Tape Wound Research Articles

Finite-Element Analysis of the Strain Distribution Due to Bending in a REBCO Coated Conductor for Canted Cosine Theta Dipole Magnet Applications

High-current cables using REBCO tapes can be used to develop high-field dipole magnets. However, the strain accumulated during cable fabrication and coil winding may reduce the critical current of the conductor. Therefore, it is important to properly consider the strain when designing high-field magnets. In this paper, we used structural finite-element analysis (FEA) to predict the strain experienced by a REBCO tape during bending in configurations relevant to the fabrication of high-field accelerator magnets, in particular, the mechanical strain generated during cable fabrication and winding in a canted-cos θ dipole configuration. We considered two different cable options: (A) Flat tape that lay in the mandrel channel and (B) a REBCO tape helically wound around a circular copper core, the typical configuration of the conductor in round core cable (CORC). Strain accumulated during tape winding is studied for different core diameters and winding tilt angles. FEA longitudinal strain results were compared with the simulations for configuration A, where higher strain was observed experimentally. Configuration B was verified indirectly by comparing experimentally measured Ic with the one predicted (based on the longitudinal strain) as a function of the bending diameter. Good agreement was found up to a bending diameter of 30 mm. The presented results will help to understand the impact of bending on REBCO tapes and CORC wires to develop high-field magnets.

INVESTIGATION OF EXPLOSION SAFETY OF DC POLYMER SURGE ARRESTERS 3.3 KV FOR TRACTION NETWORK OF RAILWAY TRANSPORT

In the testing laboratories of Ukraine, there is no high-voltage equipment of the necessary energy for testing surge arresters for explosion safety, which does not allow to estimate this indicator at the stage of development of prototypes. In view of this test, the polymer prototypes of the DC surge arresters in polymer case (SAp) 3.3 kV were tested under the operating conditions of the equipment of the operating substation with short-circuit currents of 8.3 kA and a current time of 0.02 seconds, close to the recommended by Standard of IEC 60099-4:2014 values. 8 samples of surge arresters were tested. A sample of the surge arrester was mounted on one of the metal supports at a height of 5.5 m located in the substation and connected to the 3.3 kV traction substation buses through disconnectors and a high-speed switch. After the short-circuit breaker was closed through a column with a pre-punched or shunted copper wire varistor, a short-circuit current flowed to form an electric arc inside the arrester samples. During the tests video samples were recorded using a video recorder installed in close proximity to the test sample. The frame of the SAp samples in which the varistors were enclosed was performed either by winding the fiberglass tape on a varistor column, or from rods arranged in the form of a squirrel cage, or in the form of a fiberglass tube with a hole for gas ejection during a short circuit inside the SAp. The destruction of the hull occurred without scattering of the fragments in seven cases from the eight samples tested. In seven samples, a local rupture of the silicone shell occurred in the varistor zone, a gas ejection and an arc discharge occurred through this gap. The exception was sample No. 2, made by a continuous winding of a glass-banding tape on a varistor column, in which, during the explosion, the upper electrode exploded with the simultaneous expansion of fragments of the varistor in a radius of 3-5 m. Due to the white smoke accompanying the explosion, it was not possible to fix on the frame whether the arc output from the case to the outside, despite the fact that on the next frame (in 33 ms.) the arc was no longer fixed. In the tests of eight of the presented designs, none of them ignited the hull. If the tests were carried out on the surge arresters assembled with pre-punched varistors (electrothermal breakdown), the varistors during the tests split, remaining inside the frame. From the action of the arc in the contact zone of the aluminum electrodes with varistors, a deep burn-out of the electrodes was observed, in some cases, the burnup was up to 7 mm deep and up to 8 mm wide. If the varistors were shunted by a copper wire, they remained intact. If the varistors were shunted by a copper wire, they remained intact und melting and burning out a part of the aluminum electrodes in the area of connection with the copper wire were smaller sizes. The samples showed a completely satisfactory ability to withstand large pulse currents without dispersing dangerous fragments for personnel and surrounding equipment. However, polymer designs, the frame of which is made by continuous winding, require reinforcement of the connection zone of the carcass with electrodes to exclude the break-out of electrodes during the accumulation of gases during a short circuit inside the shell of the SAp. For such designs, an additional test for mechanical strength in the longitudinal direction with a predetermined norm is required in the acceptance test program.

