorithms. By just exploiting the dynamic model of each actuator in the conditions of no load, an open-loop load torque observer is designed for each motor to estimate the presence of a load coupled through a cable. Since such a load instantaneously goes to zero for the motor with a broken cable, a simple but effective and robust signature of failure can be inferred to provide reliable detection even in the case of various model mismatches. Additionally, the load torque observer is not computationally demanding since just motor measurements are required, thus avoiding any direct measurement (and a dynamic model as well) on the end-effector. The detection of a failure is made through supervised classification algorithms based on artificial intelligence. The training of the machine learning algorithm is based on a “hybrid” approach: the dataset includes several failure cases, which are numerically generated through a system digital twin developed through the multibody system theory, together with measurements of the real system in nonfailing conditions. Different classification algorithms are considered, together with different sets of input variables to be fed to the classifier. Four numerical examples are proposed by showing the method capability in handling both fully actuated and redundantly actuated CDPRs under cable failure, both rigid and flexible cables, and also evaluating the response in the presence of cable slackness.

Controlling a Virtual Structure Involving a UAV and a UGV for Warehouse Inventory

A control system based on the control paradigm of virtual structure is here proposed for a multi-robot system involving a quadrotor and a ground vehicle, operating in an automated warehouse. The ground robot can either provide extra power to the quadrotor, thus increasing its autonomy, or receive data from it. Therefore, the quadrotor is tethered to the ground robot through flexible cables, thus justifying the adoption of the virtual structure control paradigm, which allows controlling the two vehicles simultaneously. The control approach adopted aims at guiding the virtual vertical line joining the two robots to allow the quadrotor to produce an inventory of goods in an automated warehouse. Therefore, the two robots should visit a sequence of known positions, in front of cabinets of vertically arranged shelves. In each of them the quadrotor should read QR codes, bar-codes or RFID cards corresponding to the stored boxes, to produce the inventory. Therefore, the control objective, the focus of this paper, is to keep the shape of the virtual vertical line linking the two robots while moving. However, when an obstacle appears in the route, such as a box or other robot in the floor or another aerial robot, the formation changes its shape accordingly, to avoid the obstacle. An experiment in lab scale, mimicking a real situation, is run, whose results allow claiming that the proposed system is an effective solution for the problem of controlling a multi-robot system to produce an inventory in an automated warehouse.

Solution of geometrico-static problems and motion experiments for a suspended under-constrained parallel mechanism driven by two flexible cables

Solution of geometrico-static problems and motion experiments for a suspended under-constrained parallel mechanism driven by two flexible cables

Dynamic modeling of cable deployment/retrieval based on ALE-ANCF and adaptive step-size integrator

The towing vehicle must maintain a stable distance from the seafloor to ensure the accuracy and safety of deep-towed seismic systems. However, due to equipment limitations, controlling the towing depth is achievable solely by adjusting the length of the towing cable. In this study, an Absolute Nodal Coordinate Formulation (ANCF) with Arbitrary Lagrange-Euler (ALE)description is employed to model variable-length flexible towing cables. The inertial and elastic force formulas for ALE-ANCF, along with their corresponding Jacobian matrices, are derived in detail, and their coefficient matrices are precomputed to avoid Gaussian integration. The proposed adaptive step-size strategy enhances computational efficiency. Detailed investigation into the impact of cable deployment/retrieval on towing depth is conducted, revealing an almost linear relationship between length change and towing depth. In Addition, a proportional, integral, derivative (PID) controller with compensation is proposed for efficiently tracking the target depth and alleviating the perturbations from the mothership, illustrating the feasibility of PID control. These findings hold practical significance for enhancing the operational safety and efficiency of deep-towed seismic systems.

