A numerical scheme for finding crack shapes from eddy current measurements has been developed based on a startdard iterative inversion approach in which a nonlinear least squares objective function quantifying the overall difference between predictions and measurements is minimized. In this paper, steepest descent and conjugate‐gradient methods for minimizing the objective function are investigated and compared. Cramér‐Rao lower bounds on the crack parameters are derived to quantify the accuracy of the estimated crack shape. Cramér‐Rao bounds are also used to indicate improvements in the design of eddy‐current nondestructive evaluation systems.
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