Acoustic & Imaging

Introduction

Acoustic waves are mechanical vibrations which propagate through a material medium such as solid, liquid and gas. Acoustic waves carry the information of the excitation source and also collect the information on its propagation paths. The applications of acoustic waves cover an impressively wide frequency range of 10^-2-10¹⁰ Hz and a travelling distance of 10^-6-10⁷ m, which enables acoustic waves to be a useful tool for medical imaging, non-destructive evaluation, underwater imaging and communications, and seismological planet study, etc.

Originated as a mechanical response of a medium to a transient perturbation, acoustic waves are capable of interacting with multiphysics mechanisms. The couplings between the acoustic waves with mechanical, optical, thermal, electrical and magnetic phenomena render an exciting and interdisciplinary research area.

The Acoustic & Imaging group focuses on the investigation of the couplings of acoustic waves with multiphysics mechanisms and the development of novel imaging technologies based on multiphysics acoustic interactions. Some of the current research activities in the group as shown in Figure 1 include:

• Wave propagation and wave generation in complex material media. This includes wave propagation in complex material systems and acoustic emission in complex physical and chemical processes.
• The interactions of acoustic waves with micro-/macro-structural defects and acoustic interactions with multiphysics mechanisms.
• New concept of imaging technologies based on multiphysics acoustic-optical interactions.
• Innovative acoustic transducers and optical imaging technologies which enable the investigation of the above works.
  
  

Figure 1. Current focus areas of Acoustic & Imaging group

The acoustic shearography technology is an example of a new imaging technology based on acoustic-optical and acoustic-material interactions. By monitoring the surface optical changes due to wave-defects and wave-optical interactions, both surface and deep subsurface defects in a solid material can be imaged in nearly real-time. This technology has combined advantages of fast and full-filed imaging of optical techniques and deep penetration of acoustic waves, which is suitable for high-efficient defect imaging in aerospace, marine and offshore, manufacturing, built environment and electronic industry.

Capabilities

We have established strong and comprehensive capabilities in the following areas:

1. Acoustic shearography system for defect imaging.
2. Acoustic methods for measurement and evaluation of mechanical properties of complex material media.
3. Acoustic emission and optical imaging methods for capturing and visualizing of transient damage evolution in materials.
4. High-power directed acoustic wave transducers and high-power phased array systems.
5. Design, simulation and fabrication of innovative acoustic transducers with new and improved functionalities.

Achievements

• Pioneered in development of patented acoustic shearography technologies for defect imaging.
• Development of directed acoustic shearography system featuring innovative high-power directed acoustic wave transducers and high-power phased array systems. 

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