基于离散元-有限元联合算法的纤维流场变形行为

Deformation behavior of fiber flow field based on discrete-finite element algorithm

纤维在气流中的动态特性对织物的结构和性能有着决定性的影响。为研究柔性纤维在纺织各环节不同流场下的转移变形演化过程,采用计算流体动力学(CFD)数值模拟方法构建了在空间各向位置存在速度差异的特征流场分布,并在此基础上构建了离散元多球链柔性纤维模型,利用欧拉-拉格朗日法耦合求解自由纤维的运动轨迹,并讨论了其在差异流场中的受力情况与转移变形行为。结果表明:纤维初始取向角度会影响弯曲效果,随着纤维主体与气流方向的夹角增加,纤维越容易呈现弯曲形态;不同的纤维喂入位置会影响气流累积作用,纤维端之间所受气流力的差值越大,累积作用时间越长,纤维的弯曲效果越显著;纤维间的交互作用会使纤维簇发生分层现象,不利于多数纤维的混杂与弯曲变形。该研究揭示了单根柔性纤维和纤维簇在流场中的弯曲变形机制,提供了研究纤维在复杂流场中运动和变形的有效方法,可以为改善纺织工艺提供指导。

The dynamic characteristics of fibers in airflow affect the structure and performance of fabrics.In order to study the deformation behavior of flexible fibers under the flow field,CFD numerical simulation was used to explore the flow field distribution with velocity difference.Furthermore,the discrete element flexible fiber model was established using the coupled Euler-Lagrange method.The fiber trajectory was presented and its force and transfer deformation behavior in the differential flow field was discussed.Results show that the initial orientation angle of the fiber affects the bending effect.The increase of the angle tends to bend the fiber.The fiber feeding position affects the cumulative effect of airflow.The bending effect of fibers becomes more significant when the difference of the volume force of airflow force between fiber ends gets larger and the cumulative effect time is longer.Fiber interaction intensifies the delamination of fiber clusters,which is not conducive to the mixing and bending deformation of fibers.