Sound and vibration in underwater and other structures

该项目旨在提供对水下应用和飞机设计中常见的工程结构的振动和声辐射特性的更全面的了解。这种主体通常由薄的柔性板（包括船体或机身）组成，其通过舱壁或肋或其他空间不均匀性来加强。弹性波沿着或穿过这种结构的传播是非常复杂的，因为肋的作用是将波散射成其他振动模式，周围流体的存在也提供了另一种传播路径和耦合机制来产生声波。在这个项目中，学生将采用一系列先进的渐近和建模技术来更好地理解这一领域的一些关键问题，例如如何最小化来自内部振动源的声音辐射以及如何减少来自周围流体撞击到车辆本身上的噪声。为了取得进展，应通过分析和计算方法来检查各种简化模型，这些方法利用自然发现的长度尺度的差异（建立在[1]中讨论的工作基础上）。如果时间允许，学生还将考虑涂层和其他先进的“智能”材料对声音发射和吸收的影响。[1]P.A. Cotterill，W. J.帕内尔，I. D.亚伯拉罕河米勒和M.索普约束层的时谐反平面弹性响应。声音与振动杂志。348：167-184，2015.

This project aims to provide a fuller understanding of the vibrational and acoustic-radiation properties of engineering structures that are common in underwater applications and in aircraft design. Such bodies are typically composed of thin flexible plates (comprising the hull or fuselage), which are reinforced by bulkheads or ribs or other spatial inhomogeneities. The transmission of elastic waves along or through such structures is highly complex as the ribs act to scatter the waves into other vibrational modes, and the presence of the surrounding fluid also provides an alternate propagation route and coupling mechanism to generate acoustic waves.In this project the student will employ a range of advanced asymptotic and modelling techniques to understand better a number of key questions in this area, such as how to minimize the sound radiation from internal vibrational sources and how to reduce noise from the surrounding fluid impinging onto the vehicle itself. To make progress, a variety of simplified models shall be examined by analytical and computational methods, which exploit the disparity of lengthscales found naturally (building on the work discussed in [1]). The student will, as time allow, also consider the effects of coatings and other advanced 'smart' materials on sound emission and absorption.[1] P.A. Cotterill, W.J. Parnell, I.D. Abrahams, R. Miller, and M. Thorpe. The time-harmonic antiplane elastic response of a constrained layer. Journal of Sound and Vibration. 348: 167-184, 2015.