Damage Monitoring of Carbon/Glass Hybrid Composites Under Tensile Load Based on Digital Image Correlation and Acoustic Emission Technology

ABSTRACT Lightweight fiber‐reinforced polymer composites (FRPs) possess performance advantages such as high specific strength, specific modulus, and low thermal expansion coefficient. Nevertheless, the mutual exclusivity between strength and toughness restricts their application to a certain extent. In this research, the damage process of carbon/glass fiber hybrid laminates (C/G) under tensile load was tested by acoustic emission (AE) and digital image correlation (DIC) techniques, and the failure mechanism was investigated by finite element calculation. The experimental results indicated that the increase of central carbon fiber layers exacerbated the brittleness of C/G hybrid laminates. The yield strain and failure strain of C/G hybrid laminates decreased from 2.164% and 2.596% to 1.833% and 2.102%, respectively. Furthermore, through the comparative analysis of AE signals, it was demonstrated that AE technology was capable of detecting the pseudo‐ductile stage of C/G hybrid laminates. High‐amplitude and high‐energy AE signals were concentrated. The cumulative impact count increased by 635,078, accounting for 50.97% of the total, and more than half of the impact events occurred in this stage. The introduction of slits in the carbon fiber layers increased the cumulative impact count and relative energy accumulation in the damage propagation of C/G hybrid laminates.