Amorphous Mg-Cu-Y metallic glasses are established by density functional theory and simulated annealing method in this study. The mechanical properties of amorphous Mg-Cu-Y metallic glasses are investigated by molecular statics simulations for the nano-indentation and the nano-scratch process. In this study, some potential energy parameters are obtained by fitting for describing the Mg-Cu-Y system. The bulk modulus, the Young¡¦s modulus and X-ray structure of the Mg-Cu-Y system are calculated. Our results are within 10% error compared with experimental values, which prove the correctness of fitted potential parameters. For the cases of nanoindentations, the indentation force-displacement and the influenced depth are calculated. The mechanical properties are obtained are close to experimental results. The both ¡§slip vector¡¨ and Honeycutt-Andemen index (HA index) parameters are also used to study the deformation behavior and bond-type of a group of atoms. Our results indicate that the influenced depths can be affected by the tip indentation and the gather of copper atoms. The gather of copper atoms can provide the resistance and strengthen the mechanical properties of Mg-Cu-Y material. On the other hand, our results indicate that the amorphous structure of Mg-Cu-Y metallic glasses cannot be transferred to crystal structure during nano-indentation process by analysis of HA index. For the cases of nano-scratch, two different scratch depth (5Å and 15Å) are investigated to understand the understand the depth effect. the scratch force-displacement curve is also obtained. As the same with nano-indentation results, the scratch force will increase because the gather of copper atoms and provide the resistance.

As part of a larger effort to understand the fundamental knowledge of polymer scratch behavior, this dissertation is focused on both experimental study and numerical analysis of scratch deformation of a broad range of polymers, with an emphasis on the mechanical understanding of how the scratch-induced damage is formed. An instrumented progressive load scratch method recommended by ASTM/ISO standards was adopted for the experimental work. The commercial finite element (FE) method package ABAQUS was employed as a numerical simulation tool to describe the stress-strain fields, and it analyzes the deformation mechanisms during the scratch process. A thorough parametric study has been performed to assess the influence of material parameters and surface properties, such as Young's modulus, yield strength, and friction coefficient, on the polymer scratch behavior. Upon investigation of the scratch behaviors of a broad range of polymer materials, various kinds of scratch damage features are identified and correlated with the mechanical characteristics of the polymers. A generalized scratch damage mechanism map for polymers is presented. Correlation between different material types and scratch damage mechanisms is made. It is found that both the material characteristics and the stress state exerted on the scratched surface are responsible for the observed scratch damage mechanisms. The phenomenological deduction of the scratch damage process based on the stick-slip mechanism is established. A more realistic material law for the scratch analysis is also provided. To evaluate the polymer resistance against scratch visibility quantitatively, an entirely new automated on-set scratch visibility determination methodology is developed based on typical visual characteristics of human eyes. Its application on the evaluation of mar and abrasion of polymer is also explored. This new methodology can quantify polymer scratch resistance consistently and reliably regardless of the sample surface characteristics and color.

This thesis presents the design of a scratch drive actuator (SDA) for Micro Motor Application. In accordance with the force needed to drive the mechanism, the relationship among SDA output force, geometries, and applied voltage is first constructed by employing the principle of virtual work. Having selected the topology of the device, the equations governing the motions and the forces of the micro motor and the actuator can be derived. The SDA and the associated micro motor mechanism are designed by considering the characteristics of Multi-User MEMS Processes, or MUMPs fabrication process. There are several types of SDA used for step motor application being designed and fabricated as illustrative samples. The chip well defined in MUMPs is released by immersing the chip in a bath of HF. It is followed by cleaning in DI water and IPA on a hot plate at 150¢J to reduce stiction.¡@The samples are inspected by OM and SEM, respectively.¡@The experimental and analytical results indicate the practicability of the proposed design concept.

The mechanical properties of the amorphous bulk metallic glassy (BMG) alloy, Mg58Cu31Y11, are examined by a non-traditional analytic method - nanoindentation scratch test. This thesis will discuss the influences of friction force, and fracture surface geometry on the BMG surface for load, depth of scratch, scratch velocity, and test temperature of the nano-scratch process. In this study, experimental factors, including load, depth of scratch, scratch velocity, and test temperature, are taken into consideration to investigate the effects of the friction force. And then, this research utilizes regression analysis to establish BMG machining experience formula. The significant parameters of the friction force on nano-scratch and the reliability of the prediction model are investigated by statistical software. According to the results, the friction force is nearly proportional to power of the load. The friction force exhibits a slightly dependence on the test temperature. Besides, the nano-scratch results show that the friction coefficient also increases as the load and test temperature increases. The results associated with the analysis of the variance can be practiced to assess the prominence among experimental factors. The analysis indicates that the load, test temperature play significant factors on the friction force. The results of the regression analysis using a statistical software can be applied to model the mathematical relationship between machining factors and friction force. It anticipates that the model is able to predict friction force over a wide variety of scratching conditions. The model is also proved in good agreement with experimental results.

