International Journal of Applied Electromagnetics and Mechanics - Volume Pre-press, issue Pre-press

Authors: Yao, Xing-Yan | Pecht, Michael

Article Type: Research Article

Abstract: Magnetorheological (MR) dampers are important devices for reducing and controlling vibration. Dynamic response time is one of the key factors that determines the control ability and application of the MR damper. Metal foam MR dampers are potentially superior to conventional dampers due to their low cost and fast response. The dynamic response time of metal foam MR dampers is distinct from conventional dampers. In this paper, the effects of different metal foam materials on the dynamic response time of metal foam dampers are studied. Three response time parameters were defined, and an experimental system including a DC motor, force sensor, …damper, and time relay was designed to collect dynamic response time parameter values using metal foam Cu and Ni, respectively. The experimental results show that the response time of MR dampers is faster using Ni rather than Cu metal foam due to the different permeability of the materials. The magnetic resistance model and Ansys simulation further prove that magnetic flux density is the main contributor to the differences in response time. Show more

Keywords: Magnetorheological (MR) fluid, MR damper, metal foam, dynamic response time

DOI: 10.3233/JAE-190022

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-15, 2019

Authors: Coufal, Oldřich | Bátora, Branislav | Radil, Lukáš | Toman, Petr

Article Type: Research Article

Abstract: A method is proposed for the calculation of current density in a long solid metallic conductor placed in an external variable magnetic field. The external magnetic field is perpendicular to the conductor and constant on straight lines parallel to the conductor. The conductor is passive, connected to neither a voltage source nor a current source. It is assumed that the external magnetic field is quasi-stationary and is not affected by the magnetic field of the currents induced in the conductor under examination. The frequency of external field does not exceed 1 MHz and the displacement current is neglected. The proposed method …enables the calculation of current density not only in the steady state but also in the case that the external field has an arbitrary time-dependent course. Results are given of the calculation of current density in conductors with symmetrical and unsymmetrical cross section, with constant and non-constant resistivity in the conductor cross section, for both homogeneous and non-homogeneous external steady-state sinusoidal field, and for switching the external sinusoidal field on and off. Show more

Keywords: Applied classical electromagnetism, magnetic induction, eddy currents, numerical simulation

DOI: 10.3233/JAE-180118

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-24, 2019

Authors: Li, Xiangchao | Ma, Xiaoqi | Liu, Yinping | Wan, Zhicheng | Cai, Lujin | Xu, Xiaopei

Article Type: Research Article

Abstract: Based on the invalidation and damage of the field effect transistors under lightning radiation, we establish the breakdown experiment with open-circuit voltage wave and the protection experiment with TVS as the protection device. The junction field effect transistor and the metal oxide semiconductor field effect transistor are used as material. We draw some conclusions. In the breakdown experiment, the breakdown voltage of the MOSFETs is higher than that of the JFETs as a whole. The MOSFET can be adopted in the amplifier circuit which is expected to get higher input resistance and breakdown voltage. The drain-source resistance can recover to …the original resistance value after being placed a period of time, but the gate-source resistance is irreversible. The invalidation of the device under test is due to the breakdown of gate-source. The TVS can protect the FTEs well. The change of pin resistance of the MOSFET is inconspicuous. MOSFETs are more stable for debugging and development of the amplifier circuit. The results provide some significance for the development and improvement of the lightning electric fields change measuring instruments in the future. Show more

Keywords: Field effect transistor, JFET, MOSFET, invalidation

DOI: 10.3233/JAE-180100

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-13, 2019

Authors: Ouili, M. | Mehasni, R. | Feliachi, M. | Belounis, A. | Latreche, M.E.H.

