Structural health monitoring for GFRP composite by the piezoresistive response in the tufted reinforcements

Abstract

The present paper investigates the damage monitoring using the piezoresistive effect on the glass fiber-reinforced polymer (GFRP) omega stringers reinforced through-the-thickness by tufting. The experiments consisted of the electric resistance measurements from the tufted yarns during the pull-off tests on omega stringers. Acoustic emission (AE) and digital image correlation (DIC) techniques were also performed throughout the tests in order to evaluate the acoustic activity and the strain field respectively. Furthermore, non-supervised AE clustering was carried out and aided to determine the main damage events. The results presented that electric resistance measurements are in good correlation with the AE clusters, especially with those related to the delamination and tuft yarns fracture. Besides, these damage events are well distinguished from the electric resistance data. Also, DIC images exhibited that electric resistance is sensitive to local strain field as expected to piezoresistivity measurements. Therefore, tufting reinforcements have shown to be an interesting monitor of the structural health in real time, further their well-known ability to increase the mechanical out-of-plane properties of laminate composites.