<p>When a composite laminate is transversely impacted by a projectile at the ballistic limit, its failure mode transits from global conical deformation to localized perforation. This Ph.D. dissertation aims to reveal the fundamental material failure mechanism at the ballistic limit to control perforation. First, transverse impact experiments were designed on composite strips to isolate the interaction between plies and tows. Three failure modes were identified, divided by no, partial, and complete failure before the transverse wave deformed the entire composite strip. The failure phenomenon and critical velocity region can differ with the fiber type and projectile nose geometry and dimension. In most impact events, the composite strips all failed in tension in the front of the projectiles, although they failed at different positions as the projectile nose geometry and fiber type changed. A special failure phenomenon was uncovered when the composite strips were impacted onto razor blades above the upper limit of the critical velocity region: the composite strips seemed to be cut through completely by the razor blades. To further investigate the failure by razor blade, a microscopic method was developed to cut a single fiber extracted from the composite strip and simultaneously image the failure process inside a Scanning Electron Microscope (SEM). The experiments revealed that the razor blade cannot cut through the inorganic S-2 glass fibers while can partially incision the aramid Kevlar^®KM2 Plus fibers and completely shear through the ultra-high-molecular-weight polyethylene (UHMWPE) Dyneema^® SK76 fibers. Further investigations on the fiber’s failure under dynamic cut revealed that there was no variation in the failure mode when the cut speed was increased from 1.67 μm/s to ~5.34 m/s. To record the local dynamic failure inside the composite strips and single fibers at high-velocity impact, an advanced imaging technique, high-speed synchrotron X-ray phase-contrast imaging, was introduced, which allows to capture the composite’s internal failure with a resolution of up to 1.6 μm/pixel and at a time interval 0.1 μs. Integrated with a reverse impact technique, such an advanced imaging technique is believed to be capable of revealing the mechanism involved in the impact-induced cut in single fibers, yarns, and composite strips. The relevant studies will be the extended work of this Ph.D. dissertation and published in the future.</p>

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Master of Science / Department of Apparel, Textiles, and Interior Design / Joy Kozar / Global apparel supply chains require collaboration from many sectors, including consumers, retail firms, manufacturing firms and factories. The role of sourcing agents as a facilitating sector of global apparel supply chains was explored as part of this study. A quantitative analysis of import data from the U.S. Department of Commerce for four apparel categories revealed changes in import volume over the last 10 years for all major trade regions of the world. Qualitative data was also collected to further analyze how industry professionals perceive the role of sourcing agents in facilitating apparel production movement. Participants revealed that sourcing agents breakdown cultural and geographic barriers between U.S. firms and off shore factories, providing a competitive advantage to U.S. apparel firms by reducing production cost and facilitating production of complex designs, but lack any form of formal regulation.

Master of Science / Department of Apparel, Textiles, and Interior Design / Sherry J. Haar / Inspired by people and objects of the late 1950s/early 1960s, textile patterns were created to use as a tool in the education of children through play. Four themes were developed, with three main prints in each theme. These twelve prints had a coordinating print and solid colors designed, and were utilized in the development of paper doll clothing. Representing the look of Jacqueline Kennedy, the paper dolls feature a pearl necklace, sunglasses, and a brunette hairstyle. Fabric was also printed on using a home-based ink jet printer, and used to construct a garment for an 18-inch, three dimensional doll. The final outcomes were exhibited in a display window, with an interactive element for adults and children at the opening reception.

L’industrie aéronautique est basée sur le compromis entre les performances et les prix. L’objectif principal est de réduire la masse dans le but d’augmenter le rayon d’action ou la masse utile. Ce document présente une façon innovante de concevoir des matériaux composites basée sur une nouvelle technologie textile et par conséquent une nouvelle stratégie de conception. Je vais me focaliser sur deux applications industrielles qui consistent à ajouter de nouvelles fonctions à des matériaux composites pour réduire le nombre de pièce et donc la masse globale. La seconde application est orientée vers les pièces aux surfaces non développables. Dans cette application, je montrerai comment il est possible d’ajouter des propriétés mécaniques à de nouvelles architectures textiles dans le but d’obtenir un meilleur rapport masse/performance. / Aeronautical industry is made of compromises between the performances and the costs. The main goal is to reduce the mass in order to increase either the flight range or the useful mass. This document presents the innovative way to design composite materials based on a new textile technology and as a consequence a new way of design strategy. I’ll focus on two industrial applications which consist in adding new features to composite materials in order to reduce the number of parts and so on the global mass. The first application is the conception of a thermally conductive composite material which could allow a new way to design on flight computers andelectronic devices. The second application is focused on the non developable shape parts. In this application, I’ll show how we have added mechanical properties to new textile architectures in order to obtain a better mass/performance factor.

