Influence of stitch length and structure on selected mechanical properties of single jersey knitted fabrics with varying cotton percentage in the yarn
Knitting is a process of manufacturing a fabric by the intermeshing of loops of yarn. Knitted fabric possesses high stretch and recovery, providing greater freedom of movement and outstanding comfort qualities for which they have been preferred as fabrics in many kinds of clothing for a long time. In clothing design and manufacturing, fabric characteristics are usually dictated by a specified end-use.1,2
AN INVESTIGATION ABOUT BEHAVIOR ON THE WEAR PERFORMANCE OF MATTRESS FABRICS
: In this experimental study, it is investigated, comparatively, the effect on abrasion resistance of the presence of different type of yarns in the structure of knitted fabrics, used for mattress covers. The most significant problem is abrasion wear, which reduce the product 's life and quantify the fabric’s durability under repetitive friction. Complex knits, with various fibrous compositions, and different masses, were subjected to rubbing wear, tested on the NU-Martindale device, then the samples were microscopically evaluated. The results demonstrated the influence of raw material and the number of friction cycles until the material fails. The polyester and viscose textile support showed the highest friction wear resistance. There were presented: the samples subjected to tests, the decrease of the abrasion resistance after the friction tests, the microscopic aspects and the mass loss of the degraded samples. Future studies will also investigate other physico-mechanical characteristics of these types of products with the most demanding requirements that offer high durability and performance.
Numerical analysis of surface crack propagation in flexible pavements using XFEM and cohesive zone model
Surface initiated (top-down) cracking in the longitudinal direction of pavements has become a predominant mode of failure in thick asphalt pavements. Most previous researchers studied crack propagation using the traditional Linear Elastic Fracture Mechanics (LEFM) method by calculating the stress intensity factor around the crack tip. In this paper, Extended Finite Element Method (XFEM) was used to study the key factors causing surface initiated crack propagation under surface tension and/or shear. A two-dimensional (2-D) finite element (FE) model for a two-lane flexible pavement was built to predict pavement responses and crack propagation potential under various scenarios. It was found that surface tension is the major driving force for crack propagation when the crack is at some distance away from tire loading. The results show that the distance from the location of crack to tire loading, the depth and direction of the crack, and the modulus ratio between the hot-mix asphalt (HMA) layer and the base layer have significant influences on crack propagation under surface tension. On the other hand, this study shows that shear stress can induce surface initiated crack propagation near the loading area as the shear resistance of material becomes low at the high temperature.