Mathematical modeling of Lamb wave scattering for structural health monitoring

Abstract

The ability to estimate and suppress part of the reflected energy from the structural boundaries in the received signal to obtain the reflections solely due to damage is explored. When the ultrasound transducer transmits a pulse into the structure to be interrogated, a reflected wave from the structural boundaries and/or damage is detected by the ultrasound receiver. In typical Lamb wave simulation practices, with a view to simplify the wave signal interpretations, effects of structural boundary reflections are often not considered. Although such Lamb wave simulation practices are effective in case of infinite plates, the same method is inapplicable in case of finite plates, because the effect of structural boundaries causes intricacies especially for transient response simulations. In this paper, a specific statistical method is used to model the reflections from structural boundaries. Indeed, this modeling is efficient in case of finite plates. Such a modeling can also be used to examine and suppress part of the reflected energy from the structural boundaries in received signal to procure the signal containing the reflections only due to damage. The proposed algorithm has been evaluated in both simulation and experimental tests on an 6061 aluminum plate with dimensions 300 mm × 300 mm × 3 mm. The tests yield considerable improvement in the accuracy of estimating the position of the flaw.