Article Type: Research Article

Abstract: The aim of this work is the investigation of the simultaneous separation of magnetic (𝜇r > 80) and conductive (𝜎 ≈ 6 ×107  S/m) particles in a designed magnetic separator. Such a separator consists mainly of a drum on which permanent magnets are arranged and a conveyor belt carrying the material to be purified. The separately driving of the drum and the conveyor belt allows the independent control of the frequency of the generated magnetic field and the displacement speed of the material to be treated. To generate high magnetic field, identical NdFeB permanent magnet bars with residual magnetic flux …density B r = 1.2 T are used. To compute the particles trajectories, the magnetic field and the particle dynamic governing equations have been solved using the numerical finite element (FEM) and Runge Kutta (RK4) methods. The computing results have shown that the proposed separator permits the simultaneous separation of magnetic and conductive particles. To check the validity of the numerical results, experiments have been carried out on ferromagnetic powder and conductive particles of different sizes. Show more

Keywords: Magnetic separation, drum, particle trajectories, finite element, permanent magnets

DOI: 10.3233/JAE-180101

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-19, 2019

Authors: Ye, Lezhi | Liu, Yupeng | Li, Desheng

Article Type: Research Article

Abstract: We propose a novel dual air-gaps and liquid-cooled eddy current retarder (ECR) based upon observing the (1) heat fade of the continuous braking and (2) large rotor weight of the traditional ECR for heavy vehicles. The new ECR maintains a low working temperature because of the liquid cooling stator structure. The eddy current distribution and braking torque characteristic curves are obtained by finite element method (FEM). Combining with 3-D FEM, Kriging approximation model is employed to optimize the structural parameters of rotor tooth. Based on the optimization method, the number of rotor teeth is determined to be 12. The braking …torque increases by 14.8% after optimization and the rotor tooth weight decreases by 9.5%, which reduces the adverse influence on the vehicle transmission system. The bench test was carried out to verify the optimized calculation results and the braking torque can be stepless controlled by adjusting the excitation current. Compared with traditional ECR, the dual air-gaps and liquid-cooled ECR has better continuous braking performance and is more suitable for heavy vehicle auxiliary braking. Show more

Keywords: Dual air-gaps, eddy current retarder, liquid cooling, Kriging model, structural optimization

DOI: 10.3233/JAE-180109

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-14, 2019

Authors: Zhang, Pengfei | Wang, Zhiheng | Xi, Guang

Article Type: Research Article

Abstract: This paper proposes a general multi-objective optimal design methodology for a new type of no-thrust-disk/thrust hybrid magnetic bearing that has been designed to reduce wind loss in centrifugal compressors. The approach dispenses with initial design results and has adjustable design objectives. To establish the proposed method we begin with its conceptual design, then look at how a parametric geometric model can facilitate manufacture, installation and cooling, before presenting a magnetic circuit model that can take into account eddy-current effects and significant magnetic leakage. The key optimization objectives selected include bearing capacity, mass, axial length, copper loss, iron loss, wind loss, …and outer diameter. The approach also takes into account the performance deterioration of permanent magnets at high temperatures. By using an optimization method that combines penalty factor and selection factor, we have been able to incorporate a function for adjusting and re-adjusting the optimization goals. To verify the validity of the approach we present a concrete design case. Out of four possible schemes, a scheme based on minimum mass and axial length proves to be the best solution in this example (assuming sufficient cooling capacity). Show more

Keywords: Thrust hybrid magnetic bearings (THMB), equivalent magnetic analysis, multi-objective optimization (MOO), eddy-current effect, wind loss

DOI: 10.3233/JAE-180062

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-30, 2019

Authors: Tang, Mingdong | Gu, Youlin | Wang, Shigang | Liang, Qinghua | Wang, Xiaoxi

Article Type: Research Article

Abstract: With the popularization of intelligent substations, hot-line working robots that can replace the manual operation without shutting down the power of the corresponding equipments are increasingly widely applied in the maintenance and monitoring of substations. Robotic operation can ensure the safety of the operators and reliability of operation while improving the economic benefits of substation. However, because of the compact structure of the intelligent substations, the operating space is small. Further, as the main material of hot-line working robots is metal, which greatly changes the strength and distribution of the electric field around its working position when entering the working …position and in the process of operation. In serious cases, interphases or phase to ground air breakdown occurs. Hence the working space of hot-line working robots is limited not only by the narrow space between devices in the substation but also by the electrical safety clearance of phase to phase and phase to ground. Therefore, it is necessary to find a safe working space (“SWS”) for the robot which should not be too small for the robot to accomplish the task effectively. The purpose of this paper is to provide: (i) a design reference for hot-line working robots which can not only guarantee the electrical safety distance but also minimize the effect to the electric field and (ii) a method to find the SWS of the robot in which the robot can accomplish the task effectively with the example of the hot-line working robot for isolated circuit breaker (“ICBot”). We analyze the influence of different installation positions and postures of the manipulators on the electric field in this paper and present a calculation method of the SWS of the manipulator in a very non-uniform electric field caused by the intervention of manipulators, which is significant to the research on hot-line working robots. The SWS has been tested in simulated and energized experimental system, and the experiment results show that the robot can work safely and efficiently. Show more

