Abstract:
Knitted fabrics are widely used in clothing because of their distinctive
ability to be shaped and formed, which is fundamentally different from the
behavior of woven cloth. Since stitches produce complex interactions between
yarns, the macroscopic behavior of knitted fabrics depends more on their
loop structure and stitch patterns than on the physical properties of the
yarn. In order to explore the unique mechanical properties of knitted
textiles we have developed a yarn-level model for weft-knitted fabrics that
can be used in Finite Element Analysis (FEA) simulations. Producing
geometric models of yarns in a knitted material is framed as an optimization
problem. In this computing context, a single “cost” function is defined that
captures the various required features of the final geometric model. The
function is specified in such a way that finding the variable values that
results in a minimum function evaluation produces the desired geometric
result. The centerlines of the fabric's yarns are defined as Catmull-Rom
splines, and the cost function is minimized 33 by adjusting the locations of
the spline's control points. The optimization is based on physical
parameters such as yarn interpenetration, length of the yarn and bending
energy. The optimized models are written to a file which can be directly
read by an FEA software. The results show that our approach can create
yarn-level models of weft-knitted fabrics consisting of an arbitrary pattern
of knit and purl stitches, with a range of sizes, that are suitable for FEA
simulations.
