结构化增韧层增韧RTM复合材料预成型体的渗透特性

选用尼龙无纺布(Polyamide Nonwoven Fabric,PNF)作为结构化增韧层,研究了增韧层的引入对纤维预成型体在树脂传递模塑成型(RTM)工艺过程中渗透特性的影响。结果表明:在径向非饱和流动模式下,层间增韧预成型体沿纤维方向的渗透率为5.2×10-12 m2,略低于非增韧预成型体的7.1×10-12 m2,而沿垂直于纤维方向的渗透率为2.3×10-12 m2,略高于非增韧预成型体的1.6×10-12 m2。此外,层间增韧预成型体的单向饱和流动渗透率为2.6×10-12 m2,较非增韧预成型体的1.9×10-11 m2下降了约1个数量级,z向饱和流动渗透率较非增韧预成型体的1.3×10-13 m2下降至2.5×10-14 m2,同样下降了约1个数量级。对复合材料层间微观形貌的分析结果表明:造成预成型体渗透率下降的主要原因首先是PNF引入至层间之后将阻碍层间树脂的快速流动,同时增韧层将使层内纤维含量明显升高,由55.3vol%上升到63.7vol%。

Permeability of toughened RTM composite preforms by structural toughening layer

The nylon nonwoven fabric (Polyamide Nonwoven Fabric, PNF) was selected as structural toughening layer to investigate its effect on the permeability of fiber preforms during resin transfer molding (RTM) process. Results show that under unsaturated radial flow pattern, the permeability of the interlaminar toughened preform along the direction of fiber (5.2×10^-12 m²) is lower than that of the untoughened preform (7.1×10^-12 m²). On the contrary, the permeability of the toughened preform perpendicular to the fiber direction (2.3×10^-12 m²) is higher than that of the untoughened preform (1.6×10^-12 m²). Moreover, the unidirectional saturated flow permeability of interlaminar toughened preform is 2.6×10^-12 m², which is much lower than that of untoughened preform (1.9×10^-11 m²), decreased by an order of magnitude. The z -directional saturated permeability also dramatically decreases from 1.3×10^-13 m² (untoughened preform) to 2.5×10^-14 m², decreased by an order of magnitude. The interlaminar morphology analysis results reveal that the decrease of the permeability of preform mainly results from the inhibition of rapid flow of resin, introduced by PNF as structural layers and the increment of interlaminar fiber contents rising from 55.3vol% to 63.7vol%.