Iwona Frydrych

A New Approach for Predicting Strength Properties of Yarn

We present a new approach to yarn characterization and yarn tensile response based on fiber parameters such as strength and strain-at-break, length, and fineness. Yarn characterization is concerned with twist, linear density, and the ratio of experimental yarn unevenness to the Martindales limit characteristic for spinning mills. Experimental strength results are compared with predicted ones on the basis of theory.

Quantitative Evaluation of air gap Thickness and Contact Area Between Body and Garment

The thermal, evaporative and wicking properties of clothing depend not only on the properties of the fabric but also on the thickness of air layers and the magnitude of the contact area and their variation. The aim of this study was to accurately determine the contact area and the air gap thickness between clothing and the human body in detail. These parameters were measured for a range of typical patterns of garments (tight- and loose fitting) covering either the upper or lower body and made of various types of fabrics (knitted and woven). The method consisted of imposing three-dimensional scans of the nude and dressed manikin and determining the distance between their surfaces by advanced three-dimensional scan post-processing. Due to this method the distribution of the air gap thickness and the contact area over body parts was obtained and this knowledge can be applied in models of heat and mass transfer in the clothing.

Surface Frictional Resistance of Fabrics Woven from Filament Yarns

The differences in frictional forces acting between fabrics woven from filament yarns are dependent on the morphology of the fabrics and the rubbing direction. When one fabric is moved across a second stationary fabric and the projecting yarn waves of one of the fabrics is rubbed perpendicular to the yarn axes orientation, the Howells characteristics of frictional resistance for the fabric and yarn have similar values.

RELATION OF SINGLE FIBER AND BUNDLE STRENGTHS OF COTTON

A theoretical derivation of an equation for bundle strength is presented, assuming a normal distribution of single fiber strains. Unfortunately, the experimental fiber strain distribution cannot be considered as normal. Therefore, further theoretical con sideration involves the derivation of an equation for bundle strength assuming Ray leighs distribution of single fiber strains. Theoretical values of coefficients of cotton fiber strength efficiency in the bundle are compared with the experimental values obtained in our earlier work, and a satisfactory agreement is reached.

Static Tearing, Part II: Analysis of Stages of Static Tearing in Cotton Fabrics for Wing-shaped Test Specimens

We present here an analysis of the stages of static tearing in cotton fabrics for wing-shaped test specimens. For the analysis and measurements of geometry of the tearing zone, a program for image analysis was realized and video film elaborated. Moreover, the influence of the constructional features of woven fabrics and fabric structure, and also the testing conditions on the tear force and tearing zone parameters were examined.

Predicting the Nep Number in Cotton Yarn—Determining the Critical Nep Size

Neppiness is one of the most important aspects of cotton yarn quality and significantly influences the appearance of woven and knitted fabrics produced from that yarn. The direct sources are neps and trash contained in the cotton fiber sliver feeding the spinning frame. Nevertheless, not all neps cause yarn faults. For each yarn linear density, there exists a critical nep size above which neps are registered by an Uster tester as yarn imperfections. Determining the critical nep size is important from the point of view of predicting the nep number per 1000 m of cotton yarn. We consider and elaborate on theoretical models of critical nep size as a function of the linear density of cotton ring spun and OE yarns. On the basis of our equations, we calculate the critical nep size for different yarn linear densities. The experimentally obtained results confirm our theoretical models.

Static Tearing, Part I: Its Significance in the Light of European Standards

Static tearing is one of the most common types of failure in textile fabrics and determines the durability of an article. The tear resistance is the strength parameter, which characterizes the textile product with respect to its resistance to outer mechanical forces. In the presented work, we describe in detail the problem of static tear strength in woven fabrics. In the first part, the meaning of the tear strength in an assessment of textiles, particularly with reference to the present day, is presented.

Strength Properties of Cotton Blend Yarns

This paper discusses two methods of predicting strength properties of ring spun cotton blend yams produced using a normal technological process. Another facet of the research is the application of fiber parameters obtained on a high volume instrument ( HVI ) to the predictions. Fiber strength as measured by breaking individual fibers is higher than that measured on the HVI line using the bundle method, and the mean and mean ratio of these values is 1.34. The experimental results and the strength predictions are compared.

Comparative Analysis of the Thermal Insulation of Traditional and Newly Designed Protective Clothing for Foundry Workers

An objective of the undertaken research was checking the applicability of aluminized basalt fabrics for the production of clothing for foundry workers. The results of flammability, the resistance to contact, convective and radiation heat, as well as the resistance to big molten metal splashes confirmed the thesis of applicability of the packages with the use of aluminized basalt fabric content for the assumed purpose; therefore, such protective clothing was produced. Thermal comfort of foundry workers is very important and related to many factors, i.e., the structure of the protective clothing package, the number of layers, their thickness, the distance between the body and appropriate underwear. In the paper, a comparison of the results of thermal insulation measurement of two kinds of protective clothing is presented: the traditional one made of aluminized glass fabrics and the new one made of aluminized basalt fabrics. Measurements of clothing thermal insulation were conducted using a thermal manikin dressed in the protective clothing and three kinds of underwear products covering the upper and lower part of the manikin.

Analysis of lockstitch seam strength and its efficiency

Purpose – Seam efficiency plays an important role for obtaining a desired seam quality. Therefore, this issue is often referred in research papers. The purpose of this paper is to determine the seam strength and efficiency as well as examining, if and how such factors as: a kind of fabric, kind of thread, kind of seam and the stitch density influence the transverse seam strength and the seam efficiency. Design/methodology/approach – For research four types of polyester/wool fabrics having different structural parameters and two types of polyester sewing threads were used. Three types of seam were made. The fabric samples were sewn using lockstitch with three different stitch densities. Obtained in this way seams were tested on the tensile machine. The influence of individual factors on the seam strength and its efficiency was assessed statistically using a multivariate variance analysis (ANOVA). Findings – The findings of this study revealed that the independent variable – stitch density affect significantly of the seam strength as well as its efficiency. Seam strength and seam efficiency values increase with the increase stitch density. Moreover, the variance analysis showed that a kind of fabric also is a statistically significant factor for the seam efficiency and its strength. Furthermore, in the case of seam efficiency it is also important to the stitch direction. However, the study did not show an impact of kind of thread and kind of seam on dependent variables: the seam strength and its efficiency. Research limitations/implications – Due to the fact that this paper focuses on the seams made only on wool/polyester fabrics with two the most popular weaves, involving only two sewing PES threads, the conclusions presented in this paper are valid only to this assortment and cannot be generalized. Originality/value – So far, it has not been taken research on the effect of seams with the different number of sewn layers on the seam strength and efficiency. This issue has been taken in this work.