International Journal of Applied Electromagnetics and Mechanics - Volume 74, issue 2

Authors: Shen, Yanping | Liu, Ning | Sun, Mingliang | Wang, Biaobiao | Liang, Yuxia

Article Type: Research Article

Abstract: Permanent magnet eddy current brake (PMECB) with high damping performance is widely used in engineering vibration suppression and braking. In this study, based on the braking dynamics of PMECB under impact load, the analysis method related to the damping characteristics are established, including a static magnetic model with flux leakage, a uniform damping force model with demagnetization effect and skin effect, and an acceleration damping force model with magnetic field distortion. The comparison of the analysis method, numerical simulation and experimental results verifies that the analysis method can reproduce the damping law under impact load. The results show that the …maximum displacements of the analysis method and numerical simulation deviate from the experimental results within 3%. The analysis method can complete the calculation of the damping characteristics within a few seconds. The variations of the thickness, conductivity of the conductive cylinder, and air gap thickness have significant effects on the nonlinear and critical characteristics of the velocity-damping force curve, which can be corrected by changing the coefficients in the analysis method. In summary, the proposed analysis method can provide insights for rapid engineering design and optimization calculation of the PMECB by its completeness, accuracy, adaptability and rapidity. Show more

Keywords: Analysis method, eddy current brake, permanent magnets, impact load, numerical simulation

DOI: 10.3233/JAE-220194

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 74, no. 2, pp. 101-121, 2024

Authors: Wu, Lipeng | Zhang, Wenwei | Song, Xianjin | Liu, Guoqiang | Liu, Jing | Xia, Hui | Fan, Liguo

Article Type: Research Article

Abstract: Conventional low-frequency electromagnetic wave (LFEM) transmitting antennas are enormous in size, which limits the application of LFEM in underground space. Rotating-magnet Based Mechanical Antennas can realize the miniaturization of low-frequency antennas, which is expected to bring new possibilities for underground electromagnetic detection or ground penetration communication. Firstly, this paper establishes a synthetic field method for solving the electromagnetic field of a rotating permanent magnet in the air-earth cross-domain case. The method equates the magnet as an orthogonal superposition of vertical and horizontal dipole sources, and the phase difference between vertical and horizontal dipole sources is 𝜋/2. Based on the half-space …theory of multilayer planar media, the quasi-analytical solution of the electromagnetic field of the magnetic dipole in the case of air-earth trans dimensionality can be found by superposition. Secondly, based on the finite element numerical model, the trans-earth propagation characteristics of the electromagnetic field excited by the rotating permanent magnet across the air-earth dual domain are studied. At the same time, the radiation characteristics in the rotating plane of the permanent magnet are also studied. Again, this paper systematically investigates the influence of parameters such as earth conductivity, emission frequency, and propagation distance on the electromagnetic field propagation. Finally, the principle prototype is developed and experiments are carried out. The results show that the finite element numerical model established in this paper is correct, the experimental results are consistent with the theoretical values, and a field strength signal of 0.9 nT can be received at 20 m. The research work in this paper lays the foundation for the future use of mechanical antennas for electromagnetic detection and ground penetration communication. Show more

Keywords: Rotating-magnet based mechanical antenna, through-the-earth communication, homogeneous half space

DOI: 10.3233/JAE-230080

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 74, no. 2, pp. 123-139, 2024

Authors: Qian, Xusheng | Xu, Gaojun | Zhang, Xuancheng | Miao, Meng | Zhou, Yu

Article Type: Research Article

Abstract: At present, there are shoddy transformers in the market, of which the windings are replaced by aluminum and copper clad aluminum. The commissioning of these transformers may cause poor power supply performance and excessive winding heating. The existing detection methods of windings are complex, time-consuming to operate and destructive. Therefore, a winding material identification method based on vibration characteristics is proposed. Firstly, the vibration accelerations of transformer cores and windings with different winding materials are theoretically derived. Furthermore, through the coupling simulation of magnetic field and structure field of distribution transformers, the calculated vibration characteristics of copper, aluminum, and copper …clad aluminum are verified. Finally, by comparing the time domain, the frequency domain and time-frequency domain of acceleration signals, preliminary identification of winding materials is conducted, which lays a theoretical foundation for establishing a precise identification model for winding materials in the future. This work provides guarantee for the safe operation of the distribution network. Show more

