Theoretical prediction of the needle penetration force in denim fabric part 1

Abstract

Purpose – The purpose of this paper is to theoretically calculate and predict the needle penetration force (NPF) in woven denim fabrics with twill 3/1 weave pattern, based on the geometrical, physical, and mechanical properties of fabric and constituent weft and warp yarns. Design/methodology/approach – In order to calculate the NPF by mathematical relations, the suggested model by Stylios and Xu (1995) is extended. While the needle penetrates into the fabric, the NPF is calculated on the basis of yarn tensile elongation, needle profile shape, and friction between needle and yarns. To accurately evaluate the developed model, nine different commercial denim fabric samples with various weft densities and linear density of weft yarns are produced, also five needles with different sizes are utilized. The NPF is measured in the successive cycle loading conditions similar to sewing machine process by using a designed and constructed instrument, which mounted on the Instron tensile tester. Findings – Comparing the predicted and experimental values indicated that the accuracy of model to predict the NPF is partly acceptable (R2=0.734). To improve the developed model, in addition to the forces which applied on needle due to yarn elongation, the other forces such as friction between weft and warp yarns, and yarn resistance to bending in the near of the sewing needle, which resist against needle penetration, can be considered. Originality/value – The fabrics with twill weave pattern have a complicated structure than plain pattern, therefore, in this paper the NPF of denim fabrics with twill 3/1 weave pattern were theoretically calculated based on yarn elongation. The spacing between centers of yarns in these fabrics is obtained by deriving a new formula. The NPF is measured on the Instron tensile tester to simulate sewing process.