In the present study, we have explored the role of brand trust and consumer brand identification in evoking brand forgiveness when individuals are exposed to communications related to corporate social responsibility (CSR) wrongdoings. Grounded in attribution theory, we have developed and empirically tested a conceptual model to assess the effectiveness of brand trust in facilitating the attribution of wrongdoings either internally (e.g., believing that the brand had wrong intentions) or externally (e.g., believing that there are other factors beyond the brand's control) in influencing brand forgiveness. We conducted an online experiment utilizing Amazon Mechanical Turk (MTurk) to recruit participants from the U.S. national population (N = 620) following a quota sampling method. Structural equation modeling (SEM) was performed in Mplus to analyze the hypothesized direct and mediation relationships. Multivariate analysis of variance (MANOVA) was performed to test the moderating hypotheses in SPSS (i.e., the interplay of brand trust and consumer brand identification in influencing internal and external attributions). Supporting the hypotheses, we found that brand trust positively influenced external attribution and external attributions, evoking brand forgiveness when individuals are exposed to communications related to CSR wrongdoings. However, contrary to our expectation, we found that the brand trust positively influenced internal attribution which indicated that higher the degree of faith individuals had in the brands, higher their tendency was to consider the possibility that the brand was indeed involved in unethical CSR practices.

Complete garment knitting technology is a method of producing knitted products, generally fashion garments, ready-made directly in the knitting machine without additional operations such as cutting and sewing. This makes it possible to manufacture a knitted fashion garment with fewer processes then with conventional production methods. In the fashion business customer demand is always changing due to fashion trends, so to be able to manufacture and deliver products rapidly is important. Mass customisation is a customer co-design process of products and services that tries to meets the needs of an individual customer’s demand for certain product features. In the fashion business this means that the customer can order a garment with a customised style, colour, size, and other personal preferences. The principal objective of this dissertation was to examine if and how complete garment technology can be applied to the customisation of knitted fashion products. It was pursued through several independent studies in knitting technology, mass customisation, and fashion logistics against a theoretical frame of reference in these areas. The papers in this thesis present various examples of how knitted fashion garments can be customised and integrated into fashion retailing concepts. The starting point of the research was the Knit-on-Demand research project conducted at the Swedish School of Textiles in collaboration with a knitting manufacturing and retailing company. The aim was to develop a shop concept built on the complete garment technology where a garment could be customised, produced, and delivered as quickly as possible. This initial idea failed due to the expense of investing in complete garment knitting technology, and so other avenues of research had to be found. The Knit-on-Demand project continued, using a business model similar to the complete garment concept but with the retail store and the production unit situated in different locations. The overall research question addressed in this thesis is: How can complete garment knitting technology be applied in a retail concept for customised garments? This question is then divided in two problems: What are the fashion logistics effects of combining complete garment technology and mass customisation? How does the co-design process function in the customisation of knitted fashion garments?The following is a qualitative study based on five research articles applying different research methodologies: case studies, simulations, and interviews. The empirical context is the area of mass customisation of fashion products and knitting technology, more specifically called complete garment knitting production technology. No prior studies describing mass customisation of complete garment knitting technology in combination with fashion logistics were found in the literature. The main contribution of this study is the demonstration that complete garment knitting technology can be applied in the customisation of fashion products. It also illustrates the importance of the co-design process between the company and the customer through which a knitted garment can be customised, produced, and delivered to the customer in three to five hours. The process of co-design and manufacture of a customised complete fashion product is examined, and the advantages and disadvantages associated with customisation of knitted garments are identified and described.

