树脂传递模塑成型工艺中嵌套效应引起渗透率变异的实验与数值模拟

Experimental and numerical simulation of permeability variation induced by nesting effect in resin transfer molding

树脂传递模塑成型工艺(RTM)中最重要的变形模式之一是厚度方向压缩。厚度方向压缩减小了织物预成型体的厚度,使织物预成型体局部结构形式发生改变从而引起嵌套效应。嵌套效应不仅会减少织物预成型体的厚度,增加纤维的体积分数并改变孔隙率,而且相邻织物层嵌套效应具有一定的空间分散性,从而使得织物预成型体渗透率具有变异性。本文针对低黏度树脂设计了一种实验装置用以测量局部渗透率的空间分散性,随后建立了随机嵌套单胞模型,利用ANSYS/CFX有限元软件实现了单胞填充浸润的数值模拟,通过流量分析获得局部渗透率,并研究了渗透率的统计分布。通过实验结果与数值模拟结果相对比,验证数值模拟结果的可靠性。最后,基于渗透率的统计分布建立了随机渗透率场,并进行填充浸润的数值模拟,通过与传统恒定渗透率的方法进行比较,证明该方法具有更高的先进性。研究结果可以对未来RTM工艺的稳健性优化提供依据。

One of the most important deformation modes in resin transfer molding(RTM)of manufacturing processes is compression along thickness direction,which reduces the thickness of the textile preform and causes the change of the fabric structure,causing the nesting effect.Nesting reduces the laminate thickness,increases the fibre volume fraction,and changes the porosity pattern.The effect of adjacent fabric layer nesting has a certain spatial dispersion.This makes the fabric permeability variable.In this work,an experimental device was designed to measure the spatial dispersion of local permeability for low viscosity resins.Then,a random nested monocyte model was established,ANSYS/CFX finite element software was used to realize the numerical simulation of single cell,and the local permeability was obtained by flow analysis.The statistical distribution of permeability was then studied.The experimental results were compared with the numerical simulation results.The reliability of the numerical simulation results was verified.Finally,the random permeability field was established based on the statistical distribution of permeability,and the numerical simulation of resin filling was carried out.The results show that this method is more advanced than traditional method based on constant permeability.The results can provide a basis for the robustness optimization of RTM process in the future.