Experimental And Simulation Study On Vibration And Noise Of Foam-Filled Reinforced Sandwich Panels

Noise problems are prevalent in living and working environments and are regarded as the second largest environmental problem after air pollution.Reinforced sandwich panel structures are commonly used in vehicles,ships,aerospace and other fields,and their sound vibration characteristics are widely valued.The introduction of porous materials into reinfor ced sandwich panel structures can play a role in reducing structural vibration and lowering the radiated sound pressure level,but it also increases the complexity of the mechanical and acoustic response of such reinforced composite sandwich panels.Theref ore,this paper takes polyurethane foam-filled reinforced sandwich panel as the research object,and investigates the factors affecting the structural modal and acoustic radiation performance in the frequency band of 1-2000 Hz through a combination of experiment and simulation,and obtains the influence of foam parameters,structural parameters,mechanical parameters and other factors on the acoustic vibration characteristics of foam-filled reinforced sandwich panel.The effect of foam parameters,structural parameters and mechanical parameters on the sound vibration characteristics of foam-filled reinforced sandwich panels was obtained.The experimental results show that the influence of polyurethane foam filling on the modal frequency of reinforced sandwich panel in the frequency band of140-800 Hz is large,but the influence on other modes in the frequency band studied is relatively small,and the influence decreases with the increase of frequency.For the 140-800 Hz band,the filling of polyurethane foam tends to increase the bending modal frequency and decrease the torsional modal frequency of the large size reinforced sandwich panel.At the same time,the filling of polyurethane foam makes the peak acoustic radiation of the reinforced sandwich panel decrease significantly and has a tendency to shift to high frequency as a whole,especially,the acoustic radiation power of the large-size reinforced sandwich panel in the frequency band above 680 Hz decreases significantly as a whole.In addition,a finite element model consistent with the experiment was established,and the correctness of the finite element modeling was verified by compari ng and analyzing the experimental and simulation results.The simulation results show that the foam acoustic parameters and capacitance have a significant effect on the peak radiated sound power of the sandwich panel,while the effect on the peak frequency and the non-peak frequency band acoustic radiation performance is weak.The static flow resistivity and tortuosity have a large effect on the peak acoustic radiation performance.Among the remaining foam parameters,the reduction of characteristic thermal length and the increase of static flow resistivity and capacitance can improve the acoustic radiation performance of the panels.1-1000 Hz frequency band,the reduction of tortuosity and the increase of characteristic viscous length are beneficial to improve the acoustic radiation performance of the panels,while the 1000-2000 Hz frequency band shows the opposite pattern.In addition,the effect of porosity on the acoustic radiation performance is almost negligible.Structural changes have a large effect o n the acoustic radiation performance of the peak frequency and non-peak frequency bands of the plate.In the 1-500 Hz frequency band,the plate radiated sound power is only related to the plate surface density,the greater the plate surface density,the sma ller the plate radiated sound power.At the same time in the 500-2000 Hz non-peak frequency band,plate radiation sound power is mainly affected by the role of surface density,the law is similar to the 1-500 Hz band.Plate radiation sound power peak frequen cy and plate stiffness and surface density are related,the smaller the surface density of the plate,the greater the stiffness,the higher the peak frequency.In the case of constant surface density,the thicker the plate thickness at the force excitation,the greater the structural stiffness or the greater the difference between the two layers of plate thickness,the better the sound radiation performance of the plate.In addition,Poisson’s ratio has less influence on the radiated sound power of the plate.