Research On Structural Sound Transmission Based On Acoustic Black Hole

Vibration and noise control of structures has long been one of the important topics of interest to researchers.The vibration of the structure not only affects the normal operation of the mechanical equipment,but can even cause fatigue damage to the structure.The noise generated by the structure during the transmission of vibration also affects the environmental comfort of the staff.Research into the transmission of structural sound can help to find effective means of controlling it.Conventional wave resistive techniques play a large part in this,but they are also somewhat flawed.The Acoustic Black Hole(ABH),derived from the black hole concept and developed into a new wave-damping technology,is receiving more and more attention from researchers because of its simple structure,wide frequency and efficient suppression of structural vibration.Most of the current research on acoustic black holes focuses on beams or flat plates,but in practical applications,the phenomenon of plate to plate or beam to beam connection into a corner is more common.In this paper,we use a finite element approach to build individual corner coupling plates on COMSOL Multiphysics in combination with conventional wave dampening techniques,to study the vibration of the embedded acoustic black hole coupling plates and the uniform coupling plates in contrast,and to analyze the effect of the coupling plate corner on vibration transfer.First,the parameters of the acoustic black hole structure are investigated for each corner coupling plate of the embedded acoustic black hole structure,and the simulation results show that the increase of the central platform and truncation of the acoustic black hole and the decrease of the length of the acoustic black hole at frequencies below 1k Hz inhibit the transmission of vibrations from the structure to the downstream structure,but the opposite is true at frequencies above 1k Hz.At certain parameters of the acoustic black hole structure,an increase in the angle of rotation will lead to an increase in vibration transfer in the structure.Then,the results show that under the condition of line load to simulate plane bending wave incidence,the coupling plate of embedded acoustic black hole can realize the aggregation of transverse wave vibration energy in the high-frequency region compared with the uniform coupling plate,which can greatly reduce the vibration transmitted to the downstream structure,but the suppression effect on longitudinal wave transmission is not much different from that of the uniform coupling plate;The acoustic black hole structure with damping or blocking mass can well suppress the the transmission of the acoustic black hole coupling plate in the high frequency area to the downstream structure,the principle of which is to add damping in the acoustic black hole structure area to absorb the vibration of the structure,the other is to add blocking mass at the corner plate coupling to achieve the "blocking" of high frequency vibration;the acoustic black hole structure coupling plate with both blocking mass and damping can further suppress the vibration of the structure;in the analysis of the effect of point load,it is found that under point load excitation,the acoustic black hole structure also can achieve the vibration suppression effect as under line load.Finally,the frequency response under point excitation of the acoustic black hole coupled plate is verified by the experimental method,and the experimental results have the same curve trend as the simulation results,proving the feasibility of the thesis simulation calculation;at the same time,the additional damping of the acoustic black hole structure in the experiment makes the frequency response under point excitation is well suppressed.