Guided-Waves in a Low Velocity Impacted Composite Winglet

Airworthiness authorities require that composite materials in primary structures must be undamaged all in-service life long, resulting in an oversizing of structural components and in a general increasing of weight. To allow structures working in presence of damages but showing an acceptable residual strength, in recent years a significant interest has been pointed out in the capability of ultrasonic guided waves as candidate tool for Structural Health Monitoring (SHM) of composites. The continuous assessment of the structural integrity, that can be accomplished by means of SHM systems, would provide, in fact, a less-conservative design and significant benefits in repair operations. In this work, a description of two numerical techniques based on Finite Element Method (FEM) for the simulation of Lamb wave propagation in a damaged Glass Fibre Reinforced Polymer composite winglet is presented. The interaction between damage and guided-waves has been investigated under two central frequencies: 100 kHz and 150 kHz. Root Mean Square Deviation Damage Index has been used to compare the baseline signals (achieved under the pristine configuration) and the respective signals achieved under the impacted/damaged one. Numerical models have been assessed against an experimental tests campaign.