Research On Wave Manipulation Characteristic On Phononic Crystal Based On Acoustic Black Hole

The acoustic black hole structure is a kind of local resonant phonon crystal.Compared with the traditional phonon crystal,its obvious advantage is that it can show some excellent control characteristics of wave propagation only by geometric clipping.In addition,phononic crystals based on acoustic black holes have great engineering application prospects in the fields of vibration and noise control,acoustic energy collection and acoustic manipulation.In this paper,the phonon crystal plate embedded in acoustic black hole array is taken as the research object,and the finite element simulation analysis model is established to study its manipulation characteristics of sound waves at a certain frequency.At the same time,the influence of acoustic black holes with different geometric parameters on the energy band structure of crystal cells is explored,so as to reveal the feasibility of its engineering application.The main content of this paper is as follows:(1)The beam model and plate model of acoustic black hole are established by using the theory of acoustic black hole.The dynamic response of acoustic black hole beam is calculated by semi-analytical method,and the reflection coefficient of acoustic black hole beam with different damping materials is calculated by structural impedance method.(2)Acoustic black hole geometry parameters of the model is established,and studies the geometric parameters on the acoustic black crystal cell,the influence of band structure including thickness and wedge cross section bending truncation index two main parameters,the calculation results show that the above parameters change mainly reflects in the intersection of different model,the influence of band structure for acoustic black hole cell will not produce significant changes;(3)For the crystal cell model of acoustic black hole,finite element method was used to calculate the frequency contour,through which the group velocity variation rule of wave in the crystal cell could be obtained,so as to obtain the control rule of acoustic black hole structure on the wave propagation direction.The influence of different parameters on the frequency contour is calculated.The simulation results show that the flatter the cross section of the acoustic black hole cell is(the smaller the value is),the lower the characteristic frequency is.(4)The finite element model of phononic crystal plate based on acoustic black hole structure is established.The frequency domain response of acoustic black hole phonon crystal plate is calculated by taking the characteristic frequency of the frequency contour line as the excitation frequency(including point load,line load and plane load),and the collimation effect,focusing effect,negative refraction effect and double refraction effect are revealed.The feasibility of using the acoustic black hole structure as a phonon crystal plate cell to manipulate sound waves is verified.