This thesis develops an algorithm to decrease high-curvature sections in tool paths for complex parts to achieve shorter machining times resulting in higher production rates. In the research sample cases, the algorithm decreased machining times by 1% to 9% for design-induced sections of high curvature and by 16% to 75% for CAM induced ripples using high path tolerances. High-curvature sections in tool paths are caused by complex part geometry, noise, and discontinuities in the model. The curvature is decreased by deviating the tool path within an allowable path tolerance. The feedrate along the tool path is directly related to the curvature of the tool path. High-curvature sections cause the NC machine to reduce the feedrate along the tool path due to acceleration and jerk limits. These lower feedrates increase machining time and slow production rates. This new algorithm decreases curvature, which increases feedrates and decreases machining times, thereby increasing production rates for manufacturing companies. The tool paths are represented by cubic B-splines. The algorithm is based on the basic principle that the curvature of a B-spline directly relates to the geometry of its control polygon. If the control polygon's geometry has many tight corners then the B-spline will have high curvature. If the control polygon's geometry is a straight line then the B-spline will be a straight line with zero curvature. The algorithm deviates the control polygon's points so that they move towards forming a straight line. The control polygon will rarely form a straight line because the spline is limited by the path tolerance. However, as the control polygon moves towards forming a straight line, the curvature decreases, which allows the feedrate to increase. Six sample cases are explored in which the machining time is decreased. Three of the cases are tool paths that contain curvature sections with a range of unnecessary curvature from low to high. One sample is the tool path for the complex geometry in a snow tire mold. Another sample tool path contains ripples caused by noise in the CAD model. The last tool path contains ripples caused by tangency discontinuities in the CAD model. The percent of time saved directly relates to the severity of the curvature in the part. This thesis provides a quick and efficient means to reduce curvature in complex parts, resulting in decreased machining times and increased production rates.

Detta arbete är en uppgift som är mottagen från SNA Europe och genomförd under vårterminen 2018. SNA Europe är en europeisk tillverkare av framförallt handverktyg med huvudsaklig produktion i Europa med en internationell marknad. Syftet med arbetet är att förse SNA Europe med underlag i form av fakta, analyser och slutligen ett förslag på ett produktkoncept. Förslaget på produktkonceptet gäller en sk snabbvinkel, ett markerings- och mätverktyg baserat på Swansons Tools original Speed Square. Snabbvinkeln är mycket populär i USA men används inte i Europa, därför av intresse för SNA Europe. Arbetet planerades upp i fyra faser över en tio veckors period där faserna strukturerades upp i ingående underfaser. Det initiala arbetet har gått ut på att leta fakta om och analysera uppgiften för att kunna bygga en grund för en konceptframtagning. Då tillräcklig information erhållits påbörjades design- och utvecklingsarbetet av ett produktkoncept med en fastställd konceptdefinition. Slutligen efter CAD-modellering och prototypframtagning resulterade arbetet i en så gott som fullt färdigt produktkoncept som SNA Europe kan tillverka i egen fabrik. Framarbetat produktkoncept förverkligades i form av en slutgiltig prototyp tillverkad av SNA Europe. / This work is a task received from SNA Europe and completed during the spring term of 2018. SNA Europe is a European manufacturer of mainly hand tools with main production in Europe with an international market. The purpose of the work is to provide SNA Europe with a basis in the form of facts, analyses and finally a proposal for a product concept. The proposal for the product concept concerns a so-called rafter square, a marking and measurement tool based on Swansons Tools original Speed Square. The rafter square is very popular in the United States but is not used in Europe, therefore of interest to SNA Europe to make a own design. The work was planned in four phases over a ten week period, where the phases were structured into in-depth phases. The initial work has been to search for facts and analyse the task in order to build a foundation for a conceptualization. When sufficient information was obtained, the design and development work began with a product concept with a defined concept definition. Finally, after CAD modelling and prototype production, the work resulted in an almost complete product concept that SNA Europe can manufacture in its own factory. Developed product concepts were implemented in the form of a final prototype manufactured by SNA Europe.

This paper explores what attributes are important for the creation of environment art tools. The purpose of this is to make sure that when a tool is to be developed, it will be done properly within a given time frame. This is important since the cost of tool development is high in both time and capital spent. Being able to make sure that when those resources are spent, that the resulting tool is of high quality and solving the problem which the development team set out to do. Through interviews, forms and the creation of our own tool I hope to find these attributes and to be able to provide insights into how a studio or team might apply them for their own purposes.

