Two-dimensional Phononic Crystal Band Gap Grid Regulatory Role

Arranged in two-dimensional iron/water square phononic crystal plate for the motherboard model, we analyze two-component grid plate, three-component grid plate as well as grid plate with defects on the motherboard acoustic permeability with finite difference time domain (FDTD), Details are as follows:1,The fill rate of the grid plate, grid plate relative to the location of the motherboard, the thickness of the grid plate, grid plate scatterers within the close-packed structure will affect the motherboard acoustic permeability. The grid plate scatterers within the close-packed structure than the fill rate of the grid plate, grid plate relative to the location of the motherboard, the gate plate itself, the thickness of factors should be large. Close-packed structure of the grid plate can greatly affect the motherboard sound permeability, and even high-frequency band gap; large filling ratio of the gate plate smaller filling ratio of the grid plate structure; three-tier grid plate than the single layer gate board.2,Two groups of structural grid plate, grid plate of the scattering body has a very soft material, usually lead to the motherboard with a band gap structure in the low frequency range; three groups cladding system, such as rubber (lead)/water, rubber (ironwill lead to low-frequency band gap)/water and rubber (air)/water and other ’hard’ core ’soft’ type of cladding grid plate, core column material of this type of system of scatterers is relatively small bandgap; three groupselement cladding systems such as lead (rubber)/water, iron (rubber)/water and air (rubber)/water and other ’soft’ core ’hard’ type of cladding grid plate, the outer layer of ’hard’ materials dominate the scattering effect of;’hard’ core ’soft’ veneer cladding and ’soft’ core ’hard’ cladding veneer mixed system, there will be a band gap of the stack effect, and little relationship with them before and after the order of the veneer combination.3,The thickness of the grid plate adjustment of the band gap of phononic crystals motherboards generally have enhanced the effect and this effect is related with the formation of the band gap principle. Among them, three sets of grid plate system with locally resonant structures, with the increase in the number of layers of the grid plate, the thickness increases, the low frequency range at the transmission rate will be gradually reduced, and tends to zero, low band gap wider; two sets of grid plate system, not consider the scattering process in case of loss of energy, the thickness of the grid plate on the motherboard band gap of little regulation.4,In the grid plate band gap of regulation due to the different defects and different defects on the motherboard. Two sets of rubber/water grid plate, a single line defect will be introduced to the defect mode may appear in the original motherboard broadband gap defect states, so that the original wide band gap broken into a number of small band gap; introduce more line defect, the original band the gap is even more broken, the transmittance irregular changes.Others, such as well-shaped defects, the V-shaped defects grid plate on the motherboard with the structure of, due to different defects showed incomplete rule changes. In general, the changes in the scale and size of defects and the band gap into a positive correlation.