(Vol. 1, part of 2 vols set) Size: 22x14cm., Contents: Chapter I. Tension and Compression within the Elastic Limit II. Analysis of Stress and Strain III. Bending Moment and Shearing Force IV. Stresses in Laterally Loaded Symmetrical beams V. Deflection of Laterally Loaded Symmetrical Beams VI. Statically Indeterminate Problems in Bending VII. Symmetrical Beams of Variable Cross Section-Beams of Two Materials VIII. Bending of Beams in a plane which is not a Plane of Symmetry IX. Combined Bending and Axial Load Theory of Columns X. Torsion and Combined Bending and Torsion XI. Strain Energy and Impact XII. Curved Bars Appendix A: Moments of Inertia of Plane Areas Appendix B. Tables of Structural Shapes Author Index Subject Index. ISBN:8123910304 xiv+442 Yr. of Pub.reprint 2004Paper Back

Strength of materials ..

Second-generation high-temperature superconductors (HTS) REBCO are promising for high-field application due to the excellent $j_{c}(B)$ performance at low temperatures and for power transmission at liquid nitrogen temperature. For power transmission with HTS, the formation of high-current HTS cables from single HTS tapes is desirable for cable currents of several 10 kA up to more than 100 kA. On the other hand, to avoid high inductances, which would cause high-voltage problems in case of quench or fast shutdown, high-current HTS cables are needed for larger high-field magnets, too, typically operated at 4.5 K or lower. In the last years, several HTS cable designs have been proposed, such as twisted stacked cable, CORC cable, and Roebel cable. This talk will give an overview of such proposals and highlight actual developments in HTS cable design and REBCO tape optimization, e.g., for highest field. In addition, an optimization of round TSTC strand will be introduced, which is designed for simple fabrication in long lengths for versatile use either for the production of cables to be used at high fields or for power transmission.

High-Current HTS Cables: Status and Actual Development

Along with advancements in superconducting technology, especially in high-temperature superconductors (HTSs), the use of these materials in power system applications is gaining outstanding attention. Due to the lower weight, capability of carrying higher currents, and the lower loss characteristic of HTS cables, compared to conventional counterparts, they are among the most focused large-scale applications of superconductors in power systems and transportation units. In near future, these cables will be installed as key elements not only in power systems but also in cryo-electrified transportation units, that take advantage of both cryogenics and superconducting technology simultaneously, e.g., hydrogen-powered aircraft. Given the sensitivity of the reliable and continuous performance of HTS cables, any failures, caused by faults, could be catastrophic, if they are not designed appropriately. Thus, fault analysis of superconducting cables is crucial for ensuring their safety, reliability, and stability, and also for characterising the behaviour of HTS cables under fault currents at the design stage. Many investigations have been conducted on the fault characterisation and analysis of HTS cables in the last few years. This paper aims to provide a topical review on all of these conducted studies, and will discuss the current challenges of HTS cables and after that current developments of fault behaviour of HTS cables will be presented, and then we will discuss the future trends and future challenges of superconducting cables regarding their fault performance.

https://iopscience.iop.org/article/10.1088/1361-6668/ac7ae2/pdf

High temperature superconducting cables and their performance against short circuit faults: current development, challenges, solutions, and future trends

A 10 MW class data center with ultra-dense high-efficiency energy distribution: Design and economic evaluation of superconducting DC busbar networks

This paper mainly presents an ac loss numerical study of quasi-isotropic strands fabricated by second generation wires in cryogenic temperatures of 4.2 and 77 K. In order to estimate the ac losses accurately, a scaling relation of critical current density depending on the magnetic field and magnetic field angle with wire is adopted in the model. AC loss contributions, including hysteresis and eddy current losses, are estimated in detail at 5-Hz magnetic field with amplitude range from 0.1 to 7 T. At low fields and 4.2 K temperature, hysteresis losses of quasi-isotropic strands are less than the eddy current losses (which mainly comes from the copper sheath), this situation is very different from the 77 K. Effects of the magnetic field frequency and orientation with a strand on ac losses are also particularly analyzed under different magnetic fields. The numerical results are helpful for overall understanding on ac loss characteristics of quasi-isotropic strands and are also useful for their applications in high magnetic field at low temperatures.

AC Loss Analysis on a Quasi-Isotropic Strand Stacked by 2G Wires by Numerical Simulation in Cryogenic Temperature

The high-temperature superconducting (HTS) strand, with high current capacity and a round or square cross section, is expected to have widely potential applications in current leads and superconducting power devices since it is easily insulated to avoid point charging. This paper describes a quasi-isotropic strand made from coated conductors. The magnetic field distribution and critical current characteristic of the strand in self-field are simulated by the finite-element method and tested in liquid nitrogen. The result indicates that this strand has high current-carrying capacity. The critical currents in different external magnetic fields and various orientations were measured. It is verified by the experiments that the strand has isotropic characteristics in low magnetic field and weak anisotropy in higher field. The potential of the strands with high engineering current density makes them also suitable for high-field magnets and high-voltage power applications, while maintaining flexibility.