Doctor of Philosophy / The drastic improvements in stiffness and strength even with the addition of small percentage of clay to a polymer are commonly traded-off with significant reductions in fracture toughness. It is believed that the presence of a stiff nano-filler will restrict the mobility of the surrounding matrix chains, and thus limit its ability to undergo plastic deformation, thereby decreasing their fracture toughness. To understand the role of rigid nano-fillers, like clay and their constraint effect on the surrounding polymer matrix, the effects of preferentially organized polyamide 6 lamellae in the vicinity of organoclay layers on the toughening processes are studied and compared with polyamide 6 filled with an elastomeric additive (POE-g-MA). It is suggested that to impart high toughness to polymer/organoclay nanocomposites, full debonding at the polymer-organoclay interface is necessary so that shear yielding of large volumes of matrix material can be enhanced. However, due to the strong tethering junctions between the individual organoclay layers and the matrix, full-scale debonding at the polymer-organoclay interface is rarely observed under stress conditions indicating that the constraint on the polymer adjacent to the clay is not relieved. Therefore, this has led to the development of ternary nanocomposites by adding a soft elastomeric dispersed phase to polymer/clay systems to obtain well-balanced mechanical properties. Polyamide 66/SEBS-g-MA/organoclay nanocomposites are prepared with four different blending protocols to understand the effect of blending protocol on the microstructure, mechanical properties and fracture mechanisms of the ternary nanocomposites so as to obtain new insights for producing better toughened polymer nanocomposites. In general, it is found that the level of enhancement of fracture toughness of ternary nanocomposites depends on: (i) the location and extent of dispersion of organoclay and (ii) the internal cavitation of rubber particles leading to effective relief of crack-tip tri-axial constraint and thus activating the matrix plastic deformation. Based on the wear/scratch damage studies on different polymer nanocomposite systems, it is suggested that elastic modulus and toughness of polymer nanocomposites are not the predominant factors controlling the material removal or friction coefficient and cannot be the sole indicators to compare and rank candidate materials. It is also found that nano-fillers by themselves, even if uniformly dispersed with good interfacial interaction with the matrix, do not irrevocably improve the wear (and friction) properties. Although it is important to consider these factors, it is necessary to thoroughly understand all microstructural parameters and their response to wear/scratch damage. Other important factors that should be considered are the formation of a uniform and stable transfer film on the counterface slider and the role of excessive organic surfactants or other modifiers added to disperse nanoparticles in a polymer matrix. It is also emphasized that the mechanisms of removal of materials during the wearing/scratching process should be studied meticulously with the use of high resolution microscopic and other analytical tools as this knowledge is critical to understand the surface integrity of polymer nanocomposites.

Η γλώσσα προγραμματισμού Scratch είναι ιδανική για την εισαγωγή στον προγραμματισμό. Η νέα αυτή γλώσσα ανήκει στο παράδειγμα του ταυτόχρονου προγραμματισμού. Στην εργασία αυτή περιγράφεται η σχεδίαση και η αξιολόγηση ενός εξαμηνιαίου μαθήματος για την εκμάθηση της Scratch με σκοπό αφενός να μελετηθεί ο τρόπος με τον οποίο οι αρχάριοι προγραμματιστές προσεγγίζουν το θέμα του συγχρονισμού και αφετέρου να διατυπωθούν προτάσεις για τη βελτίωση του μαθήματος. Η μεθοδολογία που εφαρμόστηκε είναι βασισμένη σε σχεδιασμό ερευνητική μεθοδολογία. / Scratch programming language is ideal for introductory programming courses. This new language follows the concurrent programming paradigm. Ιn the thesis the design and evaluation of a course for learning programming with Scratch is described. The approach that beginners programmers use for the necessary synchronization is studied and a new proposal for the laboratory course is presented. The design based research methodology is followed.

