Numerical simulation of guided waves propagation in loaded composite structures

It is well known that Lamb waves based Structural Health Monitoring (SHM) systems have been founding increasing application for damage tolerant composite structures, thanks to the high sensitivity they offer in terms of damage detection, improvement of the design current practice and reduction of the maintenance and inspection costs. However, further investigations are still mandatory for the application of SHM systems on composite structures. Dispersion and slowness phenomena, together with boundary condition scattered waves may mask the presence of damages. In addition, the in-service loads may alter the guided waves propagation mechanisms, affecting negatively the sensitivity to damage detection of such systems. As a result, the development of numerical models aimed to simulate the propagation of guided waves may be helpful for designers to reduce such critical aspects, by allowing virtually investigating different sensors location and different SHM system operating parameters. The novelty of this paper can be found in the development of a Finite Element (FE) model for the simulation of ultrasonic guided waves in a pre-loaded composite structure. Results are herein discussed and the effects of the initial stress-strain state on the guided waves analysed.