An experimental study of several variants of radius and strut angle of the body centered cubic unit cell was performed to determine the mechanical properties and failure mechanisms of the mesostructure. Quasi static compression tests were performed on an Instron® universal testing machine with a 50kN load cell at 0.2mm/min. The test samples were built using a SLM Solutions 125 selective laser melting machine with 316L stainless steel. Test specimens were based on 5mm cubic unit cells, with a strut diameter 10% of the unit cell size, with skins on top and bottom to provide a cantilever boundary constraint. Specimens were inspected for dimensional accuracy using precision calipers and inspected for morphology using a MicroVu® macroscope. The compressive properties of the mesostructure was compared to the compressive properties of macrostructure. The BCC unit cell behaves significantly different at the boundary layer of a constrained lattice. The failure mode at the boundary is characterized by plastic bending within the microstruts while the non boundary layer cells fail via plastic bending at the node. Manufacturing compensation parameters were determined for part shrinkage and droop. Two predictive numerical models were developed, based on the Gibson-Ashby model of cellular solids, as well as a finite element model. Numerical results did not agree well with the experimental results, indicating that the droop observed on the structures significantly affects the mechanical properties of the overall structure. The 25% radius cubic unit cell and 3^3 lattice withstood the greatest stress of all specimens tested and exhibited nearly ideal plastic deformation behavior.

No description available.

<p> Laser powder bed fusion (LPBF) is a rapidly emerging manufacturing technology capable of producing complex part geometries through the repeated, precise laser melting of metallic powder layers. At present, the process is primarily employed in high-value-added applications which exist in the aerospace, biomedical, and dental industries. As industrial implementation of LPBF has matured, research has focused on established materials for which there are already large bodies of literature and regulatory approval, such as Inconel 718, Inconel 625, Ti-6Al-4V, and 316 stainless steel. However, the rapid solidification process inherent to LPBF leads to vastly different microstructures with improved strength compared to these traditional materials in cast or wrought forms. In general, the high solidification velocity and thermal gradients result in cellular and dendritic solidification structures with finer grain and precipitate sizes than conventionally processed alloys. These microstructure changes warrant the exploration of new alloy systems and reevaluation of historically cast compositions with optimized microstructures, especially considering the tunability of a digitally controlled fabrication process. This work examines laser powder bed fusion of Mar-M 509, a carbide-strengthened cobalt alloy that is typically investment cast directly into complex-shaped components such as nozzle guide vanes (NGVs). NGVs are stationary components in gas turbine engines for propulsion and energy production which require strength under moderate mechanical loading at high temperatures. Investment cast microstructures have porosity defects in slower-cooled regions due to lack of liquid feed to interdendritic regions. As-printed, the cellular and dendritic Mar-M 509 LPBF microstructures lead to the formation of continuous, fiber-like, eutectic carbide structures in the intercellular and interdendritic regions, which limit macroscopic ductility. Thermo-Calc is used for calculation of phase diagrams (CALPHAD) to estimate the equilibrium transformation temperatures of MC, M23C6, and M7C3-type carbides, which informs design of isothermal heat treatments to engineer microstructures with enhanced ductility over the as-printed or cast versions of Mar-M 509 while maintaining tensile strength. Scanning and transmission electron microscopy reveals the composition and distribution of carbide phases as a function of heat treatment temperature. Lastly, heat treatment recommendations for nozzle guide vanes are made.  </p>

