The Research On Vibration And Acoustic Characteristics Of Composite Laminated Plate With Hole

As a new material,composite materials have a number of advantages for ship applications for the characteristics of light weight,high specific strength and specific stiffness,fatigue resistance,corrosion resistance and easy processing.In order to meet the requirements of equipment installation,channel increase,weight reduction,etc.,it is usually necessary to open various shapes of openings in marine structures according to the actual needs.The vibration and sound radiation characteristics of the ship are important indicators for evaluating the performance of the ship.Therefore,the vibration and sound radiation characteristics of the composite laminate structure with openings are studied,which has reference significance for the vibration and noise control in practical applications.The research on the free vibration characteristics of composite laminates with different shapes and openings is presented firstly in this study.Based on the first-order shear deformation theory,the vibration of laminated plates is described,and the energy functions are derived.The general boundary is simulated by linear and evenly distributed translational and rotational springs.Based on the Rayleigh Ritz method,the improved Fourier series is used as the assumed mode function to deduce the vibration energy functions that can be applied to plates with different shapes,openings and boundaries.The stiffness and mass matrix of the plate can be obtained by finding the extreme value of the energy functional.By solving the eigenvalue matrix,the natural frequencies and modes of free vibration are obtained.The calculation results of natural frequencies of laminated laminates with different shapes are given,and compared with the finite element results and references,the correctness of the theoretical model and the calculation program in this paper is verified,and the influence of openings parameters on the natural frequencies of laminated laminates is discussed.On the basis of free vibration,the forced vibration and power flow characteristics of the laminate plate with opening were studied secondly.By inverting the matrix,the coefficient matrix of the displacement function is solved,and the forced vibrational displacement and internal force the laminate plate with opening is obtained.The structural vibration power flow is studied whereafter,and the influence of the opening size and the position of the excitation force on the vibration power flow is discussed in detail.Through the visualization method,the transmission path of energy in the laminate plate with opening is studied,and the influence of structural boundary conditions,excitation frequency and excitation position on power flow propagation characteristics is discussed.Finally,the sound radiation characteristics of the open laminates in the air are analyzed.The Rayleigh integral formula is used to obtain the far-field radiated sound pressure expression of the open laminates.The radiated sound powers of the laminate plate with opening is obtained by combining the impedance matrix.The influence of opening size,structure boundary and other factors on sound radiation is discussed in detail.The research provides a theoretical basis for vibration and noise reduction of open laminated plate structure with openings.