The Research On Sound Insulation And Noise Reduction Based On Slab With Periodic Gaussian Surfaces

Based on the research and basic theory of periodic composite structure, thecharacteristics of band gaps and the performance of sound insulation and noisereduction of periodic composite structure slab with periodic Gaussian surfaces arestudied, and the feasibility for noise and vibration control in engineering structures ispresented. Besides, we have optimized the low-frequency band gap of the plate withperiodic Gaussian surfaces and the plate with periodic stubs to find the best systemthat could insulate the noise and control efficiently and effectively. The main work isshown as following:The Lamb wave band structure of one-dimensional thin plate with periodicGaussian surfaces is calculated with the eigen-mode matching theory (EMMT)method. The finite element method (FEM) is also employed to calculate thetransmission power spectra (TPS) and the band structure, which are both in goodagreement with the results of the EMMT method. In contrast with the straight stubs,the low-frequency band gap of the system with the Gaussian surfaces is wider, whenthe Gaussian domain’s height and area are equal to those of the stub, and two systems’main plate size and materials are the same. This can be confirmed by the“spring-mass” model, which could be used to estimate the resonant frequency.Because the band gaps are sensitive to three geometrical parameters, w e alsoinvestigate the effects of these geometrical parameters on band structure, includingthe height of the Gaussian domain, the plate thickness and the filling fraction. Theresults suggest that the band gaps have a close relevance to them. By this way, wehope to find a plate with periodic Gaussian surfaces with proper geometricalparameters to meet specific requirements in practice.In addition, to optimize the width of the lowest band gap, radial basis functionand genetic algorithm are employed to achieve the widest lowest band gap to bettercontrol the noise. The optimal value of the plate with periodic Gaussian surfaces is0.1523MHz, while the true value of the plate is0.1501MHz. The optimal value of theplate with periodic stubs is0.1604MHz, while the true value of it is0.1553MHz. Theerrors with both true values are less than5%, which indicate that the results areaccurate and it’s appropriate to utilize radial basis function and genetic algorithm tooptimize the width of forbidden band gaps.