Fragmenterande stridsdelar har funnits länge och idag finns tre huvudsakliga metoder för att uppnå fragmentering i en stridsdel. Metoden styrd fragmentering som undersöks i arbetet fungerar generellt sett bra men saknar önskad kontrollförmåga. Målet med arbetet var att utveckla koncept av styrt fragmenterande stridsdelar och undersöka om fragmentspridningen kan riktas och snävas in till mindre än ±20° enligt två fall, cirkelskiva och cirkelsektor. De framtagna koncepten önskades vara tillverkningsbara med additiv tillverkning och lämpligheten för detta skulle därför undersökas. I samband med detta önskades även ett materialval. Examensarbetet genomfördes i samarbete med uppdragsgivaren Saab Dynamics AB och Karlstads universitet. Arbetet följde en teknikutvecklingsprocess innefattande en förstudie där vetenskaplig litteratur studerades och kontakt etablerades med tillverkare samt områdesexperter för att undersöka möjligheterna. Följande förstudien genomfördes en konceptutvecklingsprocess där de 3D-modellerade konceptens funktion undersöktes och verifierades med SPH-simuleringar i IMPETUS Afea. Ett materialval gjordes utifrån tillverkarens tillgängliga material samt önskvärda materialegenskaper och konceptens tillverkningsbarhet undersöktes. De slutsatser som kan dras utifrån teknikutvecklingen är att det med styrd fragmentering är möjligt att rikta en stridsdels fragment till önskade spridningsfall, dock med förbättringsmöjligheter med avseende på bland annat fragmentens massfördelning. Koncepten som framställdes visades vara lämpliga att tillverka med additiv tillverkning då de framtagna geometriernas komplexitet gynnas av de ökade frihetsgraderna samt då det valda materialet tillät en godtagbar fragmentering och var tillverkningsbart med AM. Prototyper tillverkades i plast men verkliga tester genomfördes ej. Verkliga tester och vidare optimering av tekniken lämnades som framtida arbete. / Fragmentation warheads have been used for a long time and today there are three main methods of achieving fragmentation in a warhead. The method studied in this work is controlled fragmentation, a method that generally works adequately but can only control the fragmentation to a certain degree. The goal of this project was to develop multiple concepts of controlled fragmentation warheads and investigate whether it is possible to aim and reduce the projection angle of the fragments to ±20° for two cases, circular disc and circle sector. It was wished for the developed concepts to be manufacturable with additive manufacturing, its feasibility to be studied and therefore a material selection with this in mind to be done. The thesis work has been carried out in collaboration with Saab Dynamics AB and Karlstad University. A technology development process was used consisting of a literature study where scientific literature was studied and contact was established with the manufacturer as well as other experts in the field of study in order to examine the possibilities regarding the project. Following the literature study, a concept development process was carried through where the function of the 3D-modeled concepts were examined and verified through SPH-simulations in IMPETUS Afea. A material selection was done with regards to the manufacturers available materials and the sought after material properties. Finally, the concepts manufacturability was examined and verified. The conclusions drawn from this technology development are the following: It is possible to both reduce the projection angle and aim the resulting fragments to the specified cases, although with great room for improvement regarding, among other things, the fragment mass distribution. The presented concepts proved to be suitable for additive manufacturing, because of their geometric complexity where the increased design freedom of AM is greatly benefited. The chosen material also proved suitable for both AM and use in fragmenting warheads. Plastic prototypes were made but real experimental tests were not conducted. Real experiments and further optimization of the technology were left as future work.