Effect of monotonic and cyclic axial tensile stress on the performance of superconducting CORC® wires

High-current superconducting CORC® wires, wound from RE-Ba2Cu3O7−δ (REBCO) coated conductors, are being developed for use in high-field magnets that would allow operation at magnetic fields exceeding 20 T. The combination of high engineering current densities and high magnetic fields results in large Lorentz forces acting on the CORC® wire that could cause irreversible degradation to its performance. The effect of axial tensile stress on the critical current of CORC® wires containing annealed solid copper formers has been measured in liquid nitrogen to determine the irreversible stress limit at which irreversible degradation occurs. The results show no significant change in critical current before the irreversible stress limit is reached, after which the critical current decreases irreversibly with applied stress. The irreversible stress limit as high as 177 MPa depends on the yield strength of the former, the number of superconducting tapes wound into the CORC® wire and the angle at which the tapes are wound. Although the irreversible stress limit of CORC® wires is lower than a rudimentary rule of mixtures estimation would suggest, the irreversible strain limit, as high as 0.85%, exceeds that of single REBCO tapes. Both effects are likely the result of the helical fashion in which the REBCO tapes are wound into CORC® wires. The performance of CORC® wires was also measured as a function of axial tensile stress fatigue cycling in liquid nitrogen. No significant performance degradation was measured up to 100 000 cycles as long as the peak stress remained below the irreversible stress limit. Only once the peak stress was increased significantly above the irreversible stress limit would the critical current suddenly decrease with stress cycles. The results indicate that CORC® wires have matured into extremely robust high-current magnet conductors capable of withstanding high levels of axial tensile stress and strain. The irreversible stress limit of CORC® wires could be increased further by using stronger formers and winding the REBCO tapes at comparable angles, while the irreversible strain limit could potentially be increased by tailoring the winding angle of the REBCO tapes, making CORC® wires one of the strongest and most elastic high-current superconducting magnet conductors available.

Development and testing of a 1 G based high temperature superconducting (HTS) double pancake coil for HTS synchronous machines

High Temperature Superconducting (HTS) synchronous machines are highly efficient, compact, lighter, low noise, high output power to weight ratio and better dynamic response machines compared to conventional copper conductor based machines. HTS synchronous machines are used worldwide for various strategic and critical industrial applications, because of the above mentioned advantages. Successful development of HTS synchronous machine requires HTS, electrical, mechanical, cryogenic and vacuum technologies. The major components of a HTS rotor and copper winding stator topology synchronous machine are air gap copper winding stator, HTS rotor, excitation system, cryogenic cooling and vacuum systems. HTS rotor consists of HTS tape wound pole coils, which generate DC magnetic field when DC current passes through them. There will be no joule heat in the HTS pole coils due to superconductivity. Each pole coil consists of few numbers of field coils (in the form of double pancake coils) which are stacked to form a pole. One of the main technical challenges for manufacturing HTS rotor is development of HTS field coil. The development of a HTS field coil involves the selection of HTS tape, winding technique, handling of the HTS tapes while winding and testing of the HTS coil at cryogenic temperatures of 77 K and 35 K. In the present work, a HTS racetrack double pancake coil using 1 G HTS tapes was fabricated and tested. The details of design, development and cryogenic testing of 1 G HTS tapes wound double pancake coil are presented in this paper.

