Middle Metal Layer Research Articles

The Effect of Core Metal Layer Thickness on the Behavior of Carall Under Low Velocity Impact Loading

Fiber metal laminates are the advanced composite materials, in which the metal and FRP layers are stacked alternatively to achieve the desired properties. The presence of FRP layers enhances the fatigue, fracture properties and weight savings. Durability and plasticity of the metal plays a significant role in the design of fiber metal laminates. This study evaluates the role of middle metal layer (core) thickness on the behavior of Carall fiber metal laminates under low velocity impact loading. Two types of Carall 3/2 with middle layer of varying thickness are considered. The metal volume fraction is same for both the laminates. Finite element simulations have been carried out for the laminates considered according to the standard ASTM D7136. Johnson–cook plasticity and damage model and two-dimensional Hashin damage criteria have been used to model the aluminum and CFRP respectively. From the study, it was found that the placement of thicker layer at the middle position in the Fiber metal laminate enhances the impact resistance of Carall. The energy absorption studies also indicate that the presence of thicker layer at the middle position increases the energy absorption capability.

Strain effects on the electronic and magnetic properties of Cr2TaC2 and Cr2TaC2O2 monolayers

Double transition metal MXene materials, such as Cr2TiAlC2, were successfully synthesized recently in addition to the synthesized mono transition metal MXenes. The physical and chemical properties of the MXenes can be tuned by varying the middle metal layer composition by other metal atoms. Thus, the desired mechanical, electronic, thermal, or magnetic properties can be revealed in that MXene material. The other method to tune material properties is by applying external strain on the structure. In this study, we systematically investigate the physical properties, such as dynamical, thermal, mechanical stability, electronic, and magnetic properties of the Cr2TaC2 and the Cr2TaC2O2 MXene monolayers for equilibrium and under biaxial strain. We find that both of MXene monolayers are energetically, thermally, and dynamically stable for certain compressive and tensile strain values. The Cr2TaC2 and the Cr2TaC2O2 MXene monolayers have a ferromagnetic ground state and show a metallic character in an equilibrium state and preserve it up to high tensile strain (ε = 0.10) value. The robust ferromagnetism above room temperature is demonstrated for the Cr2TaC2 with a Curie temperature of 714 K for the strain-free case. This value reduces to 234 K for the Cr2TaC2O2 monolayer. Moreover, our detailed Monte Carlo simulations reveal that the magnetic transition temperature of the system and also hysteresis properties can be controlled by moving from compressive to tensile strain ratios.

Fundamental understanding of open keyhole effect in plasma arc welding

The keyhole arc welding technique has the advantage of improving welding efficiency by utilizing a stable keyhole mode. Accurate understanding of the keyhole effect is necessary to enhance the welding quality. Due to the high temperature and strong arc force involved, the complex gas–liquid–solid interactions in the complete keyhole process need to be explored. In order to fully demonstrate open keyhole mode welding, a three-tier sandwiched model based on multiphysics and multiphase effects was developed. The top layer of the model is filled with plasma arc, which gradually fuses and penetrates through the middle metal layer. Finally, it enters the third layer, resulting in an open keyhole mode. Multiphysics phenomena due to the plasma arc are fully included in the model, and the gas–liquid–solid interactions are calculated by combining the Volume of Fluid technique and the Enthalpy-porous technique. Arc ignition and dynamic open keyhole effect are demonstrated, and an arc discharge is shown from the open keyhole exit. The arc reflection phenomenon is observed as the arc is blocked by the weld pool frontier. The electric current path varies with the welding movement, and most of the current comes from the weld pool frontier. An experiment was conducted to obtain weld pool and keyhole images, which basically agree with the calculated results. Additionally, the calculated open keyhole time and electric potential drops also coincide well with experimental data.

Single-Polarized Low-Profile High-Order Bandpass Frequency Selective Surfaces Based on Aperture-Coupled Patch Resonators Under TM and TM Modes

This communication presents a methodology to construct the aperture-coupled dual-mode patch resonators (AC-DMPRs)-based periodic element to realize single- and dual-band high-order bandpass frequency selective surfaces (FSSs). Initially, a single patch resonator (PR) loaded with two sets of shorting pins is theoretically studied by using the characteristic mode analysis (CMA) method and by applying periodic boundary conditions, respectively. The results demonstrate that the radiation pattern and resonant frequency of TM00 mode in the PR can be effectively reshaped and controlled by the shorting pins, so that the TM00 and TM01 modes can be simultaneously excited under the normal incidence of a plane wave. As such, the single-mode PR is transformed into a DMPR. Moreover, such DMPRs are arranged in a back-to-back manner with coupling apertures etched on the common middle metallic layer to form an AC-DMPR-based bandpass FSS element. By reasonably reallocating the resonant frequencies of these two resonant modes and etching different apertures to provide magnetic and/or electric couplings in the AC-DMPR, single- and dual-band high-order bandpass FSSs can be conveniently and flexibly constructed, respectively. Finally, the conceptual designs are validated by measurements.