It is impossible to determine the amount of money that is spent every replacing products damaged from wear, but it is safe to assume that it is in the millions of dollars. With metallic materials, liquid lubricants are often used to prevent wear from materials rubbing against one another. However, with polymeric materials, liquid lubricants cause swelling, creating an increase in friction and therefore increasing the wear. Therefore, a different method or methods to mitigate wear in polymers should be developed. For better understanding of the phenomenon of wear, scratch resistance testing can be used. For this project, classic molecular dynamics is used to study the mechanics of nanometer scale scratching on amorphous polymeric materials. As a first approach, a model was created for polyethylene, considering intramolecular and intermolecular interactions as well as mass and volume of the CH2 monomers in a polymer chain. The obtained results include analysis of penetration depth and recovery percentage related to indenter force and size.

The purpose of this thesis work was to carry out initial studies on Scania’s possibility to have plastic rearview mirror glasses as that for example may reduce costs and problems for Scania’s customers and enable another design of the mirror assembly. It was performed by studying the legislative and Scania demands regarding rearview mirrors to write a test program, find and order plastic mirrors, and then perform the tests and evaluate the mirrors to see if they seem good enough for Scania’s trucks. A Scania technical regulation for rearview mirror glass was also written.   The tested mirrors were a Scania glass mirror as reference, a PC mirror from Sabic, a PC and a PMMA mirror from Specchidea, a mirror from SMR automotive, an ABS mirror from Ficocipa/Renault, an ABS mirror from Ford and a PC plastic from Bayer and they were tested for scratch resistance, temperature variations, impact resistance, corrosion and chemical resistance in that order. If a sample did not pass a certain test, it was not subjected to the next one.   Of all samples it was only the SMR mirror and the reference glass mirror that passed the first test (scratch resistance). The others became too scratched and were not tested further. The SMR and the glass mirror also withstood all the following tests very good, the SMR mirror was the best one of the tested mirrors. Probably the SMR mirror was the best one because many of the other mirrors did not seem to have been made for outdoor conditions and because it seemed to be the most modern mirror with a good abrasion resistant coating.   It was concluded that there is a future for plastic mirror glasses, that it would be interesting to do more tests on the mirrors, for example a UV test and a distortion test, and to test more mirrors as a new generation of plastic mirror glass seem to be underway. It would also be interesting to know how much cheaper and lighter the whole mirror assembly can become by changing to plastic mirror glass, which weighs 68% less than a glass mirror.

Programmering blev en del av den svenska grundskolans läroplan 2019 genom att skrivas in i matematikämnets kursplan. Därför är det viktigt att lärare vet hur de kan undervisa om detta. Dessutom kräver en stor andel av samhällets yrken en viss del av programmeringskunskap.  Syftet med studien är att i matematikdidaktisk forskning undersöka hur undervisning om programmering kan bedrivas i grundskolan. Syftet besvaras genom frågorna: vilka faktorer motiverar enligt forskning, att programmering behövs i matematikundervisningen, och hur kan matematikundervisningen utformas så eleverna får möjlighet att utveckla kunskap om programmering? Litteraturen för studien samlades in genom sökningar i databaser. Materialet som undersöktes är vetenskapliga artiklar, där såväl nationella som internationella studier har genomförts. Samtliga artiklar är skrivna på engelska.  Det insamlade materialet analyserades genom en översiktsmatris, dessutom användes innehållskriterier för att bedöma artiklarnas relevans för studien. Resultatet visade att programmering kan vara en möjlighet inom matematikundervisningen och även ha en positiv påverkan i andra delar av matematiken enligt genomförda studier och undersökningar. Resultatet visar även att undervisning i programmering kan genomföras både med och utan digitala verktyg. Området är relativt nytt i matematikundervisningen och kräver vidare undersökning. En del lärare uttrycker en osäkerhet kring hur deras undervisning ska bedrivas.

Two families of PVD hard coatings were successfully used for high performance end milling of hardened H13 tool steel. The first family of coatings are AlCrN-based, they are used for wet machining and the other family is based on TiAlCrSiYN coating and are used for dry machining of H13. It was shown that there is a strong potential for further advancement in the wear performance of the coatings by improving the coating architecture as well as by varying the deposition parameters used during their synthesis. A number of deposition parameters of the coatings show a strong impact on wear performance of the cutting tools. Wear performance was related to the structure and a number of nano-mechanical characteristics of the coating layer assessed using the NanoTest system produced by Micro Materials. It was shown that critical characteristics like nano-hardness, loading support factor and nano-scaled scratch resistance can be used to predict the wear performance of a cutting tool. / Thesis / Master of Applied Science (MASc)