The Experts below are selected from a list of 14574 Experts worldwide ranked by ideXlab platform

Meina Huang - One of the best experts on this subject based on the ideXlab platform.

  • the structure and performance of short glass fiber high density polyethylene polypropylene composite pipes extruded using a shearing drawing compound stress field
    Materials, 2019
    Co-Authors: Yi Yuan, Changdong Liu, Meina Huang
    Abstract:

    Glass fiber reinforced polyolefin composite materials have many advantages regarding their performance and have been widely used in many fields. However, there are few reports on the simultaneously bidirectional self-enhancement of glass fiber reinforced polyethylene/polypropylene composite pipe. To self-reinforce the pipe's circular and axial properties simultaneously, short glass fiber reinforced high-density polyethylene/polypropylene (SGF/HDPE/PP) pipes were extruded using a shearing-drawing two-dimensional compound stress field pipe-extrusion device. The effects of the rotating speed of the rotating shear sleeve on the orientation, heat behavior, microstructure, and tensile strength of the pipe were investigated in this paper. The microstructure was observed using scanning electron microscopy (SEM), and the Crystal diffraction was analyzed using a polyCrystalline X-ray diffractometer (WAXD), the heat behavior was measured using a differential scanning calorimeter (DSC), and the tensile strength was tested using a universal electronic tensile testing machine. The results showed that the shear induction effect induced by the shear rotating promoted the formation of the oriented structure of the Crystal Plate and SGFs along the circular and axial directions of the pipe simultaneously. Furthermore, it increased the Crystallinity of the system, and self-improved the pipe's circular and axial tensile strength at the same time.

  • The Structure and Performance of Short Glass Fiber/High-Density Polyethylene/Polypropylene Composite Pipes Extruded Using a Shearing–Drawing Compound Stress Field
    MDPI AG, 2019
    Co-Authors: Yi Yua, Changdong Liu, Meina Huang
    Abstract:

    Glass fiber reinforced polyolefin composite materials have many advantages regarding their performance and have been widely used in many fields. However, there are few reports on the simultaneously bidirectional self-enhancement of glass fiber reinforced polyethylene/polypropylene composite pipe. To self-reinforce the pipe’s circular and axial properties simultaneously, short glass fiber reinforced high-density polyethylene/polypropylene (SGF/HDPE/PP) pipes were extruded using a shearing–drawing two-dimensional compound stress field pipe-extrusion device. The effects of the rotating speed of the rotating shear sleeve on the orientation, heat behavior, microstructure, and tensile strength of the pipe were investigated in this paper. The microstructure was observed using scanning electron microscopy (SEM), and the Crystal diffraction was analyzed using a polyCrystalline X-ray diffractometer (WAXD), the heat behavior was measured using a differential scanning calorimeter (DSC), and the tensile strength was tested using a universal electronic tensile testing machine. The results showed that the shear induction effect induced by the shear rotating promoted the formation of the oriented structure of the Crystal Plate and SGFs along the circular and axial directions of the pipe simultaneously. Furthermore, it increased the Crystallinity of the system, and self-improved the pipe’s circular and axial tensile strength at the same time

Jun Liu - One of the best experts on this subject based on the ideXlab platform.

  • the slow zero order antisymmetric lamb mode in phononic Crystal Plates
    Ultrasonics, 2013
    Co-Authors: Jun Liu
    Abstract:

    In this paper, the group velocities of the zero order antisymmetric (A0) Lamb modes in a phononic Crystal Plate with single layer cylindrical holes parallel to the surface of the Plate were investigated theoretically. The results show that by increasing the filling fraction, the A0 mode can be efficiently slowed down and the group velocity of the A0 modes can be tuned from the positive to the negative referring to the phase velocity. Moreover, the zero group velocity of the A0 modes can be obtained with a given filling fraction. These results may be useful in designing acoustic devices. 2012 Elsevier B.V. All rights reserved.

