An experimental study was undertaken to investigate the face sheet/core debond fracture toughness of E-Glass/Vinylester facesheet, Divinycell H130 closed-cell PVC core, sandwich composites. The 46 cm x 60 cm sandwich composite panel had a core density of 130 kg/m~3 and was fabricated by the VARTM (Vacuum Assisted Resin Transfer Molding) process, then machined into 2.54 cm x 20.32 cm specimens for Mode I interfacial fracture toughness from double cantilever beam (DCB) tests. To determine the effects of a marine environment (temperature and sea-water) on conditioned specimens with a debond present, a debond crack was induced prior, as well as subsequent to, 5000 hours of elevated temperature (80°C), elevated temperature and moisture (80°C, 90% + relative humidity), and sea-water (submersed) conditioning. The Mode I interfacial fracture toughness from room temperature DCB tests for each debond arrangement and environmental condition was then compared using the critical strain energy release rate (SERR). The critical values of SERR can be considered the fracture toughness of the sandwich material, G_(IC). The G_(IC) was reduced considerably (greater than 50%) in specimens submerged in sea-water, and significantly (approximately 90%) due to 5000 hours of the 'hot/wet' and 'hot/dry' exposure. Results showed that elevated temperature exposure contributes greatest to the PVC core degradation, whereas sea-water exposure mostly degrades the facesheet/core interface. Exposure to elevated temperatures, along with inducing cracks between the facesheet and a PVC core degraded by elevated temperature exposure, appear to be the most detrimental to Mode I fracture toughness.
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