Investigation on Critical Current Properties of Quasi-Isotropic Strand Made From Coated Conductors

High-temperature superconducting (HTS) materials, especially REBCO coated conductors (CCs), are promising for the application of high field magnets, current leads, and power devices. However, the current capacity is limited for a single CC. In recent years, several prototypes of cable, conductor, and strand were proposed and demonstrated in order to increase current capacity. Except for the high current capacity, the mechanical property is other one of the important factors in practical applications. This paper numerically analyzed the mechanical characteristics of a quasi-isotropic strand composed of four substrands by stacking ReBCO CCs in parallel, which mainly include dependencies of bending radii and twisting pitches on critical currents. The strain distributions of the strand in bending and twisting as well as combination of bending with twisting were calculated by the simulation method. The results are useful in application of high field and large-scale magnet and current lead in low temperature.

Simulations of Bending and Twisting Mechanical Characteristics of a Cable Strand Made of REBCO Conductors at Cryogenic Temperatures

With the development of second generation (2G) high-temperature superconducting (HTS) tapes, several cabling configurations, such as twisting stacked-tapes cable and conductor on round core cables, have been proposed, and some prototypes were developed. Alternating current (ac) losses arise in HTS tapes in ac operations, and those losses are an important consideration for applications since they influence the stability and operating cost. Conventionally, a twisting technique is used to effectively reduce the ac losses. This paper presents the twisting properties and tensile properties of a quasi-isotropic (QI) strand made from 2G tapes. The strand consists of 2G tapes, aluminum foil, and a metal sheath. A twisting apparatus was designed and demonstrated to research the characteristics of the strands in twisting situations. The critical currents and strain of a single CC were tested for different twist pitches in self-field and at 77 K. The results show that the critical twist pitch of the QI strand is higher than that of a single tape. The critical current of the QI strand was also measured at 77 K after the application of different tensile stresses at room temperature.

Twisting Characteristics and Tensile Effects of a Quasi-Isotropic Strands Made of Coated Conductors

This paper presents the quench behavior of isotropic strands made from second-generation (2G) coated conductors (CCs) subjected to overcurrent at power frequency and liquid nitrogen, in order to evaluate their prospects for power applications. The isotropic strands with high current capacity, consisting of CCs in parallel, were prepared by putting them into different metal sheaths using industrial soldering techniques and drawing as well as extrusion processes. Current over the critical current was supplied to the sample strands, with a duration of 700 ms, at 77 K. Profiles of the voltage, current, and temperature in the sample strand were recorded during the pulsing overcurrent test. Based on the U(t) and I(t) curves, the resistance of sample strands and phase angle between voltage and current were also obtained. After each pulsing current, the critical current and n-values of the sample strands were retested. The results show that quench characteristics of the sample strands with different sheaths are very different from each other. Additionally, the sample strand fabricated by stainless-steel sheath has stronger current-limited ability than the copper or aluminum sheaths.

Quench Behavior of Isotropic Strand Made From Coated Conductors With Overcurrent at Power Frequency

Comparing with direct current (dc) conventional transmission lines, dc high-temperature superconducting (HTS) power cables have advantages of high current, low transmission loss, and environmental friendly characteristics. With regard to HTS cables with coaxial configuration and self-shielding functions, this type of cable has a “sandwich” structure that is obtained by interleaving the windings for the minimization of the magnetic field and the degradation of the critical current. This paper proposes a two-dimensional (2-D) model for simulating magnetic field distributions, such that the critical current distribution can be found precisely. The ac loss is also analyzed since the current in the dc transmission is comprised of dc and ac ripple. This 2-D analysis model provides a useful reference for the design and operation of dc HTS cables with large current capacity without magnetic field disturbance.

Jiping Xue

Papers

Investigation on Critical Current Properties of Quasi-Isotropic Strand Made From Coated Conductors

Simulations of Bending and Twisting Mechanical Characteristics of a Cable Strand Made of REBCO Conductors at Cryogenic Temperatures

Twisting Characteristics and Tensile Effects of a Quasi-Isotropic Strands Made of Coated Conductors

Quench Behavior of Isotropic Strand Made From Coated Conductors With Overcurrent at Power Frequency

Electromagnetic Field Analysis of a High Current Capacity DC HTS Cable With Self-shielding Characteristic by 2-D Simulation