Maximizing the out-of-plane-permeability of preforms manufactured by dry fiber placement

Abstract Dry fiber placement (DFP) is a technology which enables outstandingly high mechanical performance of composite parts as preform structures with load-related fiber orientations can be created with minimum of fiber crimp. Furthermore, DFP has high cost-saving potential due to minimum material wastage during production. Recently, the efficiency has been further improved using an online binder application system, allowing the direct usage of untreated rovings instead of pre-designed rovings with binder applied by the manufacturer. Nevertheless, the poor impregnation behavior of DFP-preforms during liquid composite molding processing methods remains a main challenge. Encouraging an out-of-plane impregnation, e.g. by using a vacuum-assisted or compression resin transfer molding process, reduces the flow length within the preform and is a first step toward reducing cycle times. However, further improvements are required in order to apply DFP-preforming methods in serial production. Within this study influences on the out-of-plane permeability of DFP-preforms were investigated. The considered parameters were related to the material (e.g. binder amount) as well as the layup process and subsequent process steps.