Emiliano Rustighi

The law of reciprocity in acoustics and elastodynamics codifies relations of symmetry between the signals emitted by sources and detected by receivers in fluids and solids. In its simplest form, it states that the frequency response functions between any two material points remain the same after swapping the roles of source and receiver. As such, reciprocity has enabled numerous applications in the field of acoustic and elastic wave propagation.  Recent changes in this paradigm have prompted the realization of nonreciprocal wave-bearing media which may enable the creation of devices such as acoustic one-way mirrors, isolators, and topological insulators.

The main challenge of this project is to design and realise a continuum-based metamaterial whose properties can be tuned in both space and time at the length and time scales of the guided waves. Such mechatronic metamaterial could be realised repeating a unit cell with a locally resonant structure realised by a permanent magnet which oscillates between two coils. The current supplied to the coil can be used to change the effective stiffness of the oscillator. A feedback loop can be also used to tune the metamaterial properties according to a desired objective. The student will have to build and analyse simplified analytical and numerical models of the mechatronic metamaterial. Some experimental work will be carried out to support the numerical results.

Leakage from pipes is a major issue in the water industry, causing economic, health, and environmental concerns. Acoustic methods are commonly used for leak detection, but their effectiveness is limited for modern plastic pipes due to high wave attenuation. This project aims to develop a numerical simulation using Finite Element Method (FEM) to study the propagation of pressure oscillations in a fluid contained inside a buried pipe and their transmission to the pipe wall and surrounding soil. The simulation will involve the coupling of three different systems: the fluid as an acoustic medium, the pipe, and the soil as linear elastic structural mediums. The study will investigate the coupling between fluid-pipe-soil and provide insights into the dynamic behavior of buried piping systems.

The project will focus on the development of time domain explicit analysis FEM models of a water-filled buried pipe to study the noise transmission from a leak to the ground surface and validate existing analytical models. The study will contribute to the development of efficient and robust designs of leak localization techniques and provide valuable insights for the water industry. The project would suit a candidate with strong analytical/numerical skills and an interest in acoustic and vibration analysis.

Structural vibration can be described using a modal or a wave approach depending on the application. Wave approaches are more appropriate at high frequency where a high modal overlap is present. However, experimentally the structural modal behaviour can be easily obtained from the point measurements of displacements or accelerations. The aim of this project is to design a wave-field sensor that uses the signals from an array of accelerometers to obtain travelling wave estimations. A lab version of this sensor has been previously implemented but it was limited to beam and dependant on the previous knowledge of the wavenumber of the structure. During the project the student will have to initially model wave propagation in beams and plates. Subsequently the next objective of the project is to implement the wave filed sensor in an infinite beam using an Arduino or Bela board. The use without the knowledge of the wavenumber will be investigated. Next the device will be modified to be used on flat plates.