The fabrication of mechanoluminescent composites manufactured via the displaced foam dispersion technique

Mechanoluminescent (ML) phosphors are ideal components for the structural health monitoring (SHM) of in-service fibre-reinforced composites (FRCs); the integration of ML phosphors however, has proven difficult due to ML phosphor properties such as density, morphology and chemical structure. This paper seeks to address such processing difficulties through the utilisation of the novel displaced foam dispersion (DFD) technique. The displaced foam dispersion (DFD) technique is a particular method for manufacturing particulate composites in which particulates are integrated into expendable PS foams. The foams are then placed between fibre fabrics and dissolved upon the infusion of vinyl ester (VE) resin, leaving the particulates in place. Herein, ML-FRCs using two varieties of ML phosphors are manufactured via the DFD technique followed by short beam shear (SBS) testing. Scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) are used to observe sample cross sections as well as identify the spatial location of ML phosphors and fibre constituents. Short beam shear tests indicate a reduction in shear strength with the integration of polystyrene (PS) foam however, the integration of ML phosphor foams yielded slightly stronger composites as compared to samples with only PS foams. SEM and EDS analysis yield the spatial location of constituents as well noticeable differences in fibre compaction that correlate with reductions in strength. The results of this study reveal important variables for /considerations for further development of the DFD technique for the fabrication of ML-FRCs.