基于数字图像技术的纤维织物面内渗透率表征

材料渗透率的表征受其结构空间离散性和求解方式准确性的严重影响。基于数字图像技术，评估了纤维织物渗透率的空间分布，并探讨了阶梯铺层对灌注工艺的影响。首先，从恒压单向注射实验的视频流中动态提取了流动前沿的流速分布和流动前沿角，通过织物渗透率与结构的关系仅一次实验便可求得纤维织物的面内局部渗透率分布；其次，利用正态分布函数拟合，建立了基于数字图像技术的纤维织物面内主方向渗透率张量的求解方法，并利用该方法研究了编织形式对渗透率的影响；最后，研究了阶梯铺层和恒定铺层对灌注过程的影响。结果表明:建立的基于数字图像技术的渗透率表征方法可以通过一次实验同时获取面内主方向上的渗透率及其空间离散型；在恒定铺层下缎纹织物渗透率随着纤维层数增大而增大，从厚铺层向薄铺层的灌注方式可以达到最优的灌注时间。 

In-plane permeability characterization of fiber fabric based on digital image technology

The spatial discretization of the structure and the method’s accuracy have profoundly affected the characterization of material permeability. The spatial distribution of fabrics’ permeability was evaluated based on digital image technology, and the effect of step layup sequence on the infusion process was discussed. Firstly, the flow velocity distribution and the flow front angle of the flow front were dynamically extracted from the video stream of the constant pressure unidirectional injection experiments. The in-plane local permeability distribution of the fiber fabric can be obtained through only an experiment by the relationship between fabric permeability and structure. Secondly, solving method of the permeability tensor in the main direction of the fiber fabric based on digital image technology was established by fitting the normal distribution function and was used to study the influence of the weaving form on the permeability. Finally, the step layup sequence and constant layup sequence on the infusion process were studied. The results show that the in-plane permeability characterization method established based on digital image technology could simultaneously obtain the permeability in the main direction of the plane and its spatial discretization through only one experiment. The permeability of satin fabric increases with the increase of the number of fiber layers. The infusion method from thicker region to the thin region can achieve the optimal infusion time.