Imaging of 3D elastic waveguides – Application to rails

The objective of this PhD research is to develop and optimize innovative imaging methods adapted to 3D elastic waveguides, with a specific application to rails. These methods must account for instrumentation constraints (limited number of transducers) and the particular characteristics of guided waves (dispersion, multimodality). Based on the mathematical framework of inverse problems in elastodynamics, the proposed approach will rely on evaluating a gradient that reveals the sensitivity of a cost function to the medium’s parameters. This approach, based on the adjoint state and the modal formalism of waveguides, will enable rapid defect localization (imaging) without requiring iterative computations.

Already applied to 2D elastic waveguides (plates), this methodology will need to be extended to 3D waveguides (rails), raising several questions about:
– the influence of measurement and excitation configurations (frequencies, sensor positions and numbers…)
– sensitivity to uncertainties under realistic conditions (noise, sources…)
– the selection of an appropriate gradient (imaging function) depending on the nature of the defects being investigated.

The PhD candidate will exploit UGE’s modeling tools to:
– develop digital twins to simulate elastic wave propagation in rails, with and without defects, to
– implement and test various imaging algorithms, using synthetic data,
– validate the results using laboratory experimental measurements.

More information on the link below.