M2 internship – Nonlinear Coda Wave Interferometry with active and passive pumps

Keywords: monitoring, diffuse ultrasonic wave, ambient noise

This internship is part of the Horizon Europe Project “USES of novel UltraSonic and Seismic Embedded Sensors for the non-destructive evaluation and structural health monitoring of infrastructure and human-built objects” (USES²) which is granted for 4 years starting March 1 st  2023. The aims of USES², a MARIE SKŁODOWSKA-CURIE ACTIONS Doctoral Network, is to train a new generation of European scientists with skills across sensing and signal processing to develop and combine novel emerging sensing technologies (optical fibre and wireless pieozoelectric sensors), advanced processing (compressed sensing, artificial intelligence) and full-mechanical-waveform-based imaging.
This Master’s internship is part of the Work-Package dedicated to advanced imaging using mechanical waves and focuses on coda waves and non-linear acoustics. The physical idea behind Non-linear Coda Wave Interferometry (NCWI) is to activate, non destructively, the lips of cracks, with a mechanical pump wave (clapping, sliding) and to detect this activation with coda waves. This highly sensitive method is very promising for embedded sensors, providing added robustness for long-term monitoring.

The main aim of the Master’s internship is the design and study of a new methodology that takes advantages of ambient noise as pump source. The work includes several phases combining experimentations, signal processing and numerical modelling:
– Get familiar to the physics of NCWI and to its signal processing methodology
– Define at a macro scale the characteristics of ambient noise compatible with the activation of crack lips
– Map thanks to numerical/analytical modelling the energy of the pump wave
– Perform in the laboratory a classical NCWI experiment on a cracked sample and design an experiment with artificially created noise on the same sample
– Compare the results
– Design and perform an experiment on an in situ structure subject to ambient noise (traffic noise at Cheviré Bridge, Nantes, France)
– Draw conclusion and prospect on the use of ambient noise as a pump in NCWI

Application: Candidates are invited to contact Pierric Mora (pierric.mora(a)univ-eiffel.fr) & Odile Abraham (odile.abraham(a)univ-eiffel.fr). Continuation in a PhD thesis is possible (USES 2 project founding).