Broadband and compact folded substrate integrated waveguide phase shifter and its application to 180° directional coupler

Abstract In this paper, a broadband, low insertion loss, and compact folded substrate integrated waveguide (FSIW) phase shifter is proposed for the first time. By loading the complementary split-ring resonators (CSRRs) on the middle metal layer of the FSIW, a closed-type slow-wave transmission line (TL) is obtained, which can provide a wideband phase shift (39%) compared with the equal-length fast-wave one. The enclosed structure of the CSRR-loaded FSIW prevents the CSRRs from radiation as suffered in the previous reported CSRR-loaded TLs, resulting in a low insertion loss. This feature greatly reduces the amplitude imbalance between the main line and the reference line of the phase shifter. In addition, no transition structure is required between the FSIWs with and without CSRRs for broadband impedance matching, which makes the phase shifter more compact and easier to integrate with other FSIW devices. To validate the performance of the proposed phase shifter and to illustrate its ease integration, a novel FSIW 180° directional coupler that consists of an FSIW 90° coupler and an FSIW 90° phase shifter is designed, fabricated, and measured. The measured results agree well with the simulated data.

Electronically Controlled Fixed-Frequency Beam-Scanning Periodic Leaky-Wave Antenna With Positive-Order-Harmonic Radiations

An electronically controlled fixed-frequency beam-scanning periodic leaky-wave antenna operating in a millimeter-wave band is presented in this letter. An air-filled gap waveguide (GW) base is employed as a millimeter-wave excitation thanks to its low-loss property. Totally, 60 patches in a staggered two-row arrangement are introduced as the radiating elements, which get energies from the GW through longitudinal slots etched on the middle metal layer, and this produces reverse phases in the two rows under a TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sub> -mode excitation. Then, a method by constructing an equivalent phase constant is developed in this letter, and positive-order-harmonic radiation is used to analyze the radiation property. By introducing the period-reconfigurable method, a fixed-frequency beam-scanning performance is achieved. In addition, the developed antenna is fabricated and experiments have been implemented. A beam-scanning range of 70° from −35° to 35° is realized using the positive-order-harmonic radiations at 29 GHz, and the measured peak gain arrives at 16.5 dBi. The design shows possible applications in millimeter-wave communications.

A design of broadband bandpass frequency selective surface

AbstractIn this paper, a broadband frequency selective surface (FSS) based on a multilayer coupling cascade is presented. The overall structure consists of three metallic layers and two dielectric substrates. In addition, a crosspatch terminated with an E‐shaped structure and a gradient cross structure with a slot is introduced in the middle metallic layer to control the transmission zero and extent of the current path, respectively. The unit cell periodicity is about 0.27 , and the overall thickness of the dielectric layer is about 0.087 . Prototypes of the proposed FSS are designed and simulated, and an equivalent circuit model is developed to explain the mechanism further. Finally, the FSS prototype works at the center frequency of 12.2 GHz with a relative −0.5 dB bandwidth of 70% and a relative −3dB bandwidth of 104%. The frequency responses are relatively stable with the variation of incidence angles from 0° to 60°.

High-power impulse magnetron sputter deposition for enhanced optical transmittance and electrical conductivity of flexible coating

A transparent conductive material, mostly transparent conductive oxide (TCO), is essential and indispensable for flexible electronics. Different from the conventional, single-layered TCO, multilayered oxide/metal/oxide (OMO) structures have been investigated as a promising alternative. The metal layer serves to reduce the electrical resistance of the oxides and the transparency is enhanced by suppressing the reflection from middle metal layer and substrate. Meanwhile, due to the limited temperature tolerance of the flexible polymeric substances, high-power impulse magnetron sputtering technique has been used to deposit the OMO structures at a substrate temperature lower than 70 °C. Two different OMO multilayered structures, including ZnO/Ag/ZnO and ZnO/Cu/ZnO, are deposited on polyethylene naphthalate (PEN) and polyethylene terephthalate (PET), and soda lime glass. The effects of layer thickness and metal type on the transmission and resistivity of the obtained OMO structures are investigated. The correlation between OMO structure characteristics and the resulting photoelectric properties are also studied. A 35-nm ZnO/20-nm Ag/30-nm ZnO having excellent resistivity of 6.2 × 10−5 Ωcm (7.2 Ωsq−1) and transmittance of 87.7% is demonstrated. Furthermore, after 3000 bending cycles, the multilayered OMOs on PET and PEN retain their superior electrical properties, exhibiting resistivity of 3.8 × 10−4 and 1.3 × 10−4 Ωcm, respectively.