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Aufgrund der Klimakrise und der Notwendigkeit CO2-Emissionen zu reduzieren, ist in Zukunft mit einer steigenden Nachfrage an Leichtbaumaterialien wie textilverstärkten Verbundwerkstoffen zu rechnen. Aufgrund steigender Rohstoff- und Energiekosten verspricht der Einsatz von endkonturnahen Verbundwerkstoffen eine Reduktion der Herstellungskosten und des Abfalls. Herkömmliche Textiltechnologien sind nur begrenzt in der Lage die erforderlichen komplex geformten Textilien herzustellen. Um dieses Problem durch den Einsatz alternativer, noch nicht industriell etablierter Technologien zu lösen, beschäftigt sich diese Arbeit ausführlich mit der Entwicklung einer Häkelmaschine sowie der Untersuchung entsprechender Textilien. Häkeln ist eine maschenbildende Technologie, bei der im Gegensatz zum Stricken die Schlaufen, die eine Masche bilden, sowohl vertikal als auch horizontal aus zuvor gebildeten Maschen entspringen. Mit dem vielseitigen Häkeln ist es insbesondere möglich, komplexe dreidimensionale (3D) Formen zu erzeugen, da an jeder beliebigen Stelle eines Textils neue Maschen gebildet werden können. Bisherige Häkelmaschinenansätze sind unzureichend und bezüglich ihrer Skalierbarkeit zu einer industriell einsetzbaren Maschine stark eingeschränkt. Industriell etablierte Maschinen, die Häkelmaschinen genannt werden, sind in ihrer Bezeichnung irreführend, da es sich um Wirkmaschinen handelt, die nur grob die Häkelstruktur nachahmen, aber keine echten Häkelmaschen bilden können. Die hier entwickelte und patentierte Häkelmaschine namens Crochet Automaton (CroMat) ermöglicht erstmals die automatisierte Herstellung von Luftmaschen, Kettmaschen, festen Maschen, halben Stäbchen, Übergängen der Maschenreihen, Zunahmen sowie Abnahmen und auch anderen Operationen nach dem Prinzip des Flachhäkelns auf Basis einer Luftmaschenreihe. Darüber hinaus können neue Maschen durch ein manuelles Umhängen des produzierten Textils an nahezu beliebigen Stellen gebildet werden. Damit können komplex geformte 3D-Textilien entsprechend den Vorteilen des Häkelns hergestellt werden. Mit dem entwickelten CroMat-Prototyp lassen sich Formen herstellen, die für endkonturnahe Faserverbundwerkstoffe wie bspw. Doppel-T-Träger potenziell geeignet sind. Durch ein Aufhängen verschiedener Maschenreihen oder Textilien auf denselben Nadeln der Maschine ist es ebenfalls möglich diese mit dem Häkeln einer verbindenden Reihe zu fügen. Neben dem mechatronischen Prototyp mit zehn Achsen wird das weltweit erste Software-Tool für den Entwurf von maschinell gehäkelten Textilien entwickelt. Es beinhaltet eine Fehlerüberprüfung, die automatische Generierung des G-Codes für die Maschinensteuerung und eine Vorschau der entworfenen Textilien. Neben einer grafischen Benutzeroberfläche mit standardisierten Häkelsymbolen wird auch die Möglichkeit zur automatischen Generierung der Häkelstruktur entsprechend der Form eines zweidimensionalen (2D) Polygons geboten. Für die Vorschau wurde das erste Topologie-basierte Modellierungs-Framework für maschinell herstellbare Häkelstrukturen entwickelt. Eine ähnliche Modellierung wurde für manuell gehäkelte Stoffe entwickelt, die sich von den maschinell hergestellten nur darin unterscheiden, dass der Stoff nach jeder Reihe gewendet wird und somit die Maschen von verschiedenen Seiten aus gebildet werden. Beide Modellarten können als Grundlage für simulative Untersuchungen mit der Finite-Elemente-Methode (FEM) verwendet werden, die in dieser Arbeit zum ersten Mal zur Simulation von gehäkelten Textilien eingesetzt wurde. Darüber hinaus wurden erstmals die Zugeigenschaften von manuell gehäkelten Textilien systematisch untersucht und die Eigenschaften der ersten Faserverbundwerkstoffe mit gehäkelten Textilien erforscht. Gehäkelte Textilien (und entsprechende Verbundstoffe) haben grundsätzlich ähnliche Eigenschaften wie gestrickte Textilien, können aber tendenziell höheren Kräften standhalten. Zusammen mit den Formgebungsmöglichkeiten ist die CroMat-Häkelmaschine generell vielversprechend für die Automatisierung des Häkelns und insbesondere für die zukünftige Produktion von endkonturnahen Faserverbundwerkstoffen.:1 Introduction 1 1.1 Motivation 1 1.2 Aim 2 1.3 Work structure 3 2 Technical and scientific background 4 2.1 Crochet 4 2.1.1 Technique and stitch formation 5 2.1.2 Crocheting a fabric 8 2.1.3 Applications of crochet 11 2.1.4 Research overview on crochet 11 2.2 Knitting machines 15 2.2.1 Weft knitting 16 2.2.2 Warp knitting 19 2.2.3 Crochet gallon machines 21 2.3 Existing crochet machine approaches 23 2.3.1 First approach to automate crochet 23 2.3.2 Circular crochet machine approach 25 2.3.3 Crocheting with a robotic arm 27 2.3.4 Further attempts to automate crocheting 29 2.4 Rapid prototyping 30 2.4.1 Development approach 30 2.4.2 3D printing 31 2.5 Electric motors 33 2.5.1 Stepper 33 2.5.2 Servo motors 34 2.5.3 G-code 35 2.6 Textile composites 37 2.6.1 Composite production 37 2.6.2 Near net-shaped composites 38 3 Crochet machine development 39 3.1 CroMat innovation process 39 3.1.1 Development phases 39 3.1.2 Analyzing the first crochet machine approach 41 3.1.3 Definition of crochet machine prototype requirements 43 3.1.4 Crochet needle insertion process 47 3.1.5 Suspending stitches on auxiliary needles 55 3.1.6 Yarn guide and patent 57 3.2 Improvements beyond the patent 60 3.2.1 Analyzing the yarn feeding problem 60 3.2.2 Systematic identification of possible solutions 61 3.2.3 Implementation of the most suited solution 64 3.3 Automated crochet stitch formation 67 3.3.1 Initial situation 67 3.3.2 Slip stitch 68 3.3.3 Single crochet 71 3.3.4 Half double crochet 73 3.3.5 Turn 75 3.3.6 Chain stitch and skipping a stitch within a course 77 3.3.7 Increase stitches 79 3.3.8 Decrease stitches 82 3.3.9 Further methods for changing the fabric’s width 84 3.3.10 More complex stitches 87 3.4 Technical implementation of CroMat prototype 89 3.4.1 CroMat machine overview 89 3.4.2 Auxiliary needles 94 3.4.3 Crochet needle 100 3.4.4 Yarn guide 106 3.4.5 Stress on yarn and machine elements 109 3.4.6 Yarn tension 115 3.4.7 Firmware and motor control 117 3.5 Crocheting with the CroMat prototype 120 3.5.1 Producing an exemplary crocheted fabric 120 3.5.2 Movements for SC formation 122 3.6 Development of CroMat crochet design tool 125 3.6.1 Tool overview 125 3.6.2 User interface 126 3.6.3 Error checking 129 3.6.4 Preview of the fabric 130 3.6.5 Generating G-code 130 3.6.6 Discussing the design tool 132 3.7 CroMat requirement fulfillment 134 4 Research on crocheted fabrics 137 4.1 Modeling and simulation of manually crocheted fabrics 137 4.1.1 Modeling approaches for textiles 137 4.1.2 Developed modeling of crochet structures 138 4.1.3 FEM investigations 143 4.2 Mechanical characteristics of manually crocheted fabrics 146 4.2.1 Study overview 146 4.2.2 Materials and Methods 146 4.2.3 Influence of the crocheter 148 4.2.4 Influence of the crochet structure 150 4.2.5 Crochet composite 152 4.2.6 Evaluation of the results 155 4.3 Modeling and simulation of machine-crocheted fabrics 157 4.3.1 Modeling machine-crocheted fabrics 157 4.3.2 Modeling of INC and DEC 159 4.3.3 Simulative comparison of hand- and machine-crocheted fabrics 161 4.4 Generating machine producible crochet patterns in shapes of 2D polygons 164 4.4.1 Background 164 4.4.2 Developed polygon subdivision algorithm 165 4.4.3 Improving the subdivision’s quality 168 4.4.4 Crochet subdivision results for exemplary polygons 170 4.4.5 Discussing the results 176 4.5 Exemplary machine-crocheted fabrics 178 4.5.1 Basic fabric structure 178 4.5.2 