| Composite plates with multifunctional microporous viscoelastic layers(MMVL-CP)possess a series of advantages such as light weight,strong vibration and noise reduction ability,outstanding radar wave absorption,good fatigue and wear resistance and relatively low cost.Such kind of material can play a key role in the comprehensive control of structural noise and vibration as well as electromagnetic stealth.Therefore,the research on the modeling of vibration,noise,and wave absorption characteristics of MMVL-CP is of great significance in academic and engineering areas.This paper takes MMVL-CP structures as research object,and establishes analytical models to predict the vibration,noise,and wave absorption characteristics of this type of structure.The effectiveness and accuracy of the theoretical model are verified by experimental results.The main content of this paper is listed as follows:(1)Fiber-metal hybrid laminate with microporous viscoelastic layers is taken as the research object.The expressions of equivalent elastic moduli of viscoelastic materials with twodimensional regularly distributed micropores is derived.The classical laminate theory is adopted to describe the displacement field of the metal layers and fiber layers,and Reddy’s higher-order shear deformation theory is used to express the displacement field of the microporous viscoelastic layer.The natural frequencies,damping ratios and vibration response are solved based on the Rayleigh-Ritz method,the strain energy method and the mode superposition method.Moreover,the experiment is carried out to verify the proposed model.Besides,the influences of the geometric parameters of micropores on the vibration characteristics are discussed.(2)The fiber-reinforced composite sandwich plate with a microporous viscoelastic core is taken as the research object.The displacement field is expressed based on the first order shear deformation theory,and the Fourier series is selected as the displacement test function.The elastic boundary is simulated by introducing virtual springs.The vibration response of the MMVL-CP structure is solved by utilizing the Ritz method.Considering the influences of plane sound wave excitation,the sound pressure response is obtained through the Rayleigh integration.Furthermore,the sound power level and sound transmission loss are solved to evaluate the sound radiation characteristics and sound insulation effects of the MMVL-CP structure.In addition,using the self-designed vibro-acoustic characteristic test system,the integrated vibration and acoustic characteristics tests research is performed to validate the proposed model.Moreover,the influences of boundary conditions and distribution patterns of micropores in the viscoelastic core on the vibro-acoustic characteristics are discussed based on the verified model.(3)Another fiber-reinforced composite sandwich plate with microporous viscoelastic core layer as research object to study the radar wave absorption characteristics of such kind of material.The reflectivity of such structure is derived through the transmission line method.The correctness of the proposed theoretical model is verified by comparison with literature results and experimental results.Furthermore,the parametric analysis is carried out concerning the influences of the thickness of the core and the mass fraction of the carbonyl iron powder in the core on the radar wave absorption performance of the MMVL-CP structures.The results of this paper can provide a foundation for the analysis of the vibration,noise,and wave absorption characteristics of the MMVL-CP structure.The proposed analytical model proves to be effective in predicting the dynamic response of MMVL-CP structures under structural and sound wave loads,as well as the absorption and reflection characteristics of radar waves in common frequency bands.The research can provide theoretical and practical references for the application of such type of material in aeronautical and other fields. |
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