The Research Of Vibration Radiation Characteristics Based On Time Domain Analysis For Curve Shell Structures

With the progress of human civilization,especially the rapid development of modern industry,noise pollution problems ensued and will seriously affect the human production,life,work and health.At the same time,the curved shell structure,due to its own excellent physical and geometric properties,is used more and more widely in the aerospace,civil engineering and mechanical engineering and other engineering applications.When the curved shell structure is inspired by the load,it will produce the corresponding vibration radiation noise.It is necessary to study the vibration and radiated noise characteristics of the shell structure.At present,most study of structural vibration radiation noise is based on the frequency domain.However,there are a large number of time-varying transient load sources and sound sources in engineering problems.Therefore,based on the time domain analysis,the sound pressure characteristics of vibrating radiation are studied by combining the structural finite element method and the boundary element method of acoustic field in this paper.First,the finite element model of the curve shell is established.In this paper,the finite element formula of the eight-node space shell is given,and the finite element equation of the single-layer shell structure is formed.Then,by introducing the coordinate transformation,the stiffness matrix and mass matrix of the laminated curve shell structure are deduced.The static analysis and modal analysis of curve structure is analyzed by the aforementioned model.The validity of the finite element model and the program codes is verified,which can be founded as the analysis of vibrating radiation sound pressure characteristics for curve shell structures.Then,the sound field model of time domain is built up.For the transient sound field,we obtain the acoustic boundary integral equation in the time domain by using the delta function and Laplace transform and its inverse transformation based on the three-dimensional wave equation with time parameters.For acoustic boundary integral equation,it is performed to the discretion of equation in time and space domain,and the corresponding numerical calculation model of boundary element is constructed.Taking the typical structural acceleration as the boundary condition of the acoustic field,the relationship between the sound pressure and the acoustic flux of the vibration radiation is discussed.Finally,the sound pressure characteristics of vibrating radiation in the time domain is studied by combining the finite element model of the curve shell structure and acoustic boundary element model.On the basis of the above,the sensitivity formula of sound pressure of vibration radiation is further deduced.Numerical examples show the sensitivity of the sound pressure of the vibration radiation of the curved shell structure with respect to the geometric parameters which include the thickness of the single shell structure,the laying thickness and the laying angle of the laminated shell.And the results of sensitivity analysis have good agreement with the results of the finite difference method,which demonstrates the sensitivity analysis method presented in this paper,based on time domain analysis,has a good precision.