Advanced possible structures 181 4.5.3 Poisson’s ratio investigation 185 5 Conclusion 189 5.1 Summary 189 5.2 Outlook 191 6 References 193 6.1 References of the author 193 6.2 Further references 193 / In the future, due to the climate crisis and the need to reduce CO2 emissions, an increasing demand for lightweight materials such as textile reinforced composites can be expected. Because of rising raw material and energy costs, the application of more near net-shaped composites is promising for reducing manufacturing costs and waste. However, conventional textile technologies are limited in their ability to produce the necessary complex-shaped textiles. In order to address this problem by using alternative technologies that have not yet been industrially established, this thesis deals extensively with the development of a crochet machine and the investigation of respective textiles. Crochet is a stitch-forming technology in which, unlike knitting, the loops of a stitch originate both vertically and horizontally from previously formed stitches. With versatile crochet, it is especially possible to create complex three-dimensional (3D) shapes because new stitches can be formed at any point on a fabric. Previous crochet machine approaches are inadequate and severely limited in scalability to an industrially applicable machine. Industrially established machinery called crochet machines are misleading in their designation because they are knitting machines that can only roughly mimic crochet structure but cannot form true crocheted fabrics. The Crochet Automaton (CroMat) crochet machine developed and patented here enables for the first time the automated production of chain stitches (CHs), slip stitches (SLs), single crochet stitches (SCs), half double crochet stitches (HDCs), turns (T1 and T2), increase stitches (INCs) as well as decrease stitches (DECs) and other operations according to the principle of flat crocheting based on a chain line. In addition, by manually removing and re-hanging the produced fabric, new stitches can be formed at almost any point to produce complex-shaped 3D textiles according to the capabilities of crochet. For example, it is possible to produce shapes relevant for near net-shaped composites such as double T-beams with the developed CroMat prototype. With manually suspending different stitch rows or fabrics on the machine, it is also possible to join them by simultaneously crocheting a course through them. In addition to the mechatronic prototype with ten axes, the world's first tool for designing machine-crocheted textiles is developed. It includes error checking, generation of the G-code for machine control and a preview of the designed fabrics. Beyond a graphical user interface (GUI) with standardized crochet symbols, a higher-level programmability is added through specifying a shape by 2D polygons and automatically generating corresponding, machine-crochetable patterns. The first topology-based modeling framework for machine-producible crochet structures was developed for the preview. A similar modeling was developed for manually crocheted fabrics, which differ from the machine-produced ones only in the fact that the fabric is turned after each row and thus the stitches are formed from different sides. Both models can be used as a basis for simulative finite element method (FEM) investigations, which were used in this work to simulate crocheted fabrics for the first time. Furthermore, the tensile properties of manually crocheted fabrics were systematically investigated for the first time and the properties of the first crochet composites were researched. Crocheted textiles (and corresponding composites) have basically similar properties as knitted textiles but have a tendency to withstand higher forces. Together with the shaping