Vombsjön är en av de viktigaste dricksvattentäkterna i södra Skåne som förser bland annat Malmö och delar av Lund med dricksvatten. Sjön lider av övergödning och återkommande algblomningar som komplicerar dricksvattenproduktionen. Fosfor från sjöns bottensediment (intern belastning) och fosfor från det jordbruksdominerade avrinningsområdet (extern belastning) behöver kartläggas för att råda bukt på övergödningsproblematiken i sjön och trygga produktionen av ett säkert dricksvatten. Inom ramen för detta examensarbete har den externa fosforbelastningen kartlagts genom modellering av Vombsjöns avrinningsområde med den hydrologiska modellen Soil and Water Assessment Tool (SWAT+). Resultaten från modelleringen visar att det nära 45 000 ha stora avrinningsområdet i genomsnitt tillför 25 ton totalfosfor per år via de tre huvudvattendragen som mynnar ut i Vombsjön. Medelvärdet är beräknat på simuleringar gjorda för åren 2011 – 2022 och belastningen varierar mellan 14–37 ton totalfosfor för de undersökta åren. 79 % av totalfosforn tillförs sjön via det största vattendraget Björkaån, 11 % via Torpsbäcken och 10 % via Borstbäcken. Den månatliga vattenföringen har manuellt kalibrerats och validerats mot en mätpunkt i avrinningsområdet. Miljöövervakning från ett jordbruksdominerat typområde i samma läckageregion som Vombsjöns avrinningsområde till största del ligger inom användes för att jämföra storleksordningen på den arealspecifika fosfortransporten. De arealspecifika månads- och årstransporterna låg inom samma storleksordning men variationerna mellan de två områdena var stora somliga år och månader. Den hydrologiska modellen behöver vidareutvecklas för att bättre simulera vattenföringen under höst och vinter, när vattenföringen generellt är som störst. Vidare behöver modellen kalibreras och valideras mot fler vattenföringsstationer och uppmätta fosforhalter i avrinningsområdet för att avgöra hur väl modellen simulerar fosfortransporten. / Vombsjön is one of the most important drinking water sources in southern Skåne, supplying drinking water to Malmö and parts of Lund. The lake suffers from eutrophication and reoccurring algal blooms which are complicating the drinking water production. Phosphorus leaching from the bottom sediment of the lake (internal load) and phosphorus coming from the agriculture- dominated catchment (external load) needs to be investigated to address the eutrophication issues and ensure a safe drinking water production. As part of this thesis, the external phosphorus load has been investigated through hydrological modeling of the catchment area, using Soil and Water Assessment Tool (SWAT+). The modeling results show that the approximately 45 000 hektar big catchment area contributes to an average of 25 tons of total phosphorus per year via the three main watercourses that flows into Vombsjön. The average load is based on simulations between 2011 and 2022, and the load varies between 14–37 tons of total phosphorus for the examined years. 79 % of the total phosphorus load is supplied to the lake via the largest watercourse, Björkaån, 11 % via Torpsbäcken and 10 % via Borstbäcken. The monthly water flow has been manually calibrated and validated against flow measurements at one point in the catchment area. Environmental monitoring data from an agriculture- dominated catchment area, located in the same leakage region as most of the Vombsjöns catchment area, was used to compare the magnitude of the area-specific phosphorus transport. The area-specific monthly and annual transports of total phosphorus were within the same order of magnitude, but there were significant variations between some years and months. The hydrological model needs further development to better simulate water flow during autumn and winter, when the flow is generally highest. Furthermore, the model needs to be calibrated and validated against more flow stations and measured phosphorus concentrations within the catchment area to determine how well the model simulates phosphorus transport.

