Harnessing triboluminescence for structural health monitoring of composite structures

Triboluminescent (TL) materials (ZnS: Mn phosphors) were embedded in composite matrices to utilize their inherent luminescent properties for potential structural health monitoring capabilities. Incorporation of Triboluminescent materials into composites raised many important problems involving interactions between dispersion of these particulate crystals and their effects in composite matrices. A rotational mold apparatus was developed to improve dispersion, along with a methodology involving scanning electron microscopy (SEM) techniques to quantify dispersion quality. As design and functionality requirements of engineering structures become more complex; structural health monitoring (SHM) and damage assessment is becoming more rigorous. Though structures involved have regular costly inspections, the fatigue damage associated with composites in SHM systems can lead to catastrophic and expensive failures. Industry and research have no single technique used on its own to provide reliable real-time and cost effective results. This work examines the use of TL crystals embedded in the composite matrices. These crystals react to straining or fracture by emitting light of varied luminous intensity, giving an indication of crack initiation well ahead of catastrophic failure(s). Initial testing has shown that light can propagate through doped resins alone, as well as doped fiber reinforced plastics (FRP) laminates