Damage mapping of GFRP via electrical resistance measurements using nanocomposite epoxy matrix systems

In the present study a technique for damage detection in nanoparticle-modified glass fibre reinforced polymer (GFRP), using in-plane and through-thickness electrical resistance measurements, is presented. Via this technique barely visible impact damages could be detected, localised and characterised (damage mapping). Dispersion of different filler contents of MWCNT and CB was achieved in a three roll mill. GFRP laminates with the modified matrix were manufactured with VARTM. Damage detection is realised measuring the electrical resistance distribution of the specimens before and after impact and the analysis of the damage correlated relative resistance changes. For the measurement a conductive silver ink electrode grid was directly applied to the specimen's surfaces, allowing a reliable localisation of the impact damages through damage mapping. Comparison between ultrasonic C-scans and the electrical damage mapping for a majority of the specimens showed a reliable correlation in the positions of the impact related delaminations. Different nanoparticle modifications of the GFRP-laminates resulted in a significant variation of the sensitivity of the damage mapping method. The found results show a large influence of the orientation of the electrodes as well as the used nanoparticles on the evaluated damage maps. Multiple impact tests showed the suitability of the developed damage mapping-technique for the characterisation of damage propagation regarding interlaminar delaminations and surface near matrix cracks.