Characterization of triboluminescent enhanced discontinuous glass-fiber composite beams for micro-damage detection and fracture assessment

This work reports the micro-emissions of triboluminescent (TL) concentrated composites and their evaluation at the onset of damage and crack propagation. Unreinforced vinyl ester resin and discontinuous glass-fiber reinforced non-prismatic beams were fabricated incorporating 10 wt% concentration of a highly triboluminescent material (ZnS:Mn). Triboluminescent observations were seen in both two- and three-phase composite systems throughout the failure loading-cycle. Results indicate emissions occur at various intensities corresponding to initial notch-length and imminent micro-matrix fracture. The fracturing or deformation energy was estimated by an experimental method of the J-integral analysis [1], where a lower threshold for excitation was found to be approximately less than 0.5 J m−2, below its respective critical composite fracture energy (~3 and 7 J m−2). Initiation of micro-cracks was observed for reinforced samples and were subjected to three-point bend tests in lieu of the multiple signatures of the transient signal response.