Analysis Of Vibration And Acoustic Characteristics Of Open Composite Spherical Shells

Composite spherical shell structures are widely used in aviation,aerospace,transportation and other fields.In practical engineering applications,due to the excitation of the external environment,the spherical shell structure will produce vibration and structural fatigue.Moreover,the vibration of the spherical shell will produce radiation noise,which will not only have a negative impact on the spherical shell structure,but also affect the user’s comfort.Therefore,it is of great significance to analyze the vibration characteristics,sound radiation characteristics and sound insulation performance of composite spherical shells for solving the vibration and noise reduction problems of related engineering structures.In this paper,the vibration and acoustic characteristics of open composite spherical shells are studied as follows:1.Based on the classical shell theory,the natural frequency solving equation and response solving equation of isotropic open spherical shells under harmonic excitation are derived.Piecewise Bezier function is introduced to simplify the setting of boundary conditions.The correctness and applicability of the method in this paper are verified by comparison with literature and finite element calculation results.On this basis,the influence of boundary conditions,structural parameters,damping coefficient and other factors on the natural frequency and displacement response of the spherical shell is calculated and analyzed.The relationship between the normal displacement response of different positions on the spherical shell and the external load frequency is analyzed.2.Considering the shear deformation of spherical shells and based on the first-order shear deformation theory,the method in this paper is extended to composite functionally graded materials and laminated structures.Two kinds of composite spherical shell structures(functionally gradient material and laminated material)were studied.The influences of material parameters and shear correction coefficient on the natural frequency and the forced vibration displacement response of the spherical shell under point and surface loads are emphatically analyzed.3.Taking the open composite spherical shell structure as the research object,combining with the spherical sound cavity,the acoustic vibration coupling system analysis model of composite spherical shell is established.The expressions of plane incident acoustic wave,scattering acoustic wave and radiated acoustic wave on the spherical shell are derived.Based on the energy method,the acoustic vibration characteristics of the spherical shell under the action of plane acoustic wave are solved.The relations between the displacement response under different acoustic excitation and the parameters of composite spherical shells is analyzed.4.The radiated acoustic field and radiated acoustic power of composite spherical shell are calculated.The relationship between radiation sound field,sound insulation performance,excitation frequency,material parameters and structural parameters of spherical shells are analyzed.A graphical user interface is designed to solve the vibration characteristics of spherical shells.On this interface,the natural frequencies of spherical shells made of isotropic materials,functionally graded materials and laminated materials and their displacement responses under specific harmonic excitation can be solved simply and quickly.