Lamb-wave tomography (LWT) offers a powerful nondestructive technique for the health
assessment of large structures as their propagation properties depend on the thickness
and the mechanical properties of the material. Development of a fast and accurate algorithm
for defect detection is of paramount importance in any structural-health-monitoring
(SHM) system. The present study explores the prospects of LWT as a SHM technique with
an accent on developing a suitable algorithm for real-time inspection. Projection data is collected
by electronically scanning an array of ultrasonic sensors arranged in a modified
cross-hole geometry. The data thus collected is investigated to extract energy profile of
the traveling waves. Multiplicative algebraic reconstruction technique (MART) algorithms
are used as a tool for tomographic reconstruction from a set of multiple independent
measurements. The performance of algorithms is evaluated from the point of view of the
cost of algorithm, achievable resolution, and accuracy of results. Experimental results show
that MART is capable of characterizing defects in thin isotropic and composite plates within
a reasonable error band ( 26% normalized, 2.6 RMS) and is suitable for application
to LWT of large structures such as aircraft skins.
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