On Performance Limits In Estimating Thickness of a Plate-Like Structure from a Full-Field Single-Tone Response Lamb Wave Measurement

Abstract

A challenge in wavenumber analysis in steady-state wave fields, specifically in damage detection, lies in identifying the theoretical sensitivity of the system. A tradeoff exists between frequency/wavenumber resolution and the estimated thickness resolution. The current work presents the results of a calculation of the Cramer-Rao Lower Bound (CRLB) for a 1-D multi-mode waveform in Gaussian noise, using the Fisher Information matrix. We conclude by presenting CRLB values against frequency for varying thicknesses. The CRLB values allow for the determination of one or more ideal experimental excitation frequencies given a nominal thickness.