四步法三维编织预制件的渗透率

采用径向法测量了三维编织预制件的渗透率, 利用修正注入半径的循环方法, 基于Visual C + + 计算了渗透率的大小, 主渗透率方向分两步确定: 一是通过选择阈值的图像处理运算提取流动前沿; 二是采用Matlab中的非线性最小二乘法将所得轮廓进行椭圆拟合, 并计算该椭圆长轴方向与编织方向的夹角。结果表明: 编织参数影响渗透率, 当编织角一定时, 随着纤维体积含量的增加, 主渗透率降低; 当纤维体积含量一定时, 随着编织角的增加, 主渗透率降低, 但主渗透率的方向不随编织角的变化而改变, 始终保持与编织轴向一致。 

Permeabil ity of the 4-step 3D braided preform

Permeability of the three-dimensional braiding preform was measured by radial flow techniques.The permeability values were calculated by an iterative approach of the modified inlet radii.These iterations are conveniently performed based on a procedure with Visual C++.The orientation of the principal permeability tensor was(obtained) according to the following steps.Firstly,the flow front was extracted via an image processing algorithm of selecting a threshold.Secondly,the flow front ellipse was fitted by using the nonlinear least squares curve fitting(algorithm) in Matlab.The orientation between ellipse major and braiding axes was calculated in Matlab.The results show that braided parameters influence the permeability.The principal permeability decreases with increasing the(fiber) volume fraction when the braiding angle is constant,and it also decreases with increasing the braiding angle when the fiber volume fraction is constant.However,the orientation of the principal permeability does not vary with the braiding angle,and it keeps on coinciding with their braiding direction.