Out-of-autoclave molding of carbon fiber laminates by consolidation with shape memory polymer foams

Abstract

Carbon fiber reinforced (CFR) laminates have been manufactured by an innovative out-of-autoclave (OOA) process thanks to the use of smart materials. In this study, for the first time, a shape memory polymer (SMP) foam has been used into a pressure dome to apply the consolidation pressure to the laminate. Heat for resin curing was supplied by a thermal blanket between the laminate and the SMP foam. In order to test the OOA molding process, 24-ply CFR laminates were manufactured and tested. For comparison and reference, CFR laminates were also molded by traditional vacuum bagging and autoclave curing. Samples for bending tests were extracted from OOA and autoclave molded plates. Results show that the SMP-OOA process is able to provide optimal laminate consolidation, despite of the low applied pressure (about 1 bar). A comparable density and ply thickness was measured on samples by the innovative and the conventional molding process, whereas a higher bending strength (+5%) was found on OOA samples. A higher dispersion was also observed for the properties of SMP-OOA molded laminates in comparison with autoclave, probably due to the prototyping nature of the molding technique in comparison with the well-known autoclave practice. Nevertheless, the final quality of the molded laminates is very high, and the SMP-OOA process is a very promising candidate as a technology to repair CFR structures.