Research On Vibration Reduction Characteristics And Structural Strengthening Of Acoustic Black Hole Plate

The acoustic black hole effect is to tailor the thickness of the beam or thin plate structure according to the law of power change,so that the bending wave at the tip of the structure drops to zero without reflection,so as to achieve the purpose of plate vibration control.Based on the acoustic black hole plate model,combined with the energy band structure theory in the frequency domain,this paper analyzes the influence of different parameters of the acoustic black hole on the vibration damping characteristics of the plate.In view of the structural weakening caused by acoustic black holes,a model of a plate with stiffeners was established,and the influence of stiffeners and their distribution on the damping characteristics and vibration transmission loss of acoustic black hole plates was studied.Finally,through the vibration control experiment,the effectiveness of the stiffener plate on the vibration damping and structural strengthening of the plate is verified.The full text of the study is as follows:1)Aiming at the damping characteristics of acoustic black holes,a finite element model is established,and the influence of acoustic black hole slope,cut-off thickness,distribution position and damping on the damping characteristics of the plate is analyzed in the frequency domain.Based on the phononic crystal theory,the energy band structure of a single acoustic black hole is calculated,and the transmission loss of the multi-period acoustic black hole in the forbidden band is analyzed.The research shows: in the damping characteristics,the smaller the cut-off thickness,the better the damping effect.The closer the acoustic black hole is to the excitation end,the better the vibration reduction effect.The smaller the slope in the low frequency range,the better the vibration reduction effect,and the opposite is in the high frequency range.From the perspective of the vibration transmission forbidden band: the more cycles there are,the more obvious the vibration reduction effect of the forbidden band.And at low frequencies below 2000 Hz,the smaller the cut-off thickness,the wider the band gap frequency range.In the frequency range above 2000 Hz,the greater the slope,the wider the band gap.2)Aiming at the structural weakening caused by acoustic black holes,a model of acoustic black holes with stiffeners is established.The influence of the width,number,distribution position of the stiffeners in the frequency domain and the arrangement of stiffeners in the multi-period black hole on the vibration damping characteristics and vibration transmission loss of the plate is analyzed.The research shows: the vibration damping effect is best when the stiffeners are evenly distributed in the plate.The greater the number of high-frequency stiffeners,the better the damping effect,while the low-frequency result is opposite.When the total width of the stiffeners is the same,the more the number of stiffeners,the better the high-frequency vibration damping effect.The addition of ribs in the multi-cell will weaken the forbidden band vibration damping effect,and the more the number of roots,the weaker the forbidden band vibration damping effect.3)A vibration control test platform was built,and the vibration damping characteristics of plates with different structures were experimentally studied.The experimental results show that the addition of stiffeners can effectively improve the weakening of structural stiffness and maintain a good vibration reduction effect.