Acoustic & Vibration Characteristic And Radiation Acoustic Minimization Optimal Analysis Of Laminated Plates

Composite laminated plates are widely used in aerospace, shipbuilding, automobile manufacturing and other fields because of its high specific strength, high specific modulus, good fatigue resistance performance, designability and low noise characteristics. In practice composite laminates inevitably excited by external force will produce vibration and radiate sound, which made loud noise. The laminates structure vibration is generally in low frequencies, and the acoustic radiation characteristic depends on structural parameters,excitation location and excitation frequency. Therefore,the study of acoustic & vibration characteristics of laminates structure in low-frequency is of great significance and valuable. This paper will carry out research about the vibration and acoustic radiation performance of laminates structure.Firstly, the vibration characteristics of composite laminates were studied. In this paper, a layerwise theory with finite element method was used to calculate natural frequency, structure modal and dynamic response of the external excitation of the composite laminated plates. The simulation results calculated with the layerwise theory have been verified by comparing with exact solution in the references.Secondly, the acoustic radiation amplitude and acoustic power of laminated plates were calculated based on layerwise theory. And acoustic radiation characteristics of laminated plates with single-point and double-point exciting force were studied separately. It was analyzed that the effects of the number of acoustic radiation modals,the fiber orientation angles, the exciting force location and frequency on acoustic radiation amplitude and acoustic power of the laminated composite plates. The results showed that the factors have different effects on the degree of sound and vibration characteristics of laminated plates.Finally, to optimize the analysis of acoustic radiation of the laminates based on Genetic Algorithm to make it minimized. Theoretically, calculating the acoustic radiation mode amplitude required the entire vibration velocity information on the plate surface, but it is difficult to achieve in practical and few meaningful. Due to the presence of radiation modes orthogonality, this paper put forward that measuring some points’ velocity to obtain the first N-order acoustic radiation mode amplitude’s approximation with the least squares method, and thus minimized the acoustic radiationanalysis. The location of limited points can be optimized based on Genetic Algorithm,which can control the acoustic radiation to become minimum.