DEVELOPMENT OF A PARAMETRIC SURFACE MODEL OF RIB 2X2 KNITS

Abstract

This study aims to develop an algorithm for constructing surface models (macro-models) of rib knitted structures, for three-dimensional modeling of tensile deformations in coursewise direction and predicting the physical and mechanical characteristics of knitted fabrics and products. During the research, methods of theoretical analysis, spline theory, computer graphics, programming tools have been used. As a result of the research, it was found that for modeling of some physical and mechanical characteristics of knitted rib structures in a deformed state, it is advisable to use geometric models that reproduce the geometry of the knitted fabric surface with high accuracy, but do not have detailed structure at the level of fibers and threads. If necessary, the values of air permeability, thermal conductivity and others porosity for such models can be taken into account under the form of appropriate indexes. At the same time, to calculate the coefficients of porosity and air permeability, one can use both experimental data and 3D models with a higher detailed structure of the textile material (meso-model). In the course of research a set of geometrical characteristics of samples of rib knits patterns is formed. Samples of 2x2 rib knits of PAN yarn of 31х2 tex have been made with a flat bed knitting machine of 10th gauge. The samples were suspended in the clamps of the relaxometer type "rack" and loaded with weights weighing from 20 to 120 g with an interval of 20 g. By means of the camera, the geometrical characteristics of the knitted surface in dry-relaxed state and in 6 discrete tensile states were recorded and determined. According to the obtained data, parametric 3D models of the knitted surface were built. An algorithm for constructing a macromodel of knitted rib 2x2 structure in the process of stretching in the coursewise direction, taking into account the peculiarities of the situational change in the geometry of the thread within the report has been developed. Three-dimensional parametric models of knitted surface (macro-models) of knitted 2x2 rib structures in the Autodesk Inventor environment have been created.