International Journal of Applied Electromagnetics and Mechanics - Volume 53, issue 2

Authors: Shen, Na | Zhang, Xiangjin | Liao, Qiaosheng | Zhang, Miao

Article Type: Research Article

Abstract: During a launch with an electromagnetic railgun its payload is subjected to both extreme mechanical stresses and strong electromagnetic interference. Therefore, the design of electronic parts of the payload, such as a fuse of an ammunition, poses technical challenges. This paper focuses on the magnetic shielding technique of intelligent ammunition fuses. After considering the magnetic field distribution including the velocity skin effect, a surface model of a railgun was built. Double exponential pulses similar to capacitor discharges were used as power supply. Spatial distribution regularities and frequency spectrum characteristics of pulsed strong magnetic field in the chamber of the rail …gun were analyzed. Based on these results a simulation and an experimental analysis of the shielding effectiveness of a strong magnetic field environment designed for a railgun payload was conducted. The shielding effectiveness of different shield materials, located at different distances in front of the armature and at different positions inside the shield. The results indicated the feasibility of effectively shielding the strong magnetic field in the chamber of a railgun during the launch. These findings can serve as a reference for future railgun intelligent ammunition shielding designs. Show more

Keywords: The electronic-magnetic rail gun, ammunition fuse, magnetic shielding technique

DOI: 10.3233/JAE-160060

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 53, no. 2, pp. 337-358, 2017

Authors: Gao, Hui | Song, Le

Article Type: Research Article

Abstract: For the high-speed rotation characteristics of maglev flywheel, in order to reduce the vibration impact of shared frequency sinusoidal signal with the flywheel, an improved variable step size least mean square (LMS) algorithm is proposed through analyzing the application deficiency in maglev flywheel system of the standard LMS algorithm and original variable step size LMS algorithm. The filtering compensation effect is compared of the proposed LMS algorithm with the original algorithm. Simulation results show that the modified algorithm having better convergence and follow the desired signal ability to time-varying small amplitude signals. The study can offer help to improve the …control stability and compensation real-time performance for maglev flywheel system. Show more

Keywords: Maglev flywheel, frequency mismatch, variable step-size LMS algorithm, frequency time-varying, adaptive filtering

DOI: 10.3233/JAE-160068

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 53, no. 2, pp. 359-369, 2017

Authors: Harzallah, Salaheddine | Chabaat, Mohamed

Article Type: Research Article

Abstract: A new approach for computing fracture mechanics parameters such as the Stress Intensity Factor (SIF) and the Energy Release Rate (J) by measuring and testing related Eddy currents is presented. These parameters are evaluated using the variation of the impedance. In the process, a magnetic vector is formulated from the theoretical set up and obtained results from relevant applications are checked for the theory consistency. Besides, cracks detection as well as their propagationis are studied through the two parameters SIF and J-integral. A simulation by a numerical approach using Finite Element discretization of 3-D governing equations is employed to detect …damaged zones and cracks. Obtained results are compared and agreed with those of other researchers. Show more

Keywords: 3-D eddy currents, fracture mechanics, stress intensity factor, j-integral, impedance variation

DOI: 10.3233/JAE-160073

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 53, no. 2, pp. 371-385, 2017