A study of thermo-viscoelastic compaction of prepregs and void formation during out of autoclave manufacturing of composite aerostructures

Abstract

In prepregs' manufacturing processes, different challenges are faced in order to understand and predict the behavior of prepregs throughout the manufacturing cycle. The OOA process has become more popular than the autoclave process due to its reduced cost. The OOA process involves the application of heat and low compaction pressure of only 1 atm. However, due to its low compaction pressure, the OOA process results in more air entrapment and void development. Prepregs exhibit a viscoelastic behavior. Therefore, the compaction-relaxation response at different compaction rates and fiber volume fractions plays a key role in understanding the viscoelastic response of uncured prepregs. Hence, this study characterizes the time-dependent behavior of un-cured 4-layer prepregs subjected to compaction-stress relaxation test at different displacement rates i.e., 0.1 mm/min, 1.0 mm/min, and 10 mm/min, at 0.65 fiber volume fraction and allowed to relax for two hours. Also, a study following the same procedure focused on understanding the effect of temperature variation (25,35,45, and 55 °

Date of Award	Nov 2021
Original language	American English