Temperature analysis for the laser-assisted tape winding process of multi-layered composite pipes

Tubular structures of fiber-reinforced polymer composites are utilized in various applications such as risers in the oil and gas industry and hydrogen pressure vessels in the automotive sector. The laser-assisted tape winding process presents an automated and efficient solution for the manufacturing of these structures out of thermoplastic composites. However, in order to guarantee reliable and high-quality process results, the temperature distribution within the laminate governing the consolidation between successively wound layers has to be understood and taken into account for process design. In an experimental setup, thermocouples were embedded between the layers in multiple spots along the perimeter during the manufacturing of pipe samples with five layers wound on a pure thermoplastic liner. This enabled capturing the through-thickness temperature distribution at different transversal locations. In addition to the temperature data recorded by the thermocouples, a stationary infrared thermographic camera focused on the laser-heated area was mounted on the tape winding head. The temperature data points of both sources were contrasted to evaluate how the through-thickness temperature distribution reflects the temperature input on the surface. Furthermore, the experimentally determined temperature distribution was compared with the results of a numerical process model, drawing conclusions with regard to the modelling and control of the multi-variable process.

A retrospective comparison of 3M™ Micropore™ with other common dressings in cosmetic breast surgery

Surgical site infection has considerable cost implications for healthcare providers. Evidence suggests that the use of Micropore™ tape as a dressing for surgical incisions may be associated with reduced/comparable rates of infection in surgical wounds. 3M™ Micropore™ tape is significantly cheaper than conventional wound dressings. The purpose of this study was to compare differences in the rate of wound healing problems including superficial incisional surgical site infection (SSI) and wound healing problems following cosmetic breast procedures between Micropore™ tape and other common wound dressings. A clinical database was utilised to identify all patients undergoing elective breast surgery at a UK private cosmetic surgery group between May and November 2017. The patients were divided into 2 groups: those whose wounds were dressed with 3M™ Micropore™ tape post-operatively and those dressed with other common wound dressings. Data was analysed to assess the prevalence of post-operative wound healing problems (superficial incisional surgical site infection and delayed wound healing) in each group. 1216 patients were identified in our database, 659 patients receiving Micropore™ and 557 patients receiving conventional wound dressings. The overall prevalence of wound healing problems in the Micropore™ tape and conventional wound dressing group were 12% and 10% respectively, with no statistical difference (p = 0.3913). There was no statistical significance between the use of antibiotics and prevalence of wound healing problems in either group. The results of our study suggest that there is no difference between the use of Micropore™ tape and other conventional wound dressings in the prevalence of post-operative wound healing problems in cosmetic breast surgery. Our findings support the routine use of Micropore™ tape in post-operative dressing for clean, non-contaminated, directly closed, elective surgical wounds. We suggest a larger scale, prospective, randomized study should be conducted to confirm these initial findings.

Development of methods to control quality of the structure of cross-wound packages

The process of winding is one of the principal processes in the textile industry. Quality of the formed packages largely defines the quality of the finished product in the textile industry, as well as labor productivity and equipment performance. Therefore, attention to analysis of processes of package formation, construction of new promising methods and designs of winding mechanisms, has been growing for many decades. We address issues related to the analysis of control methods over the structure of the cross-wound winding used in spinning production. The structure of winding is understood in the present work as the mutual arrangement of threads when they are laid on the surface of the package. Thus, the parameters of the structure include such quantities as a turn lifting angle, a distance between the points of turn reversal, a step in turns, etc. It is known that the mutual arrangement of turns on the winding body when packages are frictionally driven is not homogeneous. Under certain ratios between rotation speed of the bobbin and motion frequency of the thread guide, the threads are laid on the same place. In this case, the so-called braid formations are observed. If motion frequencies of the bobbin and the thread guide differ slightly from the multiple ones, turns are placed close to each other, in this case, a tape winding is formed. The braid winding is accompanied by a number of phenomena, which negatively affect quality of the formed packages. In this case, the shear and displacement parameters are determined based on empirical data. To substantiate the approach to choosing the technological parameters for such mechanisms, we performed a theoretical analysis of the process of braid structures formation in terms of the force interactions between threads. To make such a choice, it is necessary to have an instrumental procedure for quantifying the winding structure parameters, which is why we have in detail investigated methods for their registration.