Syftet med den här studien är att undersöka hur rörlig bild kan öka konsumentens förtroende för en produkt vid e-handel, och för att se om det eventuella ökandet av förtroende för produkter kan få fler kunder att vilja handla online. Målet med studien är att se hur påverkad användaren blir av rörlig bild när den handlar kläder på en webbplats. Den utvalda metoden för studien var en observation med sju kvinnor i form av ett användartest där respondenterna fick visualisera ett köp av en specifik produkt på två olika webbplatser, med en efterföljande intervju med tio öppna frågor. Resultatet av studien visade att majoriteten av de tillfrågade föredrog att handla på en webbplats som använde rörlig bild vid presentation av produkten, eftersom det gav en mer realistisk bild av klänningen. Slutsatsen resulterade i att rörlig bild visualiserade produkten mer verklighetstroget till skillnad från en e-handelsplats som endast använde produktbilder. Den rörliga bilden var det närmaste konsumenten kunde komma till verkligenheten och det ökade i sin tur förtroendet för produkten och har resulterat i att fler konsumenter ville handla produkten. Den rörliga bilden fungerade därmed som ett substitut för den fysiska kontakten konsumenten annars skulle haft med produkten i realiteten. Slutsatsen kan därför dras om att rörlig bild ökar förtroendet för en specifik produkt vid e-handel. / The purpose of the study is to research how moving images can increase the confidence for the customer in a specific product in e-commerce. Furthermore, the study aimed to see if moving images could increase the number of people wanting to shop online. The reason behind the study is to see how customers who are interested in buying clothes respond to moving images. The chosen method for the study was to observe seven women participating in a usability test to envision purchasing a chosen product on two separate websites. Following the usability test, each woman was interviewed with ten open questions.The results of the study showed that the majority of the respondents preferred to shop on awebsite that used moving images to present a product, as it presented the product in a morerealistic image. Because the respondents could not see the dress in reality, a catwalk video was the most effective way to present the dress to the customer. The catwalk video thus increased the confidence of the customer in the product, in which subsequently lead to an increased number of consumers wanting to purchase the product. The moving images served as a substitute for the physical contact the consumer would otherwise have with the product in reality. It is therefore appropriate to conclude that moving images can increase the confidence in a customer for a certain product in e-commerce.

Machining chatter is an undesirable phenomenon of material removal processes and hardly to control or avoid. Its occurrence and extent essentially depend onthe kinematic, which alters with the position of the Tool Centre Point, of the machine tool. Research as to chatter was done widely but rarely with respect to changing structural dynamics during manufacturing. This thesis applies intelligent methods to learn the underlying functions of modal parameters – natural frequency, damping ratio, and mode shape – and defines the dynamic properties of a system firstly at this extent. To do so, it embraces three steps: first, the elaboration of the necessary dynamic parameters, second, the acquisition of the data via a simulation,and third, the prediction of the modal parameters with two kinds of Machine Learning techniques: Gradient Boosting Machine and Multilayer Perceptron. In total, it investigates three types of kinematics: cross bed, gantry, and overhead gantry. It becomes apparent that Light Gradient Boosting Machine outperforms Multilayer Perceptron throughout all studies. It achieves a prediction error of at most 1.7 % for natural frequency and damping ratio for all kinematics. However, it cannot really control the prediction of the participation factor yet which might originate in the complexity of the data and the data size. As expected, the error rises with noisy data and less amount of measurement points but at a tenable extent for both natural frequency and damping ratio. / 'Bearbetningsvibrationer är ett oönskat fenomen i materialborttagningsprocesser och är svåra att kontrollera eller undvika. Dess förekomst och omfattning beror i huvudsak på kinematiken, som förändras med positionen för verktygets centrumpunkt på verktygsmaskinen. Det har gjorts mycket forskning om bearbetningsvibrationer, men sällan om förändrad strukturell dynamik under tillverkningen. I denna avhandling tillämpas intelligenta metoder för att lära sig de underliggande funktionerna hos modalparametrar – egenfrekvens, dämpningsgrad och modalform – och definierar systemets dynamiska egenskaper för första gången i denna omfattning. För att göra detta omfattar den tre steg: för det första utarbetandet av de nödvändiga dynamiska parametrarna, för det andra insamling av data via en simulering och för det tredje förutsägelse av modalparametrarna med hjälp av två typer av tekniker för maskininlärning: Gradient Boosting Machine och Multilayer Perceptron. Sammanlagt undersöks tre typer av kinematik: crossbed, gantry och overhead gantry. Det framgår tydligt att Light Gradient Boosting Machine överträffar Multilayer Perceptron i alla studier. Den uppnår ett prediktionsfel på högst 1,7 % för egenfrekvens och dämpningsförhållande för alla kinematiker. Den kan dock ännu inte riktigt kontrollera förutsägelsen av deltagarfaktorn, vilket kan bero på datans komplexitet och datastorlek. Som väntat ökar felet med bullrig data och färre mätpunkter, men i en acceptabel omfattning för både naturfrekvens och dämpningsförhållande.

