PhD Actively controlled acoustic shielding

Within the research area Acoustics and noise control the project “Acoustic Shielding” will be started, funded by STW. The goal of this project is the design of advanced cover systems for acoustic shielding of high-tech systems. This project addresses the design of advanced cover systems to shield (parts of) high-tech systems such as MRI scanner, wafersteppers and electron microscopes. This project focuses on novel techniques for combined active-passive covers for high-tech applications, offering efficient acoustic shielding at mid and low frequencies. A breakthrough hybrid passive-active control approach is proposed for the advanced cover systems. For the mid frequency range (from 250 - 500 Hz) a passive approach for noise reduction based on multilayered porous covers will be combined with actively controlled actuators that counteract the noise in the low frequency range (below 250 Hz). Within the project two PhD’s and a postdoc will be working together on the development of passively and actively based acoustic shielding. For the active shielding part, design methods based on physical modelling including the dynamics of the cover support system must be developed to implement an active control system that improves the acoustic shielding in the low frequency range (below 250 Hz). One of the focus points is to derive a cost criterion which is appropriate for the application at hand. Also for the active part an optimization of the multilayered actively controlled cover panels will be performed.

The main scientific challenge lies in the development of appropriate control strategies and the definition of a descriptive cost function to achieve an effective shielding of acoustic noise at low frequencies.
The tasks involve the definition of the cost criterion, taking into account the specific acoustic properties of the application involved (wafer-stepper, MRI scanner) and taking into account the structural dynamics of the cover system supporting structure as well. A refined poro-elastic model as developed by the companion PhD, will be incorporated in the theoretical work as well. This combined structural-dynamics poro-elastic model will be used to optimize sensor and actuator type and position and controller to achieve optimal control. In cooperation with a post-doc the control system will be implemented on a dedicated test-rig and validation measurements will be carried out. The research will be conducted in cooperation with the group of Mechanics of Materials (TU/e) and a group of companies – producers of high-tech systems like wafer steppers and MRI-scanners.