Asymmetrical Y-shaped and Y-ring-shaped frequency selective fabrics(FSFs) were proposed in this paper. They were prepared by computer engraving technology and tested in the anechoic chamber by using the free-space met...Asymmetrical Y-shaped and Y-ring-shaped frequency selective fabrics(FSFs) were proposed in this paper. They were prepared by computer engraving technology and tested in the anechoic chamber by using the free-space method. The test results of representative samples show that the resonance frequencies and the resonance peak or valley values in two polarization modes are not completely identical but the differentials are small, indicating that the influences of polarization modes are not significant. The transmission coefficient curves of Y-shaped and Y-ring-shaped FSFs with various size parameters are obviously different. For instance, as the unit size D increases by 4.0 mm, the resonance frequencies of patch FSFs decrease by 1.92 GHz and the resonance valleys increase by 12.32 dB. Different size parameters have dissimilar effects on the transmission characteristics and the corresponding influence laws should be analyzed concretely. The work could provide reference for the structural design and characteristics analysis of other FSFs.展开更多
Flax and jute fabrics are adopted to reinforce epoxy matrix composites in order to explore the feasibility of replacing wood in percussion instruments.The fabrics are treated with alkaline solutions to improve interfa...Flax and jute fabrics are adopted to reinforce epoxy matrix composites in order to explore the feasibility of replacing wood in percussion instruments.The fabrics are treated with alkaline solutions to improve interfacial adhesion between fibers and epoxy.The composites are fabricated using the hand-lay and vacuum assisted resin infusion process.Acoustic dynamic moduli,acoustic radiation damping coefficients,and acoustic impedances of the composites are tested and compared with those of the wood regularly used to make the percussion instruments.It is found that the acoustic properties of the composites are within the range of those of the wood,indicating that it could be feasible to replace the wood with natural cellulose fiber reinforced composites in percussion instrument production.展开更多
基金Natural Science Foundation of Fujian Province,China (Nos.2019J01740 and 2021J05187)Education and Scientific Research Foundation for Middle-Aged and Young Scientist of Fujian Province,China (Nos.JT180377 and JAT190527)+2 种基金Quanzhou City Science&Technology Program of China (Nos.2018K002 and 2020C039R)Startup Foundation for Doctors of Quanzhou Normal University,China (Nos.H18024 and H18028)Innovation and Entrepreneurship Training Project for College Students,China (Nos.S201910399036 and 202010399113)。
文摘Asymmetrical Y-shaped and Y-ring-shaped frequency selective fabrics(FSFs) were proposed in this paper. They were prepared by computer engraving technology and tested in the anechoic chamber by using the free-space method. The test results of representative samples show that the resonance frequencies and the resonance peak or valley values in two polarization modes are not completely identical but the differentials are small, indicating that the influences of polarization modes are not significant. The transmission coefficient curves of Y-shaped and Y-ring-shaped FSFs with various size parameters are obviously different. For instance, as the unit size D increases by 4.0 mm, the resonance frequencies of patch FSFs decrease by 1.92 GHz and the resonance valleys increase by 12.32 dB. Different size parameters have dissimilar effects on the transmission characteristics and the corresponding influence laws should be analyzed concretely. The work could provide reference for the structural design and characteristics analysis of other FSFs.
基金National Natural Science Foundation of China(No.51803108)Natural Science Foundation of Fujian Province,China(Nos.2019J01740,2019J05106)+2 种基金Quanzhou City Science&Technology Program,China(Nos.2016Z071,2018K002,2018G011)Startup Foundation for Doctors of Quanzhou Normal University,China(No.H18028)Science and Technology Program of Quanzhou Normal University,China(No.2013KJ04)。
文摘Flax and jute fabrics are adopted to reinforce epoxy matrix composites in order to explore the feasibility of replacing wood in percussion instruments.The fabrics are treated with alkaline solutions to improve interfacial adhesion between fibers and epoxy.The composites are fabricated using the hand-lay and vacuum assisted resin infusion process.Acoustic dynamic moduli,acoustic radiation damping coefficients,and acoustic impedances of the composites are tested and compared with those of the wood regularly used to make the percussion instruments.It is found that the acoustic properties of the composites are within the range of those of the wood,indicating that it could be feasible to replace the wood with natural cellulose fiber reinforced composites in percussion instrument production.
