Low-frequency Broadband Lightweight Magnetic Composite Absorber Based on Metamaterial Structure

Optik ◽  
2021 ◽  
pp. 167619
Author(s):  
Wei Zhou ◽  
Zhenghou Zhu ◽  
Ruru Bai
Keyword(s):  
Low Frequency ◽  
Magnetic Composite ◽  
Metamaterial Structure

scholarly journals Low-frequency complex magnetic susceptibility of magnetic composite microspheres in colloidal dispersion

2007 ◽  
Vol 311 (1) ◽  
pp. 145-149 ◽  
Author(s):  
Ben H. Erné ◽  
Maria Claesson ◽  
Stefano Sacanna ◽  
Mark Klokkenburg ◽  
Emile Bakelaar ◽  
...  
Keyword(s):  
Magnetic Susceptibility ◽  
Low Frequency ◽  
Colloidal Dispersion ◽  
Magnetic Composite ◽  
Composite Microspheres

Low frequency sound insulation performance of asymmetric coupled-membrane acoustic metamaterials

2019 ◽  
Vol 15 (5) ◽  
pp. 1006-1015
Author(s):  
Mengna Cai ◽  
Hongyan Tian ◽  
Haitao Liu ◽  
Yanhui Qie
Keyword(s):  
Low Frequency ◽  
Sound Insulation ◽  
Asymmetric Structure ◽  
Insulation Material ◽  
Metamaterial Structure ◽  
Content Type ◽  
Acoustic Metamaterial ◽  
Frequency Sound ◽  
Membrane Type ◽  
Insulation Performance

Purpose With the development of the modern technology and aerospace industry, the noise pollution is remarkably affecting people’s daily life and has been become a serious issue. Therefore, it is the most important task to develop efficient sound attenuation barriers, especially for the low-frequency audible range. However, low-frequency sound attenuation is usually difficult to achieve for the constraints of the conventional mass-density law of sound transmission. The traditional acoustic materials are reasonably effective at high frequency range. This paper aims to discuss this issue. Design/methodology/approach Membrane-type local resonant acoustic metamaterial is an ideal low-frequency sound insulation material for its structure is simple and lightweight. In this paper, the finite element method is used to study the low-frequency sound insulation performances of the coupled-membrane type acoustic metamaterial (CMAM). It consists of two identical tensioned circular membranes with fixed boundary. The upper membrane is decorated by a rigid platelet attached to the center. The sublayer membrane is attached with two weights, a central rigid platelet and a concentric ring with inner radius e. The influences of the distribution and number of the attached mass, also asymmetric structure on the acoustic attenuation characteristics of the CMAM, are discussed. Findings In this paper, the acoustic performance of asymmetric coupled-membrane metamaterial structure is discussed. The influences of mass number, the symmetric and asymmetry structure on the sound insulation performance are analyzed. It is shown that increasing the number of mass attached on membrane, structure exhibits low-frequency and multi-frequency acoustic insulation phenomenon. Compared with the symmetrical structure, asymmetric structure shows the characteristics of lightweight and multi-frequency sound insulation, and the sound insulation performance can be tuned by adjusting the distribution mode and location of mass blocks. Originality/value Membrane-type local resonant acoustic metamaterial is an ideal low-frequency sound insulation material for its structure is simple and lightweight. How to effectively broaden the acoustic attenuation band at low frequency is still a problem. But most of researchers focus on symmetric structures. In this study, the asymmetric coupled-membrane acoustic metamaterial structure is examined. It is demonstrated that the asymmetric structure has better sound insulation performances than symmetric structure.

