Approach to Optimizing a Combined Out-of-Autoclave (OOA) Prepreg/Liquid Composite Molding (LCM) Process for Integrated Structures

Hybrid processes combining characteristics of prepreg and resin infusion/injection techniques are interesting and advantageous solutions for manufacturing of highly integrated structures. The possibility, given by traditional prepreg technology, to manufacture with a good reproducibility parts having elevated mechanical performances and as well to introduce additives like flame retardants or tougheners, can be successfully combined with liquid composite molding (LCM) characteristics. This work aimed to investigate these combined processes. The present research involved furthermore out-of-autoclave (OOA) prepreg which provide additional cost-savings and environmental advantages compared with standard autoclave techniques: OOA prepreg plies and dry fabrics are laid up together in a mold and then resin is injected (RTM-like) or infused (VARI-like) in the cavity. When the impregnation is completed the part can be cured in oven. Goal of the investigation is to analyze the performances of hybrid laminates, in respect to pure OOA prepreg- and LCM-parts and to optimize the manufacturing route, assessing the process robustness through several tests. Simple demonstrators have been also realized to prove the hybrid technique feasibility and effectiveness.