  • the investigation of point defect modes of phononic Crystal for high q resonance
    Journal of Applied Physics, 2011
    Co-Authors: Jun Liu
    Abstract:

    Point defect cavity was constructed in a two-dimensional phononic Crystal Plate. It was excited by a small piezo chip in the cavity, and the vibrations of each point defect mode were detected by an optical interferometer. Point defect modes on 2D phononic Crystal Plate in vacuum, air, and with water loaded were investigated theoretically and experimentally. It is shown that the Q factors of the point defect modes are determined by inner attenuation, bandgap effects, and medium. The SSS mode (breathing mode) has highest Q factor in vacuum and air among nine modes thanks to low inner attenuation and low energy leakage. By selectively loading the PC with water on one side, the point defect modes with shear movement surfaces suffer lower attenuation and still have rather high Q factors. These conclusions will help to design a new kind of resonator or sensor.

  • the investigation of point defect modes of phononic Crystal for high q resonance
    International Conference on Solid-State Sensors Actuators and Microsystems, 2011
    Co-Authors: Jun Liu
    Abstract:

    Point defect cavity was constructed in a two-dimensional phononic Crystal Plate. It was excited by a small piezo chip in the cavity and the vibration of each point defect modes were detected by an optical interferometer. Point defect modes on 2D PC Plate in vacuum, air and loaded with water were investigated theoretically and experimentally to make clear of Q factors, which are affected by inner attenuation, band gap effects and medium. The way to get high Q resonance has been found. It helps to design a new kind of resonator or sensor.

B Djafarirouhani - One of the best experts on this subject based on the ideXlab platform.

  • rainbow guiding of the lowest order antisymmetric lamb mode in phononic Crystal Plate
    Science China-technological Sciences, 2019
    Co-Authors: Jinfeng Zhao, B Djafarirouhani, Bernard Bonello, Yongdong Pan, Weitao Yuan, Zheng Zhong
    Abstract:

    The modern acoustic circuits have experienced significant progress with the development of artificial structures, including phononic Crystals, metamaterials or metasurfaces. Among the most intensive topics, the reconfigurable acoustic guides are achieved through several mechanisms. In this work, we report on the rainbow guiding for the lowest-order antisymmetric Lamb (A0) mode in a phononic Crystal Plate, where the linear waveguides are constituted by erecting aligned pillars either solid or hollow. We show both numerically and experimentally that the whispering gallery modes (WGMs) in the hollow pillars can be generated by the defect mode that propagates in the waveguide. Then, the reemission of A0 mode by the WGMs to the outer lateral areas can lead to spatial control of frequency selective wave guidance called “rainbow guiding”. Our approach allows for an accurate control of the wave guiding and facilitates the integration of waveguides within other devices in the acoustic circuits.

  • phononic Crystal Plate with hollow pillars actively controlled by fluid filling
    Crystals, 2016
    Co-Authors: Yabin Jin, Yan Pennec, Yongdong Pan, B Djafarirouhani
    Abstract:

    We investigate theoretically the properties of phononic Crystal Plates with hollow pillars. Such Crystals can exhibit confined whispering gallery modes around the hollow parts of the pillars whose localization can be increased by separating the pillar from the Plate by a full cylinder. We discuss the behaviors of these modes and their potential applications in guiding and filtering. Filling the hollow parts with a fluid gives rise to new localized modes, which depend on the physical properties and height of the fluid. Thus, these modes can be actively controlled for the purpose of multichannel multiplexing. In particular, one can obtain localized modes associated with the compressional vibrations of the fluid along its height. They can be used for the purpose of sensing the acoustic properties of the fluid or their variations with temperature.

