IEEE Seminar - Ultrasonic Focusing and Imaging in Damage Detection Scenarios

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Dr. Abhijit Ganguli
Assistant Professor
Dept. of Civil Engineering, IIT Delhi

will speak on

"Ultrasonic Focusing and Imaging in Damage Detection Scenarios"

Abstract:
Concepts of ultrasonic imaging with phased arrays related to biomedical engineering are
finding increasing application in non‐destructive evaluation of solid structures.
Ultrasound is typically used in the imaging of the fetus and breast cancer monitoring.
Focused ultrasound is used in ablation of cancer affected tissues. Even though
phased array technology is used in damage detection scenarios, research on focused
ultrasound in non‐destructive evaluation scenarios is still in a developmental stage.
Beam steering and focusing enables the user to interrogate a particular region of
interest inside the material. However, the ultrasonic wave propagates with decreasing
amplitude in an attenuative material, leading to lower energy levels reaching the target.
The first part of my talk deals with evaluation of the efficiency of ultrasonic focusing
in an attenuative medium like cement ortar or concrete (one of the most common materials
in civil engineering solids) through ultrasonic measurements.

The second part of my talk deals with numerical simulations on the Synthetic Aperture
Focusing Technique (SAFT) for the detection of air void defects affecting various locations
inside a reinforced concrete medium. Low frequency elastic wave propagation, generated
by the Impact‐Echo method is simulated in two dimensions, using the Finite Difference in
Time Domain (FDTD) method. Waveforms received at various receiver locations on the surface
are cross‐correlated with a reference point scatterer response function to form an interior
image of the concrete medium. We also demonstrate that by using all of the mode conversions
of the scattered wave in the image synthesis results in a more rbust sensing algorithm.

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Refreshments will be served at 3:45 PM.

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