Dynamic modeling of a sliding ring on an elastic rod with incremental potential formulation

Abstract Mechanical interactions between rigid rings and flexible cables find broad application in both daily life (hanging clothes) and engineering system (closing a tether-net). A reduced-order method for the dynamic analysis of sliding rings on a deformable one-dimensional (1D) rod-like object is proposed. In contrast to the conventional approach of discretising joint rings into multiple nodes and edges for contact detection and numerical simulation, a single point is used to reduce the order of the model. To ensure that the sliding ring and flexible rod do not deviate from their desired positions, a new barrier function is formulated using the incremental potential theory. Subsequently, the interaction between tangent frictional forces is obtained through a delayed dissipative approach. The proposed barrier functional and the associated frictional functional are C2 continuous, hence the nonlinear elastodynamic system can be solved variationally by an implicit time-stepping scheme. The numerical framework is initially applied to simple examples where the analytical solutions are available for validation. Then, multiple complex practical engineering examples are considered to showcase the effectiveness of the proposed method. The simplified ring-to-rod interaction model has the capacity to enhance the realism of visual effects in image animations, while simultaneously facilitating the optimisation of designs for space debris removal systems.

Equivalence of flexible stripline and coaxial cables for superconducting qubit control and readout pulses

We report a comparative study on microwave control lines for a transmon qubit using (i) flexible stripline transmission lines and (ii) semi-rigid coaxial cables. During each experiment, we performed repeated measurements of the energy relaxation and coherence times of a transmon qubit using one of the wiring configurations. Each measurement run spanned 70–250 h of the measurement time, and four separate cooldowns were performed so that each configuration could be tested twice. From these datasets, we observe that changing the microwave control lines from coaxial cables to flexible stripline transmission lines does not have a measurable effect on coherence compared to thermal cycling the system or random coherence fluctuations. Our results open up the possibility of large-scale integration of qubit control lines with integrated component with planar layouts on flexible substrate.

A high‐power and high‐efficiency low‐profile aperture converter array

AbstractFor a phased‐array antenna system, position mismatches in spacing distances between source's output and antenna arrays’ input ports are common. At present, flexible radiofrequency cables are always utilized to electrically connect those two parts, which will result in the reduced integration. To tackle this problem, a low‐profile aperture converter array (ACA) is first proposed, which is applied between a microwave source and antenna arrays. Each stripline‐structured channel of the ACA is composed of the signal lines with different routing shapes to achieve nearly the same phase shift. In this study, a high‐power and high‐efficiency 16‐channel ACA is designed, fabricated and measured at X‐band. Experimental results show that it meets the requirement of 5‐kW pulse wave input, and the power transfer efficiency of each channel is more than 93.8%. Furthermore, its profile is only 0.42 at 9 GHz, which is favorable to transforming the integration of the whole system.

A study on vortex-induced vibration of a long flexible catenary cable in perpendicular flow

In this paper, a numerical model based on Euler-Bernoulli beam theory and a single van der Pol wake oscillator model is proposed to study the vortex-induced vibration of a long flexible catenary cable with a low mass ratio. The wake model uses only one oscillator to describe the in-line and cross-flow vibration with consideration of their nonlinear coupling. An experiment on a flexible cable model in perpendicular flow is carried out to validate the proposed numerical model. Numerical results and experimental measurements are compared on the vortex-induced vibration responses including the maximum amplitude, axial tension, and vibration frequency. A sensitivity analysis of the parameters used in the numerical model has been carried out. Numerical simulations by the proposed numerical model with properly selected parameters have demonstrated that the vibration frequency and the axial tension can be well predicted, and the variation of the vibration amplitudes can also be properly captured. The lock-in phenomena and the axial tension variation of the long flexible catenary cable in perpendicular flow have been carefully studied both numerically and experimentally.

