Identification of current material state in composites using a dielectric state variable

Abstract

Damage development in composites is a complicated process, unlike metals where the failure is triggered by unstable growth of a single crack; failure in composites is triggered by interaction of multiple local damage events. The ‘beginning of the end’ in composites is well described in terms of ‘criticality’ and, identification of material state is an important step for predicting this criticality. Current non-destructive evaluation techniques can accurately map the damage zone but are incapable of identifying the material state. In the current research, the main intention is to observe and model the variation in dielectric response as a function of defect development and coupling to characterize the current material state (Characteristic Damage State (CDS), damage interaction) in unidirectional, woven glass fiber reinforced polymer composites loaded in quasi-static axial tension. The changes in dielectric response are correlated with change in material state validated by damage patterns obtained using edge replication techniques.