Numerical Study On Acoustic Performance Of Cabin Plate Based On Standing Wave Tube Method

With the development of society,people pay more and more attention to the problem of noise pollution.In shipbuilding and shipping industry,how to reduce cabin noise and create a more comfortable and quieter environment for sailors to work and live in,has become a concern for researchers at home and abroad.Among them,the sound transmission loss,which is an important parameter to measure the effect of sound insulation of structures,is one of the focuses of research.How to get the sound transmission loss quickly and accurately,how to determine the factors affecting the measurement of the sound transmission loss of structures,to improve the sound transmission loss of plates,has become a hot research topic.The standing wave tube method is the main experimental means for measuring the sound transmission loss of structures when the sound wave is vertically incident,and there are two kinds of measurement methods,i.e.,methods of three sensors and four sensors.The method of three sensors needs to install the sound absorption material at the end of the standing wave tube that has excellent performance of sound absorption,and it assumes that there are no reflection waves in the transmission tube.The method of four sensors,by adding a microphone in the transmission tube,can eliminate the effect of the once reflection wave at the end of the standing wave tube,and it neglects the effect of multiple reflections in the standing wave tube.Therefore,the methods of three sensors and four sensors both have experimental errors.Aimed at the errors caused by neglecting the multiple reflections inthe method of four sensors,a modifier formula is derived in this thesis by considering the multiple reflections in the standing wave tube.The Matlab program is compiled according to the modifier formula,and the acoustic numerical model is established by the Virtual.Lab Acoustics.According to the computation method of coupled acoustic finite element,the sound transmission loss of panel is simulated with four sensors.By changing the sound absorption coefficient of the standing wave tube,the computation results of the modifier formula are compared with those of the method of three sensors,the method of four sensors without amending and the theoretical value,which has proved the correctness of the modifier formula.In order to explore the factors that affect the experimental results of the method of four sensors,the standing wave tube method is simulated numerically.A finite element model for measuring the sound transmission loss of construction is established.By comparing the simulation results with the experimental results and theoretical solutions,the influences of the Young’s modulus,Poisson’s ratio and density of the standing wave tube materials on the measurement of sound transmission loss are studied respectively.The results show that the most influential factor is the Young’s modulus.When the Young’s modulus is more than 15 times of the Young’s modulus of the sample material to be measured,the measurement results can be trusted;when the Young’s modulus is relatively small,the Poisson’s ratio and density have a certain effect on the results;and when the Young’s modulus is large enough,the influences of Poisson’s ratio and density can be neglected.In order to improve the sound insulation effect of ship cabin,honeycomb sandwich board is more and more widely used.The factors affecting the sound insulation performance of the honeycomb sandwich panels are studied by numerical simulation of the standing wave tube method.Firstly,a finite element model of honeycomb sandwich panels is established.Then the modal analysis method is used to calculate the soundinsulation performance of honeycomb sandwich panels with different material parameters when the sound wave is vertically incident.The results show that the factors such as the panel thickness and density,Young’s modulus and density of honeycomb structure and Young’s modulus of honeycomb will affect the sound insulation performance of sandwich panels.Aimed at the standing wave tube experiment for measuring the sound transmission loss of cabin plate,numerical study is carried out in this thesis by deriving a modifier formula that is used for processing experimental data,and by exploring the effects of material parameters of the standing wave tube on measurement results.Based on the study,reference commends are provided for measuring the sound transmission loss of structures by using standing wave tube.Besides,by using the numerical simulation of standing wave tube method,the influence factors of the sound insulation of the honeycomb sandwich plate are discussed.The research results of this thesis can provide a certain reference for measuring accurately the sound insulation of structures,and are of a certain practical application value.