Miniaturized Band Pass Filter Design Using Half Mode Substrate Integrated Coaxial Resonators.

The contribution of this work is to propose a half-mode substrate integrated coaxial resonator (HMSICR) and its application in bandpass filter (BPF) design. The proposed HMSICR is formed by evenly bisecting a square substrate integrated coaxial resonator (SICR), which is a cavity composed of two dielectric substrates and three metal layers. The SICR’s sidewalls are mimicked by periodically spaced thru-via arrays, and a circular patch is embedded in the middle metal layer of the SICR with the patch shorted to the cavity’s bottom wall by a circular array of blind vias. This HMSICR can drastically lower the cavity’s resonance frequency. The achieved frequency reduction rate of the proposed HMSICR, as compared with that of its conventional substrate integrated waveguide (SIW) cavity counterpart, reaches 70%. A sample four-HMSICR BPF is built for the circuit verification measurement. To further reduce the sample filter’s area, the composing HMSICRs are vertically stacked in a back-to-back configuration. We believe that its obtained size-reduction rate reaches the highest record.

Implementation of Magnetoelectric Dipoles in Metasurfaces for 5G Applications

The well-known magnetoelectric dipole (ME-dipole) has huge adoption in antenna designs. In this paper, we manage to implement ME-dipoles in metasurfaces. The unit cell of an ME-dipole metasurface consists of a cross slot etched on the middle metal layer and an ME-dipole loaded on each side of the middle metal layer. The unit cell of an ME-dipole metasurface is designed based on the antenna theory, i.e., one ME-dipole works as a receiving antenna while the other ME-dipole works as a transmitting antenna. The metasurface is then formed by arraying these unit cells in a periodic grid with optimal cell size. Three ME-dipole metasurfaces, including a frequency selective surface (FSS), a polarizer, and a transmitarray, are presented to show the potential of the proposed metasurface design method. The proposed concept and the design method are validated using simulation as well as experiments.

Dual-Band Miniaturized Linear-to-Circular Metasurface Polarization Converter With Wideband and Wide-Angle Axial Ratio

A dual-band miniaturized linear-to-circular polarization converter (LCPC) metasurface with wideband and wide-angle axial ratio (AR) is proposed and demonstrated. The metasurface is formed with periodic arrays of unit cells. The unit cells consist of three metallic layers separated by two substrates. The top and bottom metallic layers contain the identical cells with two metal strips and an “I”-type strip with four stubs for <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$y$ </tex-math></inline-formula> -polarization each. The middle metallic layer comprises an infinitely long metal strip and two “I”-type strips for <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$x$ </tex-math></inline-formula> -polarization. The LCPC performs a wideband response in both operating bands with the wide passbands generated by the orthogonal “I”-type strips. Prototyped <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$K$ </tex-math></inline-formula> -/ <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Ka</i> -band design shows that the simulated/measured AR remains below 3 dB over the lower bandwidth of 15–21.2 GHz (34.3%)/16.3–21.1 GHz (25.7%) and higher bandwidth of 27–30.3 GHz (11.5%)/27–29.8 GHz (9.9%) under normal incidence in <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$y-{z}$ </tex-math></inline-formula> plane, respectively. For a 45° incidence, the measured AR still achieved the 3 dB bandwidth of 33.7%/9.4% in both the bands. The study shows that by virtue of orthogonal structures placed at different layers, the element size and the cross-polarization level are suppressed by 65% and 10 dB, respectively, compared to the previous work. Furthermore, the LCPC with the miniaturized elements shows wide-angle response in both the bands.

Balanced multiple‐layer dual‐mode substrate integrated waveguide filters with controllable finite‐transmission zeros

This paper proposes three balanced multiple-layer dual-mode substrate integrated waveguide (SIW) bandpass filters. The first balanced filter has two substrate layers, and two pairs of balanced feeding ports are located on the upper substrate layer. The lower and upper dual-mode SIW cavities are coupled by two crossed slots in the middle metal layer. The second balanced filter has two substrate layers, and two pairs of balanced feeding ports locate parallelly on the upper and lower substrate layers, respectively. The third balanced filter has three substrate layers, and two pairs of balanced feeding ports locate vertically on the upper and lower substrate layers, respectively. The proposed three balanced filters can produce three, two and one finite-transmission zeros (FTZs), respectively. Characteristics of the proposed multiple-layer SIW filters with controllable FTZs' locations are analysed in detail. For the demonstration, some design examples with the centre frequency of 7.5 GHz and bandwidth of 240 MHz are presented, and three design examples are fabricated to verify the performance of the proposed balanced filters. The measured results agree well with simulated ones.

