Vibroacoustic modeling and design of sandwich and composite lightweight structures with innovative noise control materials

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Interior noise is an important consideration in the design and operation of virtually all aerospace, railways and automotive vehicles. The interior sound level is primarily controlled by the properties and complexity of the main structure and the attached sound proofing materials. Large composite panels and sandwich trims are now commonly used. Such assemblies are lightweight and resistant, but they do not provide sufficient sound isolation or vibration damping. High vibration levels and cabin noise must be reduced in order to meet with new incoming vibration and noise regulations. This requires a detailed and fundamental investigation of their noise transmission mechanisms and the design of specific Noise control treatments. This is the main objective of the proposed research program. It is aimed at identifying, understanding, quantifying and optimizing through modeling and testing, the transmission and dissipation mechanisms through composite and sandwich structures, and on this basis developing new noise control acoustic materials. The specific objectives are: (i) to develop and experimentally validate full frequency spectrum numerical models for sandwich and composite complex structures (ribbed, curved, double walls with trim mounts and sound packages) under various excitations (diffuse acoustic field, mechanical, Turbulent Boundary Layer...); (ii) to investigate the acoustic and vibration performance of Honeycomb sandwich structures with embedded damping (viscoelastic, felt), (iii) to investigate and develop innovative multifunctional materials with higher absorption performance at low to mid frequencies; in particuler double porosity materials, smart foams, multilayers with microporous resistive screens and (iv) to design and test an optimized fully representative aircraft composite sidewalls with sound package, sandwich trim panel and mounts (proof of concept). The proposed research addresses these challenging issues using a combination of state of the art computational methods (Analytical methods, Finite and Boundary Element Methods, Statistical Energy Analysis, Hybrid methods ...) and experimental tools. The latter are undertaken to (i) elucidate the main physical phenomena, (ii) characetrize the studied structures and acoustc materials, (iii) verify the prediction of the current and developed modeling tools, and (iv) demonstrate the potential benefit of the developed design and concepts. The proposed research is generic in nature. It is of interest to several industries such as aerospace, automotive, railway and building.