Shape optimization of soft magnetic composite inserts for electromagnetic stirrer with traveling magnetic field

2020 ◽  
Vol 39 (1) ◽  
pp. 28-35
Author(s):  
Kirill Bolotin ◽  
Evgeniy Leonidovich Shvidkii ◽  
Igor Sokolov ◽  
Sergey Alekseevich Bychkov
Keyword(s):  
Liquid Metal ◽  
Three Dimensional ◽  
Low Frequency ◽  
Magnetic Composite ◽  
Shape Effect ◽  
Soft Magnetic ◽  
Electrodynamic Force ◽  
Content Type ◽  
Finite Element Software ◽  
Soft Magnetic Composite

Purpose The purpose of this paper is to search optimal shape of soft magnetic composite-based inserts used to compensate the working gap between the liquid metal and the induction stirrer in metallurgical installations. Design/methodology/approach The study was based on numerical simulation of electromagnetic processes in frequency domain. To optimize inserts shape, the Nelder–Mead method was used. The maximum of integral electrodynamic force along x-axis was chosen as the objective function. All simulations were performed in finite element software package Comsol Multiphysics. Findings Optimal inserts shape was determined, at which the value of integral electrodynamic force along x-axis increased by 20% from 692  to 792 N. Originality/value Magnetic concentrators based on soft magnetic composite materials have long been used in high-frequency systems; at the same time, their use in low-frequency systems has not been previously considered in detail. The study of the shape effect of concentrators on the effectiveness of electromagnetic field in a liquid metal in a three-dimensional formulation was carried out for the first time.

scholarly journals High-Temperature and Low-Frequency Acoustic Energy Absorption by a Novel Porous Metamaterial Structure

2021 ◽  
Author(s):  
Qihang Liu ◽  
Xuewei Liu ◽  
Chuanzeng Zhang ◽  
Fengxian Xin
Keyword(s):  
High Temperature ◽  
Theoretical Model ◽  
Porous Material ◽  
Energy Absorption ◽  
Low Frequency ◽  
Acoustic Energy ◽  
Frequency Range ◽  
Metamaterial Structure ◽  
Equivalent Inclusion ◽  
Absorption Performance

AbstractIn this paper, we propose a novel porous metamaterial structure with an improved acoustic energy absorption performance at high-temperature and in the low-frequency range. In the proposed novel porous metamaterial structure, a porous material matrix containing periodically perforated cylindrical holes arranged in a triangular lattice pattern is applied, and additional interlayers of another porous material are introduced around these perforations. The theoretical model is established by adopting the double porosity theory for the interlayer and the cylindrical hole which form an equivalent inclusion and then applying the homogenization method to the porous metamaterial structure formed by the equivalent inclusion and the porous matrix. The temperature-dependent air and material parameters are considered in the extended theoretical model, which is validated by the finite element results obtained by COMSOL Multiphysics. The acoustic or sound energy absorption performance can be improved remarkably at very low frequencies and high temperature. Furthermore, the underlying acoustic energy absorption mechanism inside the unit-cell is investigated by analyzing the distribution of the time-averaged acoustic power dissipation density and the energy dissipation ratio of each constituent porous material. The results reveal that regardless of the temperature, the acoustic energy is mostly dissipated in the porous material with a lower airflow resistivity, while the acoustic energy dissipated in the porous material with a higher airflow resistivity also becomes considerable in the high-frequency range. The novel porous metamaterial structure proposed in this paper can be efficiently utilized to improve the acoustic energy absorption performance at high temperature.

Modeling and Dynamics of Magnetically Repulsive Negative Stiffness Permanent Magnetic Array for Precision Air/Magnetic Composite Vibration Isolation

2021 ◽  
Author(s):  
Yamin Zhao ◽  
Junning Cui ◽  
Limin Zou ◽  
Zhongyi Cheng
Keyword(s):  
Vibration Isolation ◽  
Permanent Magnets ◽  
Structural Parameters ◽  
Low Frequency ◽  
Vertical Direction ◽  
High Amplitude ◽  
Negative Stiffness ◽  
Magnetic Composite ◽  
Experimental Systems ◽  
Vibration Transmissibility

To reduce the natural frequency of air isolators and realize low or ultra-low frequency air/magnetic composite vibration isolation with large payloads, a magnetically repulsive negative stiffness permanent magnetic array (MRNSPMA) is proposed. Specifically, we utilize cuboidal permanent magnets to form a spatial array that is mechanically repulsive in the horizontal direction and structurally parallel in the vertical direction. The superiority of MRNSPMA in achieving high amplitude negative stiffness is verified. Furthermore, the effects of structural parameters on vibration transmissibility under the base and force excitations are investigated with the introduction of MRNSPMA. The displacement transmissibility, the force transmissibility and the frequency corresponding to the peak transmissibility are significantly reduced, validating the promise of MRNSPMA for improving the isolation performance of cutting-edge scientific experimental systems and facilities.

