纺织复合材料预制件多层机织布内气泡形成机理

以多层机织布为对象,首先基于两个分别对应于两种典型叠加模式的单元结构模型,通过理论分析,建立了多层机织布纵向切面内气泡形成的分析模型;然后采用有限元-控制体积方法对单元结构内树脂的扩散及气泡形成的过程进行了数值模拟。理论分析和数值模拟的结果符合一致,均表明:不同局部区域差异很大的渗透系数是气泡形成的最根本原因,而纬线的轴向渗透系数和经线的横向渗透系数之比对多层机织布纵向切面内气泡的形成及尺度起着决定性的作用。

MECHANISM OF VOID FORMATION IN TEXTILE PREFORM-MULTI-LAYER WOVEN FABRICS

The void formation during RTM processing seems to be inevitable and the presence of voids has a deleterious effect on the mechanical properties of textile composites. The purpose of this study is to investigate the mechanism of void formation in multi-layer woven fabrics. Two unit cell models were suggested to represent the cross sections of multi-layer woven fabrics with two typical layering patterns. Based on these two geometrical models, an analytical model was developed to describe the mechanism of void formation during RTM processing. The flow fronts and void formation in these two cells were also numerically simulated using a control-volume method. The simulated results agree well with those predicted by the analytical model. The results show that, for a given fiber preform, the ratio of the weft axial permeability Kab to the warp transverse permeability Ktb is responsible for the size of the void.