Cu-based tri-metallic nanoparticles with noble metals (Ag, Pd, and Ir) and their catalytic activities for hydrogen generation

The growth of simple and cost effective heterogeneous catalysts for the release of hydrogen is the key technological challenge for the fuel-cell based hydrogen economy. Stepwise metal displacement plating method was used for the fabrication of Cu0-based nanoparticles, Cu–Ag–Ir, Cu–Pd–Ir, and Cu–Ag–Pd to generate hydrogen from hydrazine hydrogen storage material. The preliminary indications of CuNPs production were the appearance of red-chocolate color with NaBH4, sodium dodecyl sulfate (SDS) under light emitting diode (LED) irradiation. Ag and Pd were deposited on the surface of Cu0 by rapid reduction with NaBH4 in SDS. Catalytic activity of trimetallic (Cu–Pd–Ir, Cu–Ag–Ir, Cu–Ag–Pd)) were higher than that of bimetallic (Cu–Ag, Cu–Ir, and Cu–Pd) due to the synergistic effect and electron interactions between the three metals. The catalytic performance of these materials depends on the structure of outer, and middle metal layers over a Cu inner metal. The nessler's reagent solution was employed to trap ammonia formation along with evolution of hydrogen generation. Cu25–Pd25–Ir50 exhibited the superior catalytic activity, with rate constant of 5.6 × 10−4 s−1 at 303 K, activation energy of 32 kJ/mol, activation enthalpy of 30 kJ/mol, and turn over frequency of 350 h−1.

Preparation and tribological behavior of polytetrafluoroethylene/metal mesh composites with sandwich structure

AbstractPolytetrafluoroethylene (PTFE) owns an excellent self‐lubricating performance, but its wear rate is very high due to the large‐scale spalling of the matrix in the friction. In this paper, A new kind of PTFE composites with sandwich structure was prepared by layer‐press technology, whose middle layer is filled with metal mesh. The influence of the mesh structure and mesh density of middle metal layer on tribological properties of composites were researched in detail. The results revealled that the metal mesh located in the composites can efficiently prevent the large‐scale spalling of PTFE, which induces the sample of PTFE/500# plain woven dutch metal mesh (PTFE‐500#PWD) to have a lower wear rate (9 × 10−5 mm3/Nm) and COF (0.106) under the fixed experimental condition. The prepared PTFE/metal mesh composites reveal excellent anti‐friction and anti‐wear performance, which can be used to fabricate a new kind of self‐lubricating materials.

Штамповая оснастка и инструмент для изготовления трехслойных плоских кольцевых деталей с композитными материалами

The results of designing die equipment and special tool through separate die operations for manufacturing sandwich flat ring parts with the middle base metal layer and periphery elastic layers with increased composite thickness are shown. Efficient geometrical dimensions and a tool shape ensuring qualitative manufacturing parts mentioned and extension of technological potentialities of separating operations for their manufacturing, in particular, for design options with the increased thickness of periphery elastic composite layers are optimized experimentally.

Single- and Dual-Band High-Order Bandpass Frequency Selective Surfaces Based on Aperture-Coupled Dual-Mode Patch Resonators

In this article, a class of bandpass frequency selective surfaces (FSSs) based on aperture-coupled dual-mode patch resonators (AC-DMPRs) are proposed to achieve single- and dual-band high-order filtering responses with low profiles. Initially, a basic resonator of a square patch with diagonal corner truncations is theoretically investigated so as to demonstrate that two orthogonal modes can be simultaneously excited in a single patch resonator. Then, to eliminate the cross-polarized reflection caused by the orthogonal modes, a composite resonator, including four of such corner-truncated patches with 90° rotation between each two adjacent patches, is constructed and analyzed. Furthermore, by arranging two of such composite resonators in a back-to-back manner through coupling apertures on the middle metallic layer, an FSS element of three-layer AC-DMPR is formed. Compared with traditional aperture-coupled patch resonators (AC-PRs), the resonant modes of AC-DMPR are increased twice, thus giving more design flexibility to achieve high-order performance. To validate the design concept, a single-band fourth-order bandpass FSS is designed by introducing magnetic couplings in the AC-DMPRs. Moreover, dual-band second-order bandpass FSSs with magnetic and/or electric couplings in the AC-DMPRs are also designed. Based on the even- and odd-mode analysis method, equivalent circuit models are established to explain the operating principles of the proposed structures. Finally, the designed FSSs are fabricated and measured. Good agreement between the measured and simulated results well validates the conceptual designs.

