Damage monitoring of GFRP laminates via electrical measurements: Experiments and predictions

In this work, an experimental investigation is presented on the early-stage fatigue damage of conductive glass/epoxy cross-ply laminates. The study is specifically designed to generate a comprehensive and consistent experimental dataset suitable for the validation of an analytical model previously developed by the authors. Fatigue tests were performed under controlled loading conditions, while transverse matrix cracking in the 90° plies was continuously monitored together with stiffness degradation and changes in electrical resistance. These measurements provide a detailed dataset that enables correlation between mechanical damage and electrical response. The data were then used to validate the analytical model developed by the authors, which predicts stiffness degradation as a function of the resistance change induced by transverse cracking. The good agreement between model predictions and experimental observations confirms the suitability of the adopted experimental approach and supports the use of electrical resistance measurements as a quantitative tool for model-based assessment of early-stage damage in conductive GFRP laminates.