Machine tools accuracy has been a cornerstone in defining machining system capability and directly affecting dimensional and geometrical tolerance of machined parts. The effort for achieving higher precision and accuracy can be distinguished in two general ideas. One is to improve performance of machine tools by designing better, stiffer and more accurate machine tools. The other is to develop tools and methods for evaluating and measuring their behaviour and gain knowledge of their performance. In order to properly control the machine tool characteristics that can affect and improve their accuracy such as static stiffness and static accuracy.This thesis is aiming at establishing and further advancing the idea of loaded testing of machining systems and the concept of Elastically Linked Systems as a framework for measuring, identifying and characterising quasi-static stiffness of machine tools under loaded conditions. This will allow the creation of an improved capability profile of machining system accuracy. The focus is on the implementation of Elastically Linked Systems concept (ELS) through the Loaded Double Bar system, a measurement method that can partly simulate the process-machine interaction by reproducing forces exerted on the machine tool structure for the evaluation of system characteristics under loaded condition. This allows the qualitative and quantitative evaluation and comparison of machine tools for the purpose of accuracy enhancement, identification of weak directions with potential utilization in process planning, machine procurement and maintenance.Through two case studies, the capability to identify the effect of machine components and structure behaviour is shown. / <p>QC 20180514</p>

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

Master of Science / Department of Industrial & Manufacturing Systems Engineering / Malgorzata J. Rys / The current state of the dental industry shows an increasing number of dentists and dental hygienists who are reducing hours and retiring early due to the injuries sustained while working. These injuries, or cumulative trauma disorders, can be reduced by applying ergonomics in dental tool design. The goal of ergonomics is to reduce current injuries but also prevent future ones. In addition, population demographics have shown an increasing trend in female dentists. With a shift from the male dominated field, design for different anthropometric measurements needs to be investigated. In order to pinpoint sources of pain, a survey was designed and distributed to dentists in Kansas, Missouri, and Texas. Even with a small sample size (n=24), results confirmed past studies in the dental industry of pain originating in the neck, shoulder, lower back, and wrist/hand region. The reasons stemmed from the repetitive motions and forces applied during dental procedures. Responses also found that ergonomic principles need to be applied to the handle and grip portion of dental scaler design. Dental scaling is the procedure to remove deposits on teeth, such as plaque and calculus, most commonly performed by dental hygienists. First, the history of dental tools, angulation, tool weight, and materials currently utilized were researched before looking into specific design factors for modification. Currently, the handle grip area on all dental tools range in size, but a 10 mm grip has been proven to be optimal. The optimal tool weight has yet to be determined as 15 grams is the lowest weight to be tested. Most tools are made of stainless steel and resins, which are not compressible. An experiment was designed to test a new dental scaler (A) made of a titanium rod with added compressibility in the precision grip area. The aim was to help reduce pressure on the fingers and hand muscles and increase comfort during scaling. The experiment utilized a Hu-Friedy sickle scaler (B) and a Practicon Montana Jack scaler (C) as controls to show two design spectrums, weight and material. The subjects (n=23) were taught the basics of scaling and required to scale using a typodont. The change in grip strength (Δ GS), pinch strength (Δ PS), and steadiness of the subjects hand were tested. An absolute and relative rating technique was utilized pinpointing that the new dental scaler was preferred with the eigenvector (A=0.8615, B=0.1279, C=0.0106). Statistical analysis confirmed this tool preference while also finding the interaction of gender and tool and Δ GS Tool A versus Tool B for males to be significant.

The study investigated the feasibility of the Ottawa decision support tool to assist HIV positive mothers' infant feeding choice. The aim was to explore and describe the feasibility of the Ottawa Decision Support Tool (ODST) in counselling HIV infected pregnant women on decision-making regarding the choice of safe infant feeding. The finding of this study will assist and support HIV positive mothers to be independent decision makers in choosing an infant feeding option for their babies. A descriptive qualitative research approach guided the researcher to explore and describe the feasibility of the ODST to assist HIV positive mothers' infant feeding choice. This study is based on the Ottawa decision support framework (ODSF). Three focus group that comprised midwives as participants were conducted. The first focus group was conducted in January 2013 and the two subsequent ones in August 2013. Data was analysed using a framework approach. The following themes emerged from data-analysis: • Appropriateness • Receptiveness of intervention • Effectiveness Conclusions were drawn based on the attained objectives of the study. The overall conclusion was that the ODST is feasible to assist HIV positive mothers' infant feeding choice. Limitations of the study were identified and recommendations were made for nursing practice, nursing education and further research. / MCur, North-West University, Potchefstroom Campus, 2015