Thermal sensitivity of Lamb waves for structural health monitoring applications

One of the drawbacks of the current Lamb wave structural health monitoring methods are the false positives due to changing environmental conditions such as temperature. To create an environmental insensitive damage detection scheme, the physics of thermal effects on Lamb waves must be understood. Dispersion and thermal sensitivity curves for an isotropic plate with thermal stress and thermally varying elastic modulus are presented. The thermal sensitivity of dispersion curves is analytically developed and validated by experimental measurements. The group velocity thermal sensitivity highlights temperature insensitive features at two critical frequencies. The thermal sensitivity gives us insight to how temperature affects Lamb wave speeds in different frequency ranges and will help those developing structural health monitoring algorithms.

► Derive Lamb wave speeds with thermal stress and thermally varying elastic property.
► Develop thermal sensitivity of Lamb wave dispersion curves.
► Show critical points on group velocity are insensitive to temperature changes.
► Use thermal sensitivity to predict dispersion curves at other temperatures.