Keywords: Hot-line robot, electric field distortion, air breakdown, substation insulation

DOI: 10.3233/JAE-180057

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-14, 2019

Authors: Aguib, Salah | Nedjar, Ali | Zerrouni, Nassim | Djedid, Toufik | Tourab, Mohamed | Guedifa, Réda

Article Type: Research Article

Abstract: This paper is devoted to an experimental and theoretical study of the magneto-mechanical behavior of an elastomer loaded with 25% of ferromagnetic particles of micrometric size; elaborated under the action of a magnetic field. The characterization of the rheological properties and the interaction between the micron size ferromagnetic particles as a function of the intensity of the magnetic field are studied. The results obtained clearly show a high energy dissipation properties of the composite, accentuated by its modified structure from the interaction forces between the particles that are aligned, which gives adjustable viscoelastic structures properties, depending on the volume fraction …of particles and the magnetic field intensity. Show more

Keywords: Magneto-mechanical behavior, micrometric particles, rheological properties, magnetic force, elastomer

DOI: 10.3233/JAE-180108

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-13, 2019

Authors: Shi, Minxia | Zhang, Xuanrui | Qiu, Aici | Li, Junhao

Article Type: Research Article

Abstract: As the core material of electrical equipment, electrical steel sheet is often under rotational magnetization and DC-biased magnetization simultaneously. The rotating magnetic flux density, rotating magnetic field strength and total iron loss density under various DC-biased magnetizing condition are measured and analyzed in this paper to investigate the effects of DC magnetizing angle and amplitude on rotating magnetic properties. An improved model considering saturation and hysteresis is established for describing the rotating magnetic properties of electrical steel sheet under DC-biased field based on experimental results. It can be concluded that offset and distortion of the rotating magnetic parameters loci occur …with the increase of DC-biased magnetization. When the electrical steel sheet is magnetized to deep saturation, the total loss density decreases due to the diminishment of magnetic domain walls. The impact of DC-biased excitation on rotating properties is most obvious in hard magnetization direction. Show more

Keywords: Electrical steel sheet, DC-biased magnetization, rotating magnetic properties, iron loss density

DOI: 10.3233/JAE-180125

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-10, 2019

Authors: Wu, Jian | Sun, Jikang | Zhang, Tao | Sun, Hongbing | Ji, Sai | Sun, Yajie

Article Type: Research Article

Abstract: At present, the sampling rate in a wireless sensor network is generally low, which does not meet the requirements for high-speed sensor signal acquisition and detection. To address the shortcomings of wireless sensor networks in terms of the design methods and effects assessment, a high-speed wireless sensor network node was designed based on structural health monitoring. Based on the general framework of a wireless sensor node, combined with the requirement of active health monitoring, a test of screws loosening in a reinforced aluminum plate were conducted. The theory of compressed sensing was used to test the effects of compressed sampling …for the high-speed acquisition nodes. The results demonstrated that high-speed wireless sensor nodes could complete active excitation, sampling, and processing of the response signal for the application of active structure monitoring with integrated software and hardware and that the system could distinguish the looseness of the screws in the aviation specimens accurately. The nodes also met the requirements of small size, low cost, and low power consumption. The results of the experiment verified that the hardware and software modules for the high-speed wireless sensor nodes functioned and monitored the structural damage effectively. The system solves many key problems of node design in wireless sensor networks in the industrial field. Show more

Keywords: Wireless sensor network (WSN), structural health monitoring (SHM), high-speed sampling

DOI: 10.3233/JAE-170051

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-24, 2019