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

在几乎所有航空航天、铁路和汽车的设计和运行中，内部噪声是一个重要的考虑因素。室内声级主要是由主体结构和附加隔音材料的性能和复杂性控制的。现在常用的是大型复合板和夹心饰边。这种组件重量轻，耐腐蚀，但它们不能提供足够的隔音或减振。为了满足新的进站振动和噪声规定，必须降低高振动水平和客舱噪声。这需要对它们的噪声传播机制进行详细和基本的调查，并设计具体的噪声控制处理。这是拟议研究计划的主要目标。旨在通过建模和测试，识别、理解、量化和优化复合材料和夹层结构的传递和耗散机制，并在此基础上开发新的降噪声学材料。具体目标是：(i)开发和实验验证在各种激励（漫射声场，机械，湍流边界层…）下的夹层和复合复杂结构（肋，弯曲，带装饰支架和声音包的双壁）的全频谱数值模型；（ii）研究嵌入阻尼（粘弹性、毛毡）的蜂窝夹层结构的声学和振动性能；（iii）研究和开发具有更高低频和中频吸收性能的创新型多功能材料；特别是双孔材料、智能泡沫、带有微孔电阻屏的多层材料，以及（iv）设计和测试一种优化的、完全具有代表性的飞机复合材料侧壁，包括隔音包装、夹层饰板和支架（概念验证）。本研究将结合最先进的计算方法（分析方法、有限元素和边界元素方法、统计能量分析、混合方法等）和实验工具来解决这些具有挑战性的问题。后者是为了(i)阐明主要的物理现象，（ii）表征所研究的结构和声学材料，（iii）验证当前和开发的建模工具的预测，以及（iv）展示开发的设计和概念的潜在好处。拟议的研究本质上是一般性的。航空航天、汽车、铁路和建筑等几个行业都对它感兴趣。

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.