纬编针织物几何建模及其算法

Modelling and algorithm of weft knitted fabric

为更真实地模拟纬编针织物几何形态,丰富细节特征,采用三层纤维螺旋的加捻纱线模型刻画针织物中纱线形态。将最小旋转标架作为计算加捻纱线中各纤维位置的局部坐标,通过几何变换、坐标变换等方法,构建任意曲线为中心线的加捻纱线模型。根据成圈、集圈、浮线3种典型纬编针织物线圈结构,通过反算法求取3次非均匀有理B样条曲线控制点,进而构建线圈纱线中心线模型。在此基础上,提出根据结构意匠图构建加捻纱线针织物几何模型的算法,并给出相应算例。结果表明:本文算法所建立的加捻纱线针织物几何模型保留了纱线加捻的细节特征,外观更加贴近真实织物。

For more real simulated effect and enrichment of details of weft knitted fabric geometry,this paper models the fabric at the scale of fibers.A three-layer spiral fiber structure of twisted yarn model was established for yarn geometry of weft knitted fabric.Rotation minimizing frames were regards as local coordinates for calculating fibers positions.A yarn model was established based on the methods of geometric and coordinate transformation,which had arbitrary curved center line.According to three basic knitted fabric structures of knit,tuck and float,three typical structure units of weft knitted fabric were constructed with non-uniform rational B-Splines,which were obtained with calculated control points.Finally,an algorithm for building a geometric model of weft knitted fabric using twisted yarns based on the structural notation was proposed.A sample using the algorithm was shown.The geometric model of weft knitted fabric with twisted yarn established according to the algorithm in this paper has remained details of yarn twisting,which looks closer to the real fabric.