In-situ Damage Precursor Detection in Fiber Reinforced Composites Using Mechanochemical Materials

摘要

Optical responses of mechanophore (stress-responsive materials) in fiberreinforced polymer composites under mechanical loads were characterized. A newexperimental system was developed to capture in situ mechanophore activation byrecording ultraviolet (UV) excited fluorescence during uniaxial load tests. Anthracene-based mechanophore, dimeric 9-anthracene carboxylic acid (Di-AC) was synthesizedand incorporated into an epoxy-based thermoset successfully. This Di-AC embeddedepoxy mixture was applied to glass fiber fabric to fabricate mechanophore embeddedglass fiber reinforced polymer (GFRP) composites through hand-layup process.Quasistatic and cyclic loads were performed to investigate the effect of different typesof loads on mechanophore activation. The results indicated that mechanophoreactivation occurred at the beginning of the test during the quasistatic loading test andcontinued linearly before yield. Microcracks were formed in the matrix prior to yield,and UV intensity of the mechanophore exhibited nonlinear response. During fatiguetests, the intensity of fluorescence increased after a certain number of cycles.Microcracks were initiated around the middle stage of the fatigue test, the intensityalso showed a nonlinear response. The potential of anthracene-based mechanophorefor early damage detection in GFRP under complex loading was observed.