capabilities, the CroMat crochet machine is generally highly promising for the automation of crochet and especially for the future production of near net-shaped composite reinforcements.:1 Introduction 1 1.1 Motivation 1 1.2 Aim 2 1.3 Work structure 3 2 Technical and scientific background 4 2.1 Crochet 4 2.1.1 Technique and stitch formation 5 2.1.2 Crocheting a fabric 8 2.1.3 Applications of crochet 11 2.1.4 Research overview on crochet 11 2.2 Knitting machines 15 2.2.1 Weft knitting 16 2.2.2 Warp knitting 19 2.2.3 Crochet gallon machines 21 2.3 Existing crochet machine approaches 23 2.3.1 First approach to automate crochet 23 2.3.2 Circular crochet machine approach 25 2.3.3 Crocheting with a robotic arm 27 2.3.4 Further attempts to automate crocheting 29 2.4 Rapid prototyping 30 2.4.1 Development approach 30 2.4.2 3D printing 31 2.5 Electric motors 33 2.5.1 Stepper 33 2.5.2 Servo motors 34 2.5.3 G-code 35 2.6 Textile composites 37 2.6.1 Composite production 37 2.6.2 Near net-shaped composites 38 3 Crochet machine development 39 3.1 CroMat innovation process 39 3.1.1 Development phases 39 3.1.2 Analyzing the first crochet machine approach 41 3.1.3 Definition of crochet machine prototype requirements 43 3.1.4 Crochet needle insertion process 47 3.1.5 Suspending stitches on auxiliary needles 55 3.1.6 Yarn guide and patent 57 3.2 Improvements beyond the patent 60 3.2.1 Analyzing the yarn feeding problem 60 3.2.2 Systematic identification of possible solutions 61 3.2.3 Implementation of the most suited solution 64 3.3 Automated crochet stitch formation 67 3.3.1 Initial situation 67 3.3.2 Slip stitch 68 3.3.3 Single crochet 71 3.3.4 Half double crochet 73 3.3.5 Turn 75 3.3.6 Chain stitch and skipping a stitch within a course 77 3.3.7 Increase stitches 79 3.3.8 Decrease stitches 82 3.3.9 Further methods for changing the fabric’s width 84 3.3.10 More complex stitches 87 3.4 Technical implementation of CroMat prototype 89 3.4.1 CroMat machine overview 89 3.4.2 Auxiliary needles 94 3.4.3 Crochet needle 100 3.4.4 Yarn guide 106 3.4.5 Stress on yarn and machine elements 109 3.4.6 Yarn tension 115 3.4.7 Firmware and motor control 117 3.5 Crocheting with the CroMat prototype 120 3.5.1 Producing an exemplary crocheted fabric 120 3.5.2 Movements for SC formation 122 3.6 Development of CroMat crochet design tool 125 3.6.1 Tool overview 125 3.6.2 User interface 126 3.6.3 Error checking 129 3.6.4 Preview of the fabric 130 3.6.5 Generating G-code 130 3.6.6 Discussing the design tool 132 3.7 CroMat requirement fulfillment 134 4 Research on crocheted fabrics 137 4.1 Modeling and simulation of manually crocheted fabrics 137 4.1.1 Modeling approaches for textiles 137 4.1.2 Developed modeling of crochet structures 138 4.1.3 FEM investigations 143 4.2 Mechanical characteristics of manually crocheted fabrics 146 4.2.1 Study overview 146 4.2.2 Materials and Methods 146 4.2.3 Influence of the crocheter 148 4.2.4 Influence of the crochet structure 150 4.2.5 Crochet composite 152 4.2.6 Evaluation of the results 155 4.3 Modeling and simulation of machine-crocheted fabrics 157 4.3.1 Modeling machine-crocheted fabrics 157 4.3.2 Modeling of INC and DEC 159 4.3.3 Simulative comparison of hand- and machine-crocheted fabrics 161 4.4 Generating machine producible crochet patterns in shapes of 2D polygons 164 4.4.1 Background 164 4.4.2 Developed polygon subdivision algorithm 165 4.4.3 Improving the subdivision’s quality 168 4.4.4 Crochet subdivision results for exemplary polygons 170 4.4.5 Discussing the results 176 4.5 Exemplary machine-crocheted fabrics 178 4.5.1 Basic fabric structure 178 4.5.2 Advanced possible structures 181 4.5.3 Poisson’s ratio investigation 185 5 Conclusion 189 5.1 Summary 189 5.2 Outlook 191 6 References 193 6.1 References of the author 193 6.2 Further references 193