Effect of Mechanical Loading on Coated Conductor Tapes Due to Winding Onto Round Cables

The influences of stresses/strains on critical current, I c in REBCO high-temperature superconducting (HTS) tapes wound onto a round cable were investigated. In the first step, the HTS tapes were helically wound on copper tubes with various diameters in the range of 2.95-8 mm. Considerably better results were achieved in case the superconducting layer was positioned during the winding at the inner side of the helix. The cables with tape wound on the tube with a diameter of 6.35 mm were subjected to bending tests with various bending radii in range from 21 to 60.5 mm. The I c degradation as a function of both the tube diameter and bending radius has been assessed from a current- voltage curve, from which the critical current was determined. The I, degradation in all samples was confirmed by microstructural investigation of an HTS layer by scanning electron microscopy.

Experimental and Numerical Investigation of Shielding Performance of Superconducting Magnetic Shields Using Coated Conductor Tapes

This study investigated the magnetic shielding performance of various configurations of superconducting cylinders based on high temperature superconducting Coated Conductor (CC) tapes. We applied ac magnetic fields with various frequencies and amplitudes to superconducting cylinders with CC tapes. The magnetic shielding performances of the cylinders with a variety of layer number and length of the cylinder were compared. We also performed the numerical simulations, and got the same tendency as the experimental results. We clarified that the shielding factor lineally increases with the layer number of the CC tape. More than five layers of the CC tape wound with the same orientation and angle to cover the gaps of an inner layer achieves 98% attenuation of the magnetic field. However, the simulation and experimental results show that shielding factor is not greatly improved by increasing the length of the cylinder due to the magnetic field penetration from the gaps between each winding of the CC tape. This study demonstrates a good possibility and also the limitation to use CC tapes for the magnetic shielding.

Multi-Response Parameter Interval Sensitivity and Optimization for the Composite Tape Winding Process.

The composite tape winding process, which utilizes a tape winding machine and prepreg tapes, provides a promising way to improve the quality of composite products. Nevertheless, the process parameters of composite tape winding have crucial effects on the tensile strength and void content, which are closely related to the performances of the winding products. In this article, two different object values of winding products, including mechanical performance (tensile strength) and a physical property (void content), were respectively calculated. Thereafter, the paper presents an integrated methodology by combining multi-parameter relative sensitivity analysis and single-parameter sensitivity analysis to obtain the optimal intervals of the composite tape winding process. First, the global multi-parameter sensitivity analysis method was applied to investigate the sensitivity of each parameter in the tape winding processing. Then, the local single-parameter sensitivity analysis method was employed to calculate the sensitivity of a single parameter within the corresponding range. Finally, the stability and instability ranges of each parameter were distinguished. Meanwhile, the authors optimized the process parameter ranges and provided comprehensive optimized intervals of the winding parameters. The verification test validated that the optimized intervals of the process parameters were reliable and stable for winding products manufacturing.

New analytical and numerical optical model for the laser assisted tape winding process

New analytical and numerical optical models are proposed for the laser assisted tape winding (LATW) of thermoplastic composites. The irradiation and reflection of the laser beam directly influence the heat flux and temperature distribution during the consolidation, hence the laser optics must be described and understood well for improved bonding quality. For the first time, a two-dimensional (2D) analytical solution is derived for the laser light distribution and reflection by combining the principle of energy conversation with unpolarized Fresnel equations. In the more comprehensive numerical model, a 3D ray tracing approach is incorporated in which a novel non-specular reflection model is developed predicting the anisotropic reflective behaviour of the composite. Heat flux distributions for the substrate and incoming tape are calculated. The analytical and numerical model results are shown to correspond. The non-specular and scattering reflection yields in a larger illuminated area with lower intensity for substrate and tape.