Dichroic Sb2O3/Ag/Sb2O3 Electrodes for Colorful Semitransparent Organic Solar Cells

The pace of advancement and increasing power conversion efficiencies (PCEs) have provided the possibility for organic solar cells (OSCs) to be commercialized in a variety of applications, including semitransparent photovoltaics. The application of dielectric–metal–dielectric (DMD) transparent electrodes to OSCs is an effective way to achieve semitransparent OSCs with different colors. Herein, a DMD multilayer structure based on two Sb2O3 layers and silver (Ag) thin films as the top electrode is introduced. An ultrathin Sb2O3 layer is deposited between the electron transport layer and the Ag film as a bottom layer for the Sb2O3/Ag/Sb2O3 electrode; this layer inhibits Ag atom diffusion and aggregation, which leads to uniform formation of ultrathin Ag films. The thickness of the middle metal layer influences fill factor and short‐circuit current density values, which correlate well with device resistance and light reflection. For the top Sb2O3 layer, the thickness allows the selective transmittance of specific wavelengths of visible light while reflecting wavelengths that are not transmitted, creating a dichroic effect. OSCs are successfully fabricated using three kinds of colorful active layers in conjunction with Sb2O3/Ag/Sb2O3 electrodes, resulting in vividly colored devices with PCE of 6.33–7.88% and average visible transmittances of 23–30%.

Broadband Terahertz Near-Perfect Absorbers.

Broadband terahertz (THz) absorbers are highly desired in detection, modulation, receiving, and imaging devices. We report the design and successful implementation of a novel broadband THz metasurface with a near-perfect absorption. Different from the traditional metal/dielectric/metal three-layer structures, the as-designed THz absorber has one more metal layer and a dielectric spacer on top, both of which are 200 nm thick. Although the total thickness increased by ∼7%, the near-perfect THz absorption band significantly broadened by 4×, achieving a broadband absorption of 270 GHz. Broadband, polarization-insensitive, and near-perfect THz absorptions were also observed over wide incident angles in these meta-absorbers, where the electric field and power loss were mainly concentrated in the additional thin dielectric layer. Such a broadband THz absorption was achieved through electromagnetic coupling between the top and middle metal layers and the resultant overlapping of the resonance frequencies. This strategy can be adapted to other spectrum-shaping devices.

Compact single‐ and dual‐band bandpass filters with controllable transmission zeros using dual‐layer dual‐mode loop resonators

An unbalanced microstrip bandpass filter (BPF) in dual-extended doublet topology with source-load (S-L) coupling is first presented and researched based on dual-layer capacitive-loaded dual-mode loop resonators. The input and output ports are located on the upper substrate layer. The lower dual-mode loop resonator is coupled to the upper loop resonator using four coupling apertures in the middle metal layer. Single- and dual-band responses with four controllable finite-transmission zeros (FTZs) are analysed. Then, a balanced BPF in dual-extended doublet topology without S-L coupling on the basics of the proposed unbalanced filter is presented and researched. Single- and dual-band differential mode responses with three controllable FTZs can be realised with good common mode suppression. Some design examples are provided to illustrate the performances of the realised single- and dual-band unbalanced and balanced filters with controllable FTZs. The measured results agree well with simulated ones.

Miniaturised wideband antenna with low profile based on dual‐layer metasurface

A novel miniaturised wideband antenna based on dual-layer metasurface (MS) is proposed in this study. It is composed of three metallic and two substrate layers. The top metallic layer is the MS whose unit is a square patch etched four interlaced quarter arc-shaped slots (PQAS). The middle metallic layer is a circular ring patch. The bottom metallic layer is the MS formed by the square metal ring (SMR). The top MS with PQAS and the bottom MS with SMR are combined which serve as a radiator and ground plane of the antenna directly, not a reflector. Thus, avoiding air layer, a low profile of 0.014 λ 0 (λ 0 is the guided wavelength at 2.57 GHz) is realised. Meanwhile, the impedance bandwidth and gain of the antenna are improved. The measured results show that the −10-dB impedance bandwidth of the proposed MS antenna is from 2.57 to 4.12 GHz (the relative bandwidth is 46.3%). Furthermore, the maximum gain reaches 4.17 dBi.