Surfactant-modified multiscale composites for improved tensile fatigue and impact damage sensing

Impact damage sensing of multiscale composites through epoxy matrix containing carbon nanotubes

“…Impact damage detection by electrical resistance changes has also been investigated, although more work is needed: among the few available results, Yesil et al 5 showed counter-intuitive results by two-point probe method (being investigated in this present work), Monti et al 14 used low impact energy and two-point probe method, and Gao et al 15 obtained a conductive matrix by adding a sizing agent containing CNTs, which by itself could affect results. Impact damage detection by electrical resistance changes has also been investigated, although more work is needed: among the few available results, Yesil et al 5 showed counter-intuitive results by two-point probe method (being investigated in this present work), Monti et al 14 used low impact energy and two-point probe method, and Gao et al 15 obtained a conductive matrix by adding a sizing agent containing CNTs, which by itself could affect results.…”

“…5 In that work and in the current article, an amount of 0.5 wt % was utilized, for comparison with other studies in the literature. Epoxy matrix containing 0.5 wt % of as-received MWCNTs was prepared for this study.…”

“…Detection of damage through resistance changes requires in principle relatively simple measurements, with electrodes that can be attached in situ with minimal disruption of the surface, and with no major consequence on mechanical properties. 4,5 However, there are surface treatments of CNTs that, depending on their concentrations in resin, cause lower or no conductivity of the resulting polymer when compared with untreated CNTcomposites. Because most polymer matrix materials are good insulators, this requires the incorporation of conductive nanoparticles.…”

“…In addition, the literature reports that epoxy matrices containing up to 0.5 wt % of treated or non-treated CNTs are a percolated conductive network, 5,[8][9][10][11] and this allows damage detection by resistance changes. However, most of the work done seems to rely on a two-point probe measurement, a method that does not take into account contact resistance.…”

“…5, and investigate the efficiency of electrical conductivity-based methods, to detect impact damage in conductive GFRP laminates. 5, and investigate the efficiency of electrical conductivity-based methods, to detect impact damage in conductive GFRP laminates.…”