  • tunable waveguide and cavity in a phononic Crystal Plate by controlling whispering gallery modes in hollow pillars
    Physical Review B, 2016
    Co-Authors: Yan Pennec, Yabin Jin, Nicolas Fernez, Bernard Bonello, Rayisa P Moiseyenko, Stephanie Hemon, Yongdong Pan, B Djafarirouhani
    Abstract:

    We investigate the properties of a phononic Crystal Plate with hollow pillars and introduce the existence of whispering-gallery modes (WGMs). We show that by tuning the inner radius of the hollow pillar, these modes can merge inside both Bragg and low frequency band gaps, deserving phononic Crystal and acoustic metamaterial applications. These modes can be used as narrow pass bands for which the quality factor can be greatly enhanced by the introduction of an additional cylinder between the hollow cylinder and the Plate. We discuss some functionalities of these confined WGM in both Bragg and low frequency gaps for wavelength division in multiplexer devices using heteroradii pillars introduced into waveguide and cavity structures.

  • absolute forbidden bands and waveguiding in two dimensional phononic Crystal Plates
    Physical Review B, 2008
    Co-Authors: J O Vasseur, B Djafarirouhani, Yan Pennec, P A Deymier, A C Hladkyhennion
    Abstract:

    We introduce a supercell plane wave expansion (SC-PWE) method for the calculation of elastic band structures of two-dimensional phononic Crystal Plates. We compute the band structure of solid-solid and air-solid two-dimensional phononic Crystal Plates. The air is modeled as a low impedance medium (LIM) with very low density and very high velocities of sound. We investigate the influence of the constituent materials, of the Plate thickness, and of the geometry of the array on the band structure. We establish the range of validity of the SC-PWE method in terms of the rate of convergence with respect to the number of plane waves and contrast in physical properties of the matrix and inclusion materials. We show that for high contrast solid-solid phononic Crystal Plates, our SC-PWE method, as other PWE-based methods introduced to date, suffers from convergence difficulties. In the case of air (modeled as the LIM) holes-solid Plates, we demonstrate that the SC-PWE method leads to fast convergence for a wide range of values of solid physical properties. With these constituent materials, we find that the largest absolute forbidden bands occur in the band structure of the phononic Crystal Plate provided the thickness of the Plate is of the order of magnitude of the periodicity of the array of inclusions. We demonstrate the existence of guided modes in an air-silicon phononic Crystal Plate containing a linear defect.

  • waveguiding in two dimensional piezoelectric phononic Crystal Plates
    Journal of Applied Physics, 2007
    Co-Authors: J O Vasseur, B Djafarirouhani, Yan Pennec, A C Hladkyhennion, F Duval, B Dubus, P A Deymier
    Abstract:

    We investigate the possibility of designing phononic Crystal-based devices for telecommunication applications using materials commonly employed in microfabrication. We focus our attention on a phononic Crystal made of a square array of cylindrical holes drilled in an active piezoelectric PZT5A matrix. Two different structures are considered, namely, a freestanding phononic Crystal Plate and a Plate deposited on a silicon substrate. The geometrical characteristics of the phononic Crystal Plates (lattice parameter and thickness) were chosen to ensure the existence of an absolute band gap around 1.5GHz; a common frequency in radio frequency telecommunications. Computations of the dispersion curves of these active structures were conducted with the help of the finite element method. We demonstrate the existence of absolute band gaps in the band structure of the phononic Crystal Plates and, then, the possibility of guided modes inside a linear defect created by removing one row of air holes in the phononic Crystal. In the case of the supported phononic Crystal Plates, we show the existence of an absolute forbidden band in the Plate modes when the thickness of the substrate significantly exceeds the Plate thickness. We discuss the conditions to realize waveguiding through a linear defect inside the supported Plate. The present work provides evidences that phononic Crystal properties can be integrated with existing silicon based microdevice technology

Haosu Luo - One of the best experts on this subject based on the ideXlab platform.