The selective laser melting (SLM) process allows for the control of unique part form and function characteristics not achievable with conventional manufacturing methods and has thus gained interest in several industries such as the aerospace and biomedical fields. The fabrication processing parameters selected to manufacture a given part influence the created material microstructure and the final mechanical performance of the part. Understanding the process-structure and structure-performance relationships is very important for the design and quality assurance of SLM parts. Image based analysis methods are commonly used to characterize material microstructures, but are very time consuming, traditionally requiring manual segmentation of imaged features. Two Python-based image analysis tools are developed here to automate the instance segmentation of manufacturing defects and subgranular cell features commonly found in SLM 316L stainless steel (SS) for quantitative analysis. A custom trained mask region-based convolution neural network (Mask R-CNN) model is used to segment cell features from scanning electron microscopy (SEM) images with an instance segmentation accuracy nearly identical to that of a human researcher, but about four orders of magnitude faster. The defect segmentation tool uses techniques from the OpenCV Python library to identify and segment defect instances from optical images. A melt pool structure generation tool is also developed to create custom melt-pool geometries based on a few user inputs with the ability to create functionally graded structures for use in a virtual testing framework. This tool allows for the study of complex melt-pool geometries and graded structures commonly seen in SLM parts and is applied to three finite element analyses to investigate the effects of different melt-pool geometries on part stress concentrations. / Master of Science / Recent advancements in additive manufacturing (AM) processes like the selective laser melting (SLM) process are revolutionizing the way many products are manufactured. The geometric form and material microstructure of SLM parts can be controlled by manufacturing settings, referred to as fabrication processing parameters, in ways not previously possible via conventional manufacturing techniques such as machining and casting. The improved geometric control of SLM parts has enabled more complex part geometries as well as significant manufacturing cost savings for some parts. With improved control over the material microstructure, the mechanical performance of SLM parts can be finely tailored and optimized for a particular application. Complex functionally graded materials (FGM) can also easily be created with the SLM process by varying the fabrication processing parameters spatially within the manufactured part to improve mechanical performance for a desired application. The added control offered by the SLM process has created a need for understanding how changes in the fabrication processing parameters affect the material structure, and in turn, how the produced structure affects the mechanical properties of the part. This study presents three different tools developed for the automated characterization of SLM 316L stainless steel (SS) material structures and the generation of realistic material structures for numerical simulation of mechanical performance. A defect content tool is presented to automatically identify and create binary segmentations of defects in SLM parts, consisting of small air pockets within the volume of the parts, from digital optical images. A machine learning based instance segmentation tool is also trained on a custom data set and used to measure the size of nanoscale cell features unique to 316L (SS) and some other metal alloys processed with SLM from scanning electron microscopy (SEM) images. Both these tools automate the laborious process of segmenting individual objects of interest from hundreds or thousands of images and are shown to have an accuracy very close to that of manually produced results from a human. The results are also used to analyze three different samples produced with different fabrication processing parameters which showed similar process-structure relationships with other studies. The SLM structure generation tool is developed to create melt pool structures similar to those seen in SLM parts from the successive melting and solidification of material from the laser scanning path. This structural feature is unique to AM processes such as SLM, and the example test cases investigated in this study shows that changes in the melt pool structure geometry have a measurable effect, slightly above 10% difference, on the stress and strain response of the material when a tensile load is applied. The melt pool structure generation tool can create complex geometries capable of varying spatially to create FGMs from a few user inputs, and when applied to existing simulation methods for SLM parts, offers improved estimates for the mechanical response of SLM parts.

Additive manufacturing (AM), or 3D-printing, allows for rapid prototyping and complex design and gives an insight into how customers may use recent technology to co-create value. Metal additive manufacturing reaching market maturity broadens the playing field for the ability to create personalized products. The idea of value co-creation places customers in the center. However, there is a lack of knowledge about how customers engage in collaborative processes where aesthetics and embodied experiences manifest with the development of new products. By empirically researching the phenomenon in the field of technology and understanding the roles of aesthetics, customer-centered approaches to innovation may become more fruitful. This research applies technology entrepreneurship studies with aesthetics, more specifically the embodied processes that occur during the value co-creation of complex technology. A 4-month micro-ethnography of an AM firm was conducted to explore the aesthetics of value co-creation. Expanding on the work of Elias et al. (2018) and Aarikka-Stenroos and Jaakkola (2012), value co-creation in a complex technology field was explored. The key insight in this thesis is that customers may come with valuable contributions during the commercialization of technology, not only when trying to make sense of the technology, but also insights into where the technology may be applied.

