From geometrical modelling to simulation of touch of textile products - open modelling issues

The touch of textile products is a complex process, depending on the interaction between the human finger and the textile product. The evaluation of the touch, or so named handle properties is complex process, requiring samples, testing humans or special testing devices. The numerical evaluation of the surface is until now not reported, because of the complexity of the textile products. This work presents the current state of the 3D modelling of textile products at yarn and fiber level and the required additional steps in order these models to get applicable for numerical simulation of the fabric touch. This work cover only the aspects related to the textile representation and do not include the modelling of the human finger as mechanical and receptor system during the interaction.Die Berührung und der Griffevaluation von Textilprodukten sind komplexe Prozesse, die von der Interaktion zwischen dem menschlichen Finger und dem Textilprodukt abhängig sind. Die Bewertung der 'Touch'- oder so genannten Griffeigenschaften ist ein komplexer Prozess, der Proben, Testpersonen oder spezielle Testgeräte erfordert. Die numerische Simulation der Oberflächenbeschaffenheiten ist aufgrund der Komplexität der textilen Produkte bisher nicht bekannt. Diese Arbeit stellt den aktuellen Stand der 3D-Modellierung von Textilprodukten auf Garn- und Faserebene und die erforderlichen zusätzlichen Schritte vor, damit diese Modelle für die numerische Simulation der Haptik von Textilien eingesetzt werden können. Es werden nur die Aspekte abgedeckt, die sich auf die Darstellung der Textilien beziehen und beinhaltet nicht die Modellierung des menschlichen Fingers als mechanisches und rezeptives System während der Interaktion

Numerical Simulation of Joining Ropes by Sewing Stitches

Braided structures are widely used in numerous contexts including everyday practice. In most cases, rope ends are knotted to form various types of loops or tie them to rigid body parts; however, knots take up space that may not be available in some application scenarios, thus making them unsuitable for certain purposes. Hence, this paper introduces first development steps of a method for the numerical simulation of rope ends connected by sewing stitches

Möglichkeiten der TexMind Software für die Generierung von textilen Strukturen für FEM Simulationen und CAD Anwendungen

Objekte der Simulation sind textile Strukturen - Geflechte, Maschenwaren und Gewebe. Diese können als Seile, tragende und deckende Strukturen in der Architektur, Bekleidung, im Medizinbereich usw. verwendet werden. TexMind Software beinhaltet mehrere Tools für die Generierung der Geometrie von textilen Strukturen und die Durchführung von einzelnen Berechnungen und Simulationen. Beispiele aus den Bereichen Flechten und Maschenware werden gezeigt. Neben den Vorteilen und der Möglichkeiten wird auch eine kritische Übersicht der offenen Punkte dargestellt. Möglichkeiten für Export zu FEM, CFD und CAD Software und solcher für Computer-Animationen werden demonstriert

Simulation of injection and capture of beam electrons in small-size betatrons by the method of macroparticles

The simulation problem of self-consistent dynamics of electron beam in small-size betatrons has been considered. The description of numerical model developed on the basis of macroparticle method is presented. The results of process modelling of electron injection and capture on the acceleration mode in betatrons with axially-symmetrical and asymmetrical magnetic field are shown. Optimal input injection parameters by beam current and energy (20...40 keV and 0,1...1,0 А) providing the maximum number of the capture electrons are defined. The techniques of increasing capture efficiency due to using variations of external magnetic field and additional energy selection of circuital decelerating EMF of the captured electrons are numerically studied. It allows an increase in capture coefficient from 4 to 7,4 % and capture at the acceleration up to 7,4·1010 electrons

Digital approach to studying of sign language movements in order to improve clothing design

Research of typical sign language poses was carried out to further use the obtained information in the processes of functional clothing design

PATTERN RELATED ISSUES IN THE MODELLING OF DEFORMED OVER SURFACE WARP KNITTED STRUCTURES WITH LONGER UNDERLAPS

The yarn level modelling of warp knitted structures is a complex process. For structures placed on the plane, it is well investigated and there are a few software solutions and papers reported. This paper considers the simulation of warp knitted structure, deformed in the 3D space. Especially the modelling of the areas of high curvature are detailed observed. Underlaps with longer lengths makes an unreal visualization for simulation results. Different pattern with different length of the underlaps are modelled with original algorithm developed by the authors. Modelling and visualization problems in the areas with long underlaps are discussed and possible solutions are proposed

Evaluation and optimization of textile ultrasonic welds for textile temperature control elements using transient thermal numerical analysis

Ultrasonic welding is an efficient method of joining thermoplastic fabrics or other textile semi-finished products in a watertight manner. It is applied in the making of functional clothing, such as chemical protective clothing, sportswear or smart clothing, or other technical products. Another special field of application developed at the Chair of Development and Assembly of Textile Products is the use of coated textiles as temperature control elements. For this type of product, it is necessary to design the ultrasonic welds in such a way that the media-tight coating is not damaged and the joint is continuous. This paper presents the option of evaluating and optimizing the ultrasonic welding process for the production of the textile tempering systems using transient thermal analysis in order to improve the overall quality of the seam and ensure media tightness along the seam. In the following article, the status of the welding process, in particular the ultrasonic process, the textile materials, the heating of the textile and the joining process of welding is presented. In addition, the transient heat flow through the textile is investigated with the aid of FEM methods; taking into account, various seam structures

Curvature change of moving bodies and its application for development of protective elements for protective clothing

When the human body moves, the body curvatures always change on the corresponding parts of the body. For ideal protective clothing, body curvatures during different movements have to be taken into account, as they influence the protection and the wearing comfort. For this reason, this study will focus on demonstrating methods to visually display such curvature changes. The changes are visually shown in different poses. The aim is to use this method to optimize protective elements on body parts with increased curvature changes. This would make protective clothing safer and more comfortable to wear

Possibilities for qualitative evaluation of the protection area of protective clothing

Protective clothing, worn for example by police, ambulance and private security services, has the task of protecting against weapon attacks and is becoming increasingly important. International standards specify test methods to ensure the protective effects and classes, but the protective surfaces or the wearing comfort are not defined more detailed in the standards. In the study, a new measurement method is developed and presented for determining the percentage of protected body parts by a stab protective vest. After considering various approaches, the combination of scanned 3D/4D body data and appropriate processing turned out to be the most suitable. With the developed method, the projection of protective surfaces onto scanned bodies or avatars is possible. This study helps defining a key indicator of the protected areas and therefore makes different vest variants more comparable

Investigation of the geometry changes of body legs with compression stocking in static position

The high speed (4D) body scanning provides technical possibility for accurate measurements of the body geometry and can be applied not only for moving objects, but as well for evaluating the changes of static geometry with time. This information is important for compression socks, because it provides data regarding the relaxation processes of the textile product and of the human leg. In this work, changes of the body geometry after 1 and 4 hours with compression socks are investigated. Up to 9% changes of the cross section areas and up to 5.5% of changes of the circumference between the position at the starting point and after 4 hours are detected. Additionally the differences between the both legs of the investigated person and of the different (upper- and bottom) part of the leg are observed. It is the first step to the digitalization of the personal compression stocking design