A sensitivity analysis on the damage detection capability of a Lamb waves based SHM system for a composite winglet

Lamb waves based Structural Health Monitoring (SHM) systems, thanks to their high sensitivity to damage detection and the ability to travel over a long distance with low power consumption, are founding increasing industrial applications, especially in the aerospace field, where airworthiness authorities require that composite materials in primary structures must remain undamaged during the in-service life. In order to tolerate damage and monitor its severity and, consequently, to repair the structure only when strictly needed, the use of SHM systems appears to be an efficient solution providing benefits for the current design practice. The continuous assessment of the structural integrity, which can be accomplished by SHM systems, can play a key-role to achieve a less-conservative design as well as to facilitate maintenance operations. This paper deals with a sensitivity analysis, based on the Finite Element (FE) theory, aimed to investigate numerically the influence of the damage orientation on the damage detection capability of a Lamb waves based SHM system arranged on a damaged Glass Fiber Reinforced Polymer composite winglet. Damage detection sensitivity has been measured by analyzing the interaction between the modelled damages and guided waves under a specific central frequency. Signals recorded at different locations by piezoelectric sensors have been compared with the baseline signals achieved under a pristine configuration of the winglet by means of a damage index. A specific trend of the considered damage index has been found out as function of the damage orientation.