Comparison of Wound Tape and Suture Wounds on Traumatic Wounds' Scar

Background:Several methods have been used in wound closure for traumatic wounds, but it is not clear that which of these methods has more safety and efficacy. This study aimed to compare scar width due to standard and current treatments in wound repair by suturing and method of wound restoration using wound tape in patients with traumatic ulcers.Materials and Methods:This randomized clinical trial was done in ninety patients with wounds in the facial area. They were divided randomly into two groups of 45. The wounds in the first group were sutured, and wound tapes were used to wound closure in the second group. After 2 months, length and width of scar and results of life-size photography were recorded in a list, especially prepared for this purpose.Results:The mean age of the patients was 22.7 ± 12.9 years with 46 males (56.1%) and 36 females (43.9%). After 2 months, scars width in suture wound group was 2.9 mm and in wound tape group was 2.5 mm, with no statistically significant difference (P = 0.07). In patients with wound length of >20 mm, scars width was similar between groups and no significant differences was noted (P = 0.27), but in patients with wound length of <20 mm, scars width in wound tape group was significantly less than suture wound group (1.7 vs. 2.5 mm, respectively, P = 0.01). Wound complications were not significantly different between the two groups.Conclusion:Findings revealed that scar formation in wounds lower than 20 mm treated using wound tape was lower than suture, but for wounds between 20 and 50 mm were similar between wound tape and suture.

Torque motor tape winding characteristics and its connection with design parameters

The paper considers the features of a tape winding torque motor development. Novel motor type allows to obtain an increased torque by the high current flowing through the tape winding. It is shown that the most effective way of the torque increasing is the tape winding plate resistance reducing.

Optimization of Robot and Positioner Motions in Manufacturing of High-pressure Composite Vessels

Abstract The paper proposes a technique for optimal motions generation in redundant robotic tape winding systems for manufacturing of high-pressure composite vessels. It also presents two industrial case studies dealing with the motion generation for basic types of winding lamina, helical and circumferential. The developed technique transforms the original continuous problem into a discrete one where the desired time-optimal motions are presented as a shortest path on the task graph satisfying the problem-specific acceleration and velocity constraints imposed on the joint coordinates. It allows generating the optimal trajectories using enhanced dynamic programming algorithm that considers both of these constraints. Efficiency of the developed technique is confirmed by simulation studies.

Modeling and Simulation of Voids in Composite Tape Winding Process Based on Domain Superposition Technique

The tape winding technology is an effective way to fabricate rotationally composite materials. Nevertheless, some inevitable defects will seriously influence the performance of winding products. One of the crucial ways to identify the quality of fiber-reinforced composite material products is examining its void content. Significant improvement in products’ mechanical properties can be achieved by minimizing the void defect. Two methods were applied in this study, finite element analysis and experimental testing, respectively, to investigate the mechanism of how void forming in composite tape winding processing. Based on the theories of interlayer intimate contact and Domain Superposition Technique (DST), a three-dimensional model of prepreg tape void with SolidWorks has been modeled in this paper. Whereafter, ABAQUS simulation software was used to simulate the void content change with pressure and temperature. Finally, a series of experiments were performed to determine the accuracy of the model-based predictions. The results showed that the model is effective for predicting the void content in the composite tape winding process.

Dynamics modeling and deviation control of the composites winding system

During the composites winding process, running speed, tension fluctuation and other factors often lead to the tape deviation. To improve the winding precision and eliminate the running deviation, lateral dynamics of the tape winding is analyzed and mathematical model of the rectifying system is established. Then, a novel adaptive sliding mode controller (ASMC) is proposed, and principle of this control scheme is employing two fuzzy systems to approximate the nonlinear functions and utilizing another two fuzzy systems to adjust the feedback gain (FG) and switching gain (SG). Stability and convergence of the control system can be guaranteed by the Lyapunov theory and Barbalat Lemma. Simulation and experimental results show that the designed ASMC has highest control precision and much smaller input chattering when compared with other controllers.

