Yarn-level modeling and simulation of fancy weft-knitted fabric

Weft-knitted fabric is formed by interlocking loops, which results in an unstable and easily deformable structure. In particular, fancy weft-knitted fabric exhibits diverse structural variations and uneven distribution, leading to more prominent characteristics of instability and deformation. Achieving the desired pattern effect and dimensions often requires drawing multiple designs. In this work, to obtain the geometric model of fancy fabric, mesh-loop models with movement vectors are established based on the basic structure of four stitch types: plain stitch, tuck, float, and loop transfer. The cubic Catmull–Rom spline curves are used to fit the geometric centerline of the yarn. The movement vectors are used to represent the changes in the position of the key points of the standard loops in the fancy fabric, which are derived from the analysis of the pattern grid. A physical model is established based on the force analysis of the yarn, and the positions of yarn control points are determined by solving the Euler–Lagrange dynamic equations. Through iterative calculations, the deformation effects of the fabric are obtained, enabling the simulation of fancy weft-knitted fabric. The proposed algorithms were implemented using Visual C++. The reliability and accuracy of the simulation method are demonstrated by comparing the contours of the simulation results with the actual samples.