Investigations on Different Processing Conditions on Soft Magnetic Composite Material Behavior at Low Frequency

2012 ◽  
Vol 48 (4) ◽  
pp. 1335-1343 ◽  
Author(s):  
Marco Actis Grande ◽  
Róbert Bidulsky ◽  
Andrea Cavagnino ◽  
Luca Ferraris ◽  
Paolo Ferraris
Keyword(s):  
Composite Material ◽  
Low Frequency ◽  
Material Behavior ◽  
Magnetic Composite ◽  
Processing Conditions ◽  
Soft Magnetic ◽  
Soft Magnetic Composite

scholarly journals Enhancing the Low-Frequency Induction Heating Effect of Magnetic Composites for Medical Applications

Polymers ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 386 ◽  
Author(s):  
Ziyin Xiang ◽  
Khao-Iam Jakkpat ◽  
Benjamin Ducharne ◽  
Jean-Fabien Capsal ◽  
Jean-François Mogniotte ◽  
...  
Keyword(s):  
Induction Heating ◽  
Magnetic Particles ◽  
Varicose Veins ◽  
Local Heating ◽  
Low Frequency ◽  
Experimental Tests ◽  
Medical Applications ◽  
Magnetic Composite ◽  
Magnetic Composites ◽  
Frequency Excitation

This study aims to enhance the low-frequency induction heating (LFIH) effect in a thermoplastic polymer doped with iron oxide magnetic particles, which are promising candidates for several medical applications thanks to their confirmed biocompatibility. Two main approaches were proposed to successfully boost the heating ability; i.e., improving the magnetic concentration of the composite with higher filler content of 30 wt %, and doubling the frequency excitation after optimization of the inductor design. To test the magnetic properties of the ferromagnetic composite, a measurement of permeability as a function of temperature, frequency, and particle content was carried out. Thermal transfer based COMSOL simulations together with experimental tests have been performed, demonstrating feasibility of the proposed approach to significantly enhance the target temperature in a magnetic composite. These results are encouraging and confirmed that IH can be exploited in medical applications, especially for the treatment of varicose veins where local heating remains a true challenge.

scholarly journals Low frequency and broadband metamaterial absorber with cross arrays and a flaked iron powder magnetic composite

AIP Advances ◽  
2018 ◽  
Vol 8 (1) ◽  
pp. 015318 ◽  
Author(s):  
Wangchang Li ◽  
Qing Liu ◽  
Liwei Wang ◽  
Zuzhi Zhou ◽  
Jingwu Zheng ◽  
...  
Keyword(s):  
Iron Powder ◽  
Low Frequency ◽  
Metamaterial Absorber ◽  
Magnetic Composite

A Study on the Fine Structure of the Lateral Line Organ of the Sea Eel

1973 ◽  
Vol 31 ◽  
pp. 648-649
Author(s):  
K. Hama
Keyword(s):  
Fine Structure ◽  
Electron Microscope ◽  
Lateral Line ◽  
Low Frequency ◽  
Sensory Cells ◽  
Apical Surface ◽  
Voltage Electron ◽  
Sensory Epithelia ◽  
Low Frequency Vibration ◽  
Transmission Electron

The lateral line organs of the sea eel consist of canal and pit organs which are different in function. The former is a low frequency vibration detector whereas the latter functions as an ion receptor as well as a mechano receptor.The fine structure of the sensory epithelia of both organs were studied by means of ordinary transmission electron microscope, high voltage electron microscope and of surface scanning electron microscope.The sensory cells of the canal organ are polarized in front-caudal direction and those of the pit organ are polarized in dorso-ventral direction. The sensory epithelia of both organs have thinner surface coats compared to the surrounding ordinary epithelial cells, which have very thick fuzzy coatings on the apical surface.

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