Composite-bonded steel substrate with silyl-modified polymer exposed to thermal distress

This paper discusses a research program examining the residual performance of carbon fiber reinforced polymer (CFRP)-steel interface bonded with an emerging adhesive called silyl-modified polymer (SMP) when exposed to elevated temperatures from 25°C to 200°C. Double-lap tension specimens are prepared and conditioned at predefined temperatures for three hours. Test results reveal that interfacial capacity is preserved up to a temperature of 100°C. Thermally-induced capacity degradation is, however, observed for the specimens exposed to temperatures beyond 100°C. A phase-transition is noticed in adhesive morphology during heating at temperatures higher than 175°C, which affects the adhesion properties of the SMP. The development of CFRP strain is influenced by geometric discontinuities along the interface. Fiber disintegration dominates the failure of the interface exposed up to 150°C, including local fiber dislocation and partial CFRP pull-out. CFRP-debonding is, however, the primary failure mode for the specimens exposed to a temperature higher than 175°C. The Bayesian updating method is used to probabilistically infer the response of the CFRP-steel interface.