Abstract:Over braiding of superconducting Rutherford cable was used for fibre reinforcement in the composite insulation in this research. Braiding was a suitable alternative to fabric tape winding for achieving ultrathin insulation with required electrical breakdown voltage. A brief overview of the superconducting magnets, their application and requirements of insulation has been covered in order to bridge the literature gap between braiding and the superconducting magnet field of studies. Organic size coating on the f… Show more
“…This unevenness of surface coverage was previously reported in the similar conditions. 24 Figure 13.Comparison of yarn spacing predicted by the theoretical relation, and experimental measurements for rectangular cross section mandrel.…”
Braided preforms are used in many applications to make modern textile composites. Mechanical properties of braided composites are strongly dependent on braided preform’s characteristics such as braid angle and yarn spacing. In this paper, theoretical relationships are presented to predict these parameters in braiding of a mandrel with flat faces. These relationships are very simple in deriving and coding and also they are suitable for sharp edges. It was observed that considering the distance between the yarn’s fell point on the mandrel and guide ring plane is an important issue to calculate an accurate braid angle. Braid angle and yarn spacing was also measured experimentally. Theoretical relations predictions are in close agreement with experimental measurements. The effects of the mandrel aspect ratio and the mandrel eccentricity to produce a part with variable braid angle are investigated. It is observed that while mandrel dimension aspect ratio has no significant effect, the braid angle can be considerably varied from one face to another face by locating the mandrel out of the center of the machine. An optimization process is proposed to find the best mandrel eccentricity to manufacture a preform with desired braid angles on individual faces.
“…This unevenness of surface coverage was previously reported in the similar conditions. 24 Figure 13.Comparison of yarn spacing predicted by the theoretical relation, and experimental measurements for rectangular cross section mandrel.…”
Braided preforms are used in many applications to make modern textile composites. Mechanical properties of braided composites are strongly dependent on braided preform’s characteristics such as braid angle and yarn spacing. In this paper, theoretical relationships are presented to predict these parameters in braiding of a mandrel with flat faces. These relationships are very simple in deriving and coding and also they are suitable for sharp edges. It was observed that considering the distance between the yarn’s fell point on the mandrel and guide ring plane is an important issue to calculate an accurate braid angle. Braid angle and yarn spacing was also measured experimentally. Theoretical relations predictions are in close agreement with experimental measurements. The effects of the mandrel aspect ratio and the mandrel eccentricity to produce a part with variable braid angle are investigated. It is observed that while mandrel dimension aspect ratio has no significant effect, the braid angle can be considerably varied from one face to another face by locating the mandrel out of the center of the machine. An optimization process is proposed to find the best mandrel eccentricity to manufacture a preform with desired braid angles on individual faces.
“…Braiding technology is a mature textile processing technology with simple processes and efficient production, and it has been widely used to braid industrial ropes, medically braided artificial blood vessels, and 1D energy harvesting and storage devices. − The 1D supercapacitor prepared by braiding technology has the advantages of stable structure, excellent mechanical properties, weavability and continuous preparation . However, the design of a 1D supercapacitor with a tubular structure using braiding technology has not been studied so far.…”
Strain sensors with wearable and self-powered characteristics have great potential in areas such as the detection of human motion and human−machine interface technology. However, most current self-powered sensors are based on twodimensional (2D) planar structures, and the overall weight and size of such integrated devices are relatively large. Here, an integrated wearable fibrous self-powered sensing device consisting of a braided-based asymmetric tubular supercapacitor (BATSC) and a carbon nanotube/polyester@rubber braided thread (CNT/PRBT) fibrous strain sensor is presented. The BATSC braided by a onestep braiding method exhibits a high linear energy density (23.5 μWh cm −1 at a power density of 67.8 μW cm −1 ) and excellent electrochemical stability performance (92.2% capacitance retention after 6000 bending−recovering cycles; the initial capacitance remains almost constant at dynamic bending different angles). The fibrous self-powered strain sensing device has reliable selfpowered sensing performance and can be sewn onto textiles or tied directly as a portable self-powered strain sensor for real-time detection of human joint motion (fingers, elbows, and knees), which has potential applications in wearable intelligent motion monitoring and rehabilitation training areas. The design and integration strategy of the fibrous self-powered sensing device provides insights for the development of fibrous multifunctional wearable products.
“…Numerous approaches, some complementary and some mutually exclusive, have been proposed to mitigate interface problems. These can be summarized as: (a) replacing all bonded interfaces by sliding interfaces; (b) replacing the epoxy system with brittle substances like paraffin or beeswax that releases less energy upon fracture [24]; (c) increasing the epoxy's fracture toughness [21]; (d) using filled epoxy systems in order to reduce differential thermal contraction; (e) removing reaction residues and dirt from interfaces [19,25]; and (f) increasing heat capacity [26]. Given the typical time-and cost-considerations of superconducting magnet R&D, only a limited number of ideas can normally be implemented in R&D magnets, and more exotic approaches are thus hardly ever tested.…”
For 30 years, training and unpredictable degradation in accelerator type high-field Nb3Sn magnets have seriously hampered Nb3Sn application. Training and deterioration have to be solved or at least better controlled. The global picture shows that most of the R&D and short model magnets start to train at some 40%–70% of the critical current and then creep up to almost the critical current within some 10–50 training steps. A typical class of failures leading to quenches is largely characterized by cracking and debonding at the interfaces between cable and glass-resin insulation, as well as between insulation and coil former. The study of training by means of testing demonstrator coils is rather expensive and time consuming. However, advances in magnet design and fabrication can also be assessed and benchmarked using BOX, the bonding experiment presented here, that produces maximum uniaxial Lorentz forces at some 7.5 T in a controlled experiment performed in 11 T solenoid facility at the University of Twente. BOX samples use only one meter of Nb3Sn cable inserted in a three-wave meandering slot in a flat metallic sample holder, reproducing magnet-relevant interactions between cable, insulation, impregnated materials and coil former. The meander shape exposes seven straight cable sections to a transverse magnetic field, thereby generating a representative level of shear stress at the interfaces. In this way, characteristic training curves of magnets can be mimicked and solutions studied. We aim to demonstrate with various samples failure mechanisms of high-field Nb3Sn magnets without the need to manufacture complete magnets. BOX may thus be expected to allow for quick and affordable testing of novel insulations, impregnation materials, coatings and interfaces for Nb3Sn magnets achieved by investigating various resins, fillers and more.
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