Hybrid composites allow designers to develop efficient structures, whichstrategically exploit a material’s strengths while mitigating possible weaknesses.However, elevated temperature curing processes and exposure to thermally-extremeservice environments lead to the development of residual stresses. These stressesform at the hybrid composite’s bi-material interfaces, significantly impacting thestress state at the crack tip of any pre-existing flaw within the structure and affectingthe probability that small defects will grow into large-scale delaminations. Therefore,in this study, a carbon fiber reinforced composite (CFRP) is co-cured with a glassfiber reinforced composite (GFRP), and the mixed-mode fracture toughness ismeasured across a wide temperature range (-54°C to +71°C). Upon completion of thetesting, the measured results and observations are used to develop high-fidelity finiteelement models simulating both the formation of residual stresses throughout thecomposite manufacturing process, as well as the mixed-mode testing of the hybridcomposite. The stress fields predicted through simulation assist in understanding thetrends observed during the completed experiments. Furthermore, the modeledpredictions indicate that failure to account for residual stress effects during theanalysis of composite structures could lead to non-conservative structural designs andpremature failure.
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