1D profiling using highly dispersive guided waves

Abstract

Abstract. Corrosion is one of the industries major issues regarding the integrity of assets. Currently inspections are conducted at regular intervals to ensure a sufficient integrity level of these assets. Cost reduction while maintaining a high level of reliability and safety of installations is a major challenge. There are many situations where the actual defect location is not accessible, e.g., a pipe support or a partially buried pipe. In case of bottom of the line corrosion, i.e., a single corrosion pit, a simpler approach may be followed. Guided waves are propagated around the circumference of a pipe. In case of wall loss, the phase of the signal changes which is used to estimate the local wall thickness profile. A special EMAT sensor has been developed, which works in a pit-catch configuration at the 12 o'clock position using highly dispersive guided waves. In order to improve the sensitivity, an inversion in performed on multiple orders of circumferential passes. Experimental results are presented on different pipes containing artificial and real defects.

Least-squares reverse time migration (LSRTM) for damage imaging using Lamb waves

“…As mentioned earlier, a normalized ZLCC imaging condition [15] in RTM can generate the reflectivity or the reflective coefficients of the damaged region. This physical meaning of the image is particularly useful because it can be converted to plate thickness loss or stiffness change through dispersion relations such that damage severity can be quantified as well [52].…”

Guided wave tomography based on least-squares reverse-time migration

“…It clearly depends on the depth or severity of damage. 48,49 Harvesting the non-dispersive characteristic of shear-horizontal (SH) waves, 50,51 Wang and Hirose 52 inverted damage shapes using reflection coefficients of damage-scattered SH waves.…”