Study On Sound Insulation Characteristics Of Composite Structure Based On Periodic Structure

There are a large number of scenes that need sound insulation in the fields of vehicle engineering,aviation engineering and ship engineering.Therefore,it is of great significance to study the sound insulation performance of composite plate structure with low surface density and high sound insulation.The periodic structure has the band gap characteristics of suppressing elastic wave transmission,and can effectively reduce the vibration and acoustic radiation of the structure in the band gap range.Therefore,the periodic composite plate structure has a good application prospect.This thesis mainly studies the sound insulation band gap characteristics and sound insulation performance of periodic composite plate structure,and analyzes the parameter influence law of sound insulation performance.In this thesis the research status of composite sound insulation structure and phononic crystal is reviewed in detail.The theoretical basis of composite sound insulation structure and the analysis method of structural energy band characteristics are introduced.The following work is mainly carried out :Experimental study on sound insulation performance of composite plate structure.Several groups of periodic damping composite plate structures were designed and processed,and the sound insulation performance was tested in the double reverberation chamber.The effects of parameters such as periodic shape,damping form,reinforcement form,reinforcement thickness and intermediate plate thickness on the sound insulation of the structure are studied respectively.The results show that both reinforcement and periodic damping can effectively improve the sound insulation performance of the composite plate structure.The periodic damping mainly acts in the 160-500 Hz frequency band,and the average sound insulation of the periodic damping composite plate is 1.3 d B higher than that of the full damping composite plate.The reinforcement mainly acts in the frequency range of 500-2000 Hz,and the average sound insulation of the stiffened composite plate is 2.7 d B higher than that of the unstiffened composite plate.Study on sound insulation performance of periodic damping composite plate structure.The analysis method of sound insulation performance of periodic damping composite plate structure is established and verified by experiments.The influence of periodic damping structure parameters and geometric parameters on the sound insulation performance of composite plate structure is studied.The results show that in the 160-500 Hz frequency band,the sound insulation of the periodic damping composite plate structure is better than that of the full damping composite plate structure,and the sound insulation performance of the composite plate structure with two-dimensional block damping is the best,which is 37.3 d B;the location and thickness of damping have little effect on the sound insulation performance of composite plate structure.In practical engineering,in order to save cost and reduce weight,periodic damping composite plate with thickness of 1mm and damping coverage of less than 50 % is usually used.In the frequency band of 200-500 Hz,with the increase of the lattice constant of periodic damping,the average sound insulation performance of the composite plate structure increases by 0.5d B on average.Study on band gap characteristics and sound insulation performance of locally resonant composite plate structure.By adding a mass block in the composite sound insulation board structure,a local resonance composite sound insulation structure is formed.The analysis method of sound insulation performance of locally resonant composite plate structure is established,and the influence of material parameters and geometric parameters on the band gap characteristics and sound insulation performance of locally resonant composite plate structure is studied.The results show that the band gap range of the locally resonant composite plate structure is 100-500 Hz,and the locally resonant composite sound insulation structure has good sound insulation performance in the band gap characteristic frequency range.The radius of the local oscillator has the greatest influence on the band gap characteristics and sound insulation performance of the structure.When the radius reaches0.09 m,the single-valued evaluation sound insulation of the structure is the largest,which is45.5 d B.With the increase of lattice constant,mass thickness and damping thickness,the initial frequency and cut-off frequency of the band gap move to low frequency.