Keywords: Transformer, identification of winding material, vibration characteristics, multi-physical field coupling, time-frequency analysis

DOI: 10.3233/JAE-230109

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 74, no. 2, pp. 141-153, 2024

Authors: Cheng, Gang | Song, Donghua

Article Type: Research Article

Abstract: Aiming at the shortcomings of the traditional permanent magnet governor air gap speed regulation, a sleeve-type electromagnetic hybrid governor is proposed by controlling the current instead of adjusting the air gap, the structural characteristics and working principle of the speed regulation model are introduced, and the electromagnetic torque mathematical expression is derived based on the equivalent magnetic circuit method, and the key parameters affecting the transmission performance of the governor are obtained, and the simulation model of the sleeve electromagnetic hybrid governor is established by using the finite element analysis method to analyze the electromagnetic field change law in the …governor under the transient field. The change curve of air gap magnetic inductance intensity under different currents was obtained, and the influence of speed difference under different currents on the output torque was revealed, and finally, an experimental platform was built for testing, and the maximum error of torque simulation and the test was obtained by analyzing the results to verify the accuracy of the simulation method, on this basis, two structural schemes were proposed to improve the amplitude of the torque regulation of the governor by the current, under the structure of scheme 1, the adjustment amplitude of the torque increased from 35% of the original structure to 96%, and the improvement effect was ideal. Its laws and conclusions can provide a reference for the further design and optimization of sleeve electromagnetic hybrid governor. Show more

Keywords: Sleeve type electromagnetic hybrid governor, equivalent magnetic circuit method, transient fields, speed regulation characteristics

DOI: 10.3233/JAE-230064

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 74, no. 2, pp. 155-168, 2024

Authors: Ye, Jianhua | Guo, Ze | Zeng, Shoujin | Xu, Mingsan

Article Type: Research Article

Abstract: A crack propagation trial was performed on a Q235 steel M(T) sample to investigate the modifications in magnetic memory signals throughout the crack propagation procedure of ferromagnetic substances. Various detection lines were employed to gather and scrutinize magnetic memory signals under two-stage fatigue loading. The interrelation between the gradient value K max , the peak-to-peak value S P − P y , the stress intensity factor K a , the extension of the sample 𝜀, crack length a , and the cyclic N was established. The findings indicate that the H p …(y ) curves present a varied peak at the crack tip and in the notch, whereas the H p (x ) curve is linear. The magnetic signals display similar changes during two-stage fatigue loading, but the post-break state deviates. The fatigue process’s S P − P y shows three phases of fluctuation, escalation, and decline. Throughout the period of fatigue crack growth, K max and 𝜀 rise exponentially, K a ascends linearly, and a shows linear changes. The characteristics of magnetic memory signals can measure harm after varying service periods and offer robust foundations for remanufacturing. Show more

Keywords: Metal magnetic memory, crack propagation, fatigue loading, remanufacturing

DOI: 10.3233/JAE-230050

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 74, no. 2, pp. 169-184, 2024

Authors: Chen, Zihan | Shen, Zhaoyang | Liu, Han | Shu, Xiang

Article Type: Research Article

Abstract: In this paper, a structurally simple transmissive all-dielectric metamaterial absorber is designed, fabricated and measured. The unit cell consists of photosensitive resin and water, which the water layers composed of rectangle loop, rectangular block and traffic circle. It achieves over 90% absorption of electromagnetic waves in the frequency range between 11.0 and 27.3 GHz. Meanwhile, three absorption peaks are located at 12.5, 18.4, and 26.0 GHz, which the absorptive are 97.4%, 98.3%, and 98.5%, respectively. In addition, the characteristics of the designed metamaterial reveal wide-incident angle absorption and polarization-insensitive properties. The experimental sample is measured by using the free-space method, and the …experimental results are verified to be in well agreement with the simulation data. Observing the distribution of electric and magnetic fields at different resonance frequencies, the physical mechanism of the absorption is attributed to strong magnetic resonance. Therefore, the proposed metamaterial has potential for widespread use in the fields of civilian and military. Show more

Keywords: Metamaterial, transmissive, all-dielectric, absorber

DOI: 10.3233/JAE-230208

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 74, no. 2, pp. 185-194, 2024