基于数字单元法的三维正交织物微观几何结构建模

为了反映织物内部纱线的空间构型和微观几何结构,针对在织物建模过程中,因忽略纤维间的相互作用而引起的纱线截面形状变化的问题,基于数字单元法理论,提出了一种计算纤维间摩擦力的方法。通过纱线纤维化离散,用数值模拟和仿真方法模拟三维正交织物成型过程,建立了5种精度递进的微观几何结构数值模型。5种模型中的每根纱线分别由4、7、12、19和37根数字纤维表征。研究结果表明:随着纱线纤维化离散程度的提高,仿真时间延长,织物厚度减小,纤维体积分数增大,节点平均作用力下降速度变缓,势能变小;当每根纱线由19根数字纤维组成时,所建织物的微观几何结构数值模型与真实织物样本在显微镜下的内部切片图像较为吻合。

Micro-geometry modeling of three-dimensional orthogonal woven fabrics based on digital element approach

In order to reflect the configuration and micro-geometry of yarns inside the fabric and aiming at the problem of overlooking the change of cross-section yarn shape, which was caused by relative motion between fibers, during the simulation process, this paper proposed a method for calculating the inter-fiber friction based on the digital element approach. Based on this, the micro-geometry models of five three-dimensional orthogonal woven fabrics were built at sub-yarn scale with varied cross-sectional yarn shape via weaving process simulation. Each model is composed of 4, 7, 12, 19, and 37 digital fibers per yarn respectively. The results show that when the number of digital fiber per yarn increases, the simulation time and fiber volume fraction increases, the fabric thickness, the rate of the nodal force decline, and the potential energy decreases. When the number of fiber per yarn equals to 19, the micro-geometry of the numerical model is the most consistent with the microscopic picture of the actual fabric.