  • optimizing dual piezoelectric layer ultrasonic transducer via systematic analysis
    Sensors and Actuators A-physical, 2020
    Co-Authors: Sixing Liu, Zhang Zhang, Junjie Xiao, Xian Wang, Haosu Luo
    Abstract:

    Abstract In order to optimize the center frequency and bandwidth characteristics of the dual-piezoelectric-layer ultrasonic transducers, an investigation was conducted to find the optimal connection and material combination methods between piezoelectric layers for a dual-piezoelectric-layer structure utilizing systematic comparison and analysis. Finite element analysis (FEA) simulation results show that among all the connection methods, the one based on inversion layer technique exhibits the greatest performance. The simulation results also show that when a PMNT single Crystal Plate is used as the first piezoelectric layer and a PZT ceramic Plate is used as the second piezoelectric layer with a thickness ratio of 7.5:2.5, the transducer presents about 16 % higher center frequency and 50 % broader −6 dB bandwidth as well as a shorter −6 dB lateral beam width compared with a conventional single-piezoelectric-layer transducer. The measurement results prove that the transducer with the proposed structure exhibits the greatest performance, which obtains about 42 % higher center frequency and 10.4 % broader −6 dB bandwidth compared with a conventional transducer. In the meanwhile, the proposed transducer has the shortest pulse length as well. These characteristics are conducive to improving the lateral and axial resolution of ultrasound imaging.

  • magnetoelectric effect from mechanically mediated torsional magnetic force effect in ndfeb magnets and shear piezoelectric effect in 0 7pb mg1 3nb2 3 o3 0 3pbtio3 single Crystal
    Applied Physics Letters, 2008
    Co-Authors: Yaojin Wang, Helen Lai Wa Chan, Xiangyong Zhao, Haosu Luo
    Abstract:

    We experimentally and theoretically report the magnetoelectric effect in a composite made by sandwiching one shear mode 0.7PbMg1∕3Nb2∕3O3–0.3PbTiO3 (PMN-PT) piezoelectric single Crystal Plate between two longitudinally magnetized NdFeB permanent magnet bars along the length direction of the PMN-PT Plate. The magnetoelectric effect originates from the mechanically mediated product effect of the torsional magnetic force effect in the NdFeB bars and the shear piezoelectric effect in the PMN-PT Plate. The composite exhibits a magnetoelectric voltage coefficient of ∼32.7mV∕cmOe with a flat frequency response in the measured range of 0.1–30kHz. The induced magnetoelectric voltage shows a good linear relationship to the applied ac magnetic field with amplitude varying from 10−7to10−3T. Other distinct features include no need to have a magnetostrictive phase, low Joule heating loss, and high scale-down capability. These suggest promising applications of the torsional-shear mode composite in power-free magnetic fi...

Yi Yuan - One of the best experts on this subject based on the ideXlab platform.

  • the structure and performance of short glass fiber high density polyethylene polypropylene composite pipes extruded using a shearing drawing compound stress field
    Materials, 2019
    Co-Authors: Yi Yuan, Changdong Liu, Meina Huang
    Abstract:

    Glass fiber reinforced polyolefin composite materials have many advantages regarding their performance and have been widely used in many fields. However, there are few reports on the simultaneously bidirectional self-enhancement of glass fiber reinforced polyethylene/polypropylene composite pipe. To self-reinforce the pipe's circular and axial properties simultaneously, short glass fiber reinforced high-density polyethylene/polypropylene (SGF/HDPE/PP) pipes were extruded using a shearing-drawing two-dimensional compound stress field pipe-extrusion device. The effects of the rotating speed of the rotating shear sleeve on the orientation, heat behavior, microstructure, and tensile strength of the pipe were investigated in this paper. The microstructure was observed using scanning electron microscopy (SEM), and the Crystal diffraction was analyzed using a polyCrystalline X-ray diffractometer (WAXD), the heat behavior was measured using a differential scanning calorimeter (DSC), and the tensile strength was tested using a universal electronic tensile testing machine. The results showed that the shear induction effect induced by the shear rotating promoted the formation of the oriented structure of the Crystal Plate and SGFs along the circular and axial directions of the pipe simultaneously. Furthermore, it increased the Crystallinity of the system, and self-improved the pipe's circular and axial tensile strength at the same time.