Evaluation of plasticity driven material damage using Lamb waves

This letter reports on the experimental observation of a direct correlation between the acoustic nonlinearity measured with Lamb waves and the level of plasticity in a metal specimen. This correlation implies that even though Lamb waves are multimodal and dispersive, they will interact with a material's plasticity in a manner similar to longitudinal and Rayleigh waves; there is a fundamental relationship between material plasticity and acoustic nonlinearity that is independent of wave type. As a result, Lamb waves can be used to quantitatively assess plasticity driven material damage using established higher harmonic generation techniques.