Electrified fracture of nanotube films

Strong and conductive carbon nanotube films are ideal candidates for lightning-strike protection. Understanding their failure mechanisms by considering the anisotropic and single-fiber nature is essential to improve the performance. Our experimental studies show that the single-layer, nanometer-thick films fail under electrification by crack nucleation and propagation, reminiscent of brittle and ductile fracture of materials under mechanical loads. Sharp and diffuse patterns of fracture are identified in aligned and nonwoven films, respectively, signaling the strong effect of material anisotropy that is absent in common engineering materials. The fracture is driven by local Joule heating concentrated at the crack fronts instead of force-induced breakage, which is validated by experimental characterization and simulation results at both continuum and atomistic levels.