Design Optimization Of Curved Shell Structure Considering Acoustic Radiation Characteristics In Time Domain

As one of environmental pollution problems,noise pollution seriously affects people's physical and mental health,and causes troubles to people's production and life.Curved shell structures are widely used in engineering fields such as architecture,and machinery due to their good spatial transmission performance.However,as the thickness of curved shell structure is much smaller than other sizes,this type of structure is easy to produce vibration under the excitation of external load.Therefore,the research on vibration noise and optimization of vibration and noise suppression is of practical significance.At present,most researches on vibration acoustic radiation of curved shell structures are conducted based on frequency domain method.In this paper,the time-domain analysis method,combined with the finite element and boundary element theory,is employed to analyze and study vibration radiation characteristics of curved shell structures in the transient sound field,and the corresponding optimization design of vibration and noise suppression is performed.The main contents are summarized as follows:1.The finite element model of the curved shell structure is established and the application of boundary element method in the time domain analysis of acoustic field is explored.Firstly,a 8-node curved shell element is established,interpolation functions of the 8-node element is given,and then the mass matrix and stiffness matrix of the element model are formulated.By combining the boundary element theory with the classical acoustic theory,the boundary integral equation of the sound field is solved.2.Time domain analysis and optimization design of acoustic radiation response of a single-layer curved shell.On the basis of theoretical analysis,the finite element model of the curved shell structure is established by using finite element software.Based on the finite element model,the structural dynamic analysis is conducted,and the surface response parameters of the structure are obtained.Then,the acoustic boundary element analysis in the time domain is further conducted by using the surface response parameters as the boundary conditions,and the response parameters of the sound radiation are determined.After that,the sensitivity of radiation acoustic pressure with respect to the thickness of the single layer curved shell is performed.On the basis of the sensitivity analysis,the optimization formulation is given,where the structure thickness is selected as the design variables,the space of radiation sound field sites sound pressure is set as the objective function,and the structure weight is the constraint condition.The method of moving asymptotes is used to solve the optimization problem,and numerical examples show that the optimized radiation pressure decreases obviously.3.Time domain analysis and optimization design of acoustic radiation response of laminated curved shells.Based on the single-layer curved shell structure,the coordinate transformation and the integral of the thickness direction are performed to derive the finite element equation of the laminated curved shell structure,and the dynamic and acoustic response analysis of the laminated curved shell structure are conducted.The sensitivity analysis of sound pressure with respect to the thickness of laminated curved shell is carried out.Then,the optimal design of the laminated curved structure is performed by taking the thickness of the symmetric laminate as the design variable,the sound pressure on the surface of the structure as the objective function,the weight as the constraint condition.The optimized structural design parameters are obtained,and the optimized amplitude of the sound pressure decreases obviously.