Enabling magnetic pulse welding for dissimilar tubular arrester cable joints

Climate change exacerbates the need for resource-efficient and cost-effective production processes across manifold industries, including the field of electrical connections. This specific field is characterized by a conflict of objectives, i.e., weight reductions while maintaining joint strength and electrical conductivity. From a material point of view, the use of aluminum as a conductor material is suitable for this application, as it is lighter than copper, a classical conductor material. Electrical conductors are often used in the form of flexible cables, so-called stranded wires. This type of conductor as well as the fact that the sole use of aluminum in electrical systems is not feasible, e.g., because the predetermined connection terminals of power electronic components are made of copper, creates a substantial demand for dissimilar aluminum-copper cable arrester joints. However, traditional fusion-based welding processes have proved incapable of reliably producing these dissimilar aluminum-copper joints because of thermophysical effects and chemical incompatibilities, the latter eventually leading to the formation of intermetallic phases. These phases adversely affect the quality of the joint in terms of both mechanical and electrical performance. Yet, magnetic pulse welding, a pressure welding process, is ideally suited for producing dissimilar metal joints on the basis of a low energy input during the welding process. Consequently, the formation of intermetallic phases is restrained. However, magnetic pulse welding has not been sufficiently investigated for the reliable contacting of stranded cables to tubular arresters. As a result, this paper focuses on the fabrication of tubular stranded cable arrester joints using magnetic pulse welding. To shed light on possible material combinations, aluminum-to-aluminum and copper-to-copper joints as well as their dissimilar counterparts are welded. Subsequently, the joints are characterized with regard to their microstructure and quasi-static material strength. Electrical characterization comprises the four-wire Kelvin measurement method to evaluate the resistance of the electrical joints. The results demonstrate that magnetic pulse welding is ideally suited to join the aforementioned material combination and joint configuration due to its process characteristics eventually leading to material continuity. As a result, the stranded wires are welded to the tubular arresters rather than crimped. Consequently, a comparative analysis of the joint properties with those of the joining partners shows that the measured electrical resistances and mechanical tensile forces may be considered very good.

Online Self-Calibration of Cable-Driven Parallel Robots Using Covariance-Based Data Quality Assessment Metrics

Abstract This paper presents an algorithm to perform self-calibration of cable-driven parallel robots (CDPRs), where the CDPR's end-effector pose is estimated in conjunction with the calibration of biases in the CDPR's measurements. Two new metrics, known as the position dilution of precision (PDOP) and orientation dilution of precision (ODOP) are introduced as a means to quantify the quality of data collected with regards to self-calibration. These metrics are based on a covariance matrix that is computed online as part of the proposed self-calibration algorithm, which results in the PDOP and ODOP directly corresponding to the standard deviation of the position and orientation errors, respectively. These metrics are used to intuitively select which data points contribute to improved calibration, resulting in a computationally-efficient algorithm requiring few data points to maintain accurate calibration. Additionally, the PDOP and ODOP provide a means to assess when sufficient calibration data has been collected. Numerical results involving an inverse kinematic simulation with rigid cables and a dynamic simulation with flexible cables indicate that the proposed algorithm is capable of performing self-calibration in a computationally-efficient manner. Moreover, the simulation results indicate that the proposed PDOP and ODOP metrics result in smaller position and orientation errors when used to prune the data set compared to the observability indices found in the literature. Accuracy of the proposed algorithm is also confirmed through experiments when compared to ground-truth pose data.

Improved Flexible Coaxial Ribbon Cable for High-Density Superconducting Arrays

Improved Flexible Coaxial Ribbon Cable for High-Density Superconducting Arrays

A 6-around-1 cable using high-temperature superconducting STAR ® wires for magnet applications

To generate a dipole field above 20 T, we need high-temperature superconductors, including REBa2Cu3O 7−x (RE = rare earth, rebco) coated conductors. However, the optimal architecture of a high-current flexible rebco cable is not yet settled for high-field magnet applications. Here we report a 6-around-1 cable concept based on the high-temperature superconducting star ® wires. We made two cable samples. One had a single star ® wire and the other had six star ® wires. The cable with six star ® wires was 1.5 m long. It had a diameter of 5.7 mm and a pitch length of 52 mm. The critical current of the cable before bending was 1448 A at 77 K, retaining at least 77% of the total critical current from individual star ® wires. The cable had a low n value around 4.5. At a bend radius of 30 mm, the critical current and n value remained the same as before bending. The total resistance of electrical terminations was 61 nΩ at 77 K. The flexible and transposed 6-around-1 star ® cable can provide another route toward practical rebco conductors for high-field accelerator and fusion magnet applications.