Modelling of knitted fabric deformation
The objective of this study was to investigate new models for the mechanical behaviour of knitted fabrics in quasi-static deformation from an initiallyrelaxed state to the extended state. In order to do so a mechanism for plain knitted structure deformation in plane was proposed, implemented and tested on a range of real samples. The problem of extension of a knitted structure is complicated by the combination of non-linear properties derived from both the characteristics of the knitted structure and the properties of the yam. To obtain a solution to this problem a finite-elementtechnique was used to evaluate the proposed model. The proposed model of mechanical behaviour of knitted fabrics is an analogue of the thin membrane problem in mechanics. The model developed is applicable to a wide range of mechanical problems where it is possible to assume that fabric is a thin membrane with zero bending rigidity. To facilitate the mechanical properties of the proposed model, standard dimensional parameters of fabric and yam combined with the mechanical properties have been used. With the purpose of obtaining important yam characteristics for the subsequent evaluation of the model, an advanced analysis of the yam path in plain knitted fabric was performed. An algorithm for loop geometry from the given fabric dimensions in course and wale directions and yam properties were developed. In order to implement the algorithms developed during this investigation complex software was written. This software allows simulation of the mechanical behaviour of different plain knitted structures under various loading and boundary conditions. At the approval stage of the model, a number of fabric samples were produced and tested; models of real samples have been simulated and compared with experimental data. The model used could be developed further to extend the application to tackle complex 3D deformation and to simulate a range of different knitted structures.