Superconducting HTS coil made from round cable cooled by liquid nitrogen flow

The concept of simple cooling arrangement for superconducting coil made from a round cable based on high-temperature superconductor tapes is demonstrated. The cable architecture is similar to the Conductor on Round Core (CORC®) concept: it consists of eight superconducting tapes wound in two layers on a copper tube core in a helical manner. Such a Conductor on Round Tube hand-made cable 4 m long was used to wind the coil with eight turns on 14 cm diameter. Layers of commercial aerogel and polyurethane foam were applied to the coil to provide vacuum-less thermal insulation at its cooling by the flow of liquid nitrogen (LN) in the cable tube. The temperature of superconducting tapes was around 1 K above the coolant temperature in these conditions, causing about 16% reduction of the critical current compared to the LN bath cooling. Electromagnetic performance of the coil was calculated by the model based on the finite element method and the results compared with experimental observations.

Precision tension control technology of composite fiber tape winding molding

During the composite fiber tape winding process, tension fluctuation has a serious impact on the performance parameters of winding products, such as strength, compactness, resin content, fatigue resistance, and stress uniformity. Because of the influence of dynamic performance of tension control system caused by the torque motor, external disturbance, sensitivity of the parameter variation, inverter dead zone, ripple torque, cogging torque, nonlinear friction, and measurement noise, a fuzzy proportion integral derivative (PID) controller based on robust extended Kalman filter (REKF) is proposed, which considers membership function optimization of nonlinear dynamic fuzzy control system as systematic identification through designating activated membership function of input and output variable in each control step, and then, online adjustment of the activated membership functions is used to reduce the control error by REKF. By adjusting the shape and position of membership function, the designed controller can be adapted to the dynamic conditions. Simulation and experimental results show that overall performance of the control system has been significantly improved. Compared with traditional fuzzy PID, the fuzzy PID controller based on REKF has strong anti-interference performance and robustness, and the winding tension control precision has been increased by 40–42%.

Mechanical design of flywheels for energy storage: A review with state-of-the-art developments

For years, engineers and designers have capitalized on electrochemical batteries for long-term energy storage, which can only last for a finite number of charge–discharge cycles. More recently, compressed hydrogen is being scrutinized as a large-scale storage medium but this poses the risk of spreading high-pressure vessels with inflammable content. Historically, flywheels have provided an effective way to smooth out speed fluctuations in irregular machines and mechanisms. With advancements in composite materials, magnetic bearings, and mechatronic drives, flywheels have become the subject of extensive research as power storage devices for mobile or fixed installations. Flywheel energy storage systems are considered to be an attractive alternative to electrochemical batteries due to higher stored energy density, higher life term, deterministic state of charge and ecological operation. The mechanical performance of a flywheel can be attributed to three factors: material strength, geometry, and rotational speed. Focusing on the simple relationship between these variables, this paper reviews the literature of flywheel technology and explores the merits of four simple but unconventional flywheel configurations that have not been examined so far. Two geometries assume the use of monolithic isotropic materials two solutions are based on the use of high-strength strips or tapes wound up to form a multilayered structure.

Numerical reproduction of screening-current-induced fields in HTS tape windings using finite element method

The screening-current-induced fields in one of the high temperature superconducting (HTS) coils fabricated previously with coated conductors are evaluated numerically by using a one-dimensional finite element method, in which only the perpendicular component of a current vector potential is considered due to a very thin superconductor layer in the coated conductor. It is assumed that the voltage-current characteristics in the superconductor layer can be expressed by the critical state or n-value model, in which the field-dependent critical current density is also taken into account. The numerically calculated results of the screening-current-induced fields are compared with the experimental results carried out previously.