Выпускная квалификационная работа, 67 с., 9 рис., 9 табл., 25 источников. Объект исследования – способы плавки медных концентратов. Предмет исследования – поиск наиболее эффективного способа плавки медных концентратов. Цель работы – провести ряд технологических и экономических расчетов, на основании которых определить наиболее эффективный способ плавки медных концентратов. В процессе работы были проведены расчеты материальных балансов и тепловых балансов для выбранных способов плавки медных концентратов. Также проведен сравнительный анализ выбранных способов плавки по полученным результатам расчетов и проведена предварительная экономическая оценка инвестиционного проекта, предполагающего замену отражательных печей предприятия ОАО «Святогор» на печи, являющимися основным оборудованием для того способа плавки, который будет выбран наилучшим по результатам анализа. В результате работы был сделан вывод об эффективности выбранных способов плавки медных концентратов относительно друг друга, среди которых был выбран наиболее эффективный способ плавки. А также проведена предварительная экономическая оценка инвестиционного проекта, предполагающего замену отражательных печей предприятия ОАО «Святогор» на печи, являющимися основным оборудованием для того способа плавки, который будет выбран наилучшим по результатам анализа. / Final qualifying work, 67 pp., 9 pics., 9 tables, 25 references Object – methods of melting copper concentrates. Subject – search for the most effective method of melting copper concentrates. The purpose of the work is to carry out a number of technological and economic calculations on the basis of which the most effective method of melting copper concentrates is determined. In the course of work, material balances and heat balances were calculated for the selected methods for melting copper concentrates. The analysis of the selected melting methods was also carried out based on the results of calculations, and a preliminary economic evaluation of the investment project was carried out, involving the replacement of the reflector furnaces of the Svyatogor enterprise with the furnace, which is the main equipment for the melting method to be chosen as best according to the analysis. As a result of the work, a conclusion was made about the effectiveness of the chosen methods of melting copper concentrates relative to each other, among which the most effective method of melting was chosen. Also, a preliminary economic evaluation of the investment project was carried out, which involves replacing the reflective furnaces of the Svyatogor enterprise with the furnace, which is the main equipment for the melting process, which will be chosen the best according to the results of the analysis.

The archaeological site Pigloner Kopf (Vadena/Pfatten, South Tyrol, Italy) has revealed unexpected elements related to the local Bell Beaker culture, like the local production of shaft-hole axes, typologically linked to the Balkans and the Danube region. The site also shows the oldest evidence of ritual burnt offerings in the Eastern Alps. The mostly burnt animal bones, cereals, flint tools and fragments of pottery could be interpreted as the remains of a rock sanctuary with burnt offerings. The site can be considered as a prototype of the alpine places of worship and mountain sanctuaries. These burning rituals were practised from the beginning of the Bronze Age until the late Roman Empire. The aim of the paper is to present the results of the study of materials and their analyses, focussing on the metallurgical industry, composed mostly by objects produced with local copper, like 10 miniaturised shaft-hole axes, 7 awls and a pin and also by imported objects like a dagger blade and spiral ornaments. The deposition of copper tools in hoards in association with burnt offerings suggest a ritual interpretation of the site, dated to the late Copper Age with Bell Beaker elements in lithics and pottery.

This thesis investigates the differences in the design process when developing a product for additive manufacturing (AM) compared to traditional manufacturing methods, such as CNC machining. In recent years, additive manufacturing (AM), including metal-based laser powder bed fusion (L-PBF), has gained popularity, leading to increased adoption by companies. The design process for AM, particularly in the context of metals, differs compared to for traditional manufacturing methods. L-PBF, being a method based on highly concentrated laser beam fusion, offers a higher level of design freedom, enabling the creation of intricate shapes, internal structures, and varying wall thicknesses. In contrast, traditional manufacturing methods based on subtractive processes impose limitations on design possibilities due to tooling and machining constraints. Adapting to L-PBF requires designers to reconsider, re-think and redesign parts specifically for AM, taking into account factors suchas cost, knowledge requirements and build volume limitations. The application of L-PBF extends to various industries, including aerospace and performance automobiles. Designing for L-PBF opens up new possibilities for product development by leveraging the advantages of AM, such as design flexibility and topology optimization. Topology optimization allows for the creation of lightweight components while maintaining structural integrity. However, transitioning from traditional manufacturing to L-PBF presents challenges, requiring designers to navigate the unique considerations and constraints associated with AM. This research aims to enhance the understanding of the design process for AM, with a specific focus on L-PBF, and its implications for product development. By exploring the differences between AM and traditional manufacturing methods, this study contributes to the broader adoption and effective implementation of AM technologies in various manufacturing sectors. / Detta arbete undersöker skillnaderna i designprocessen vid utveckling av produkter för additive manufacturing (AM) jämfört med traditionella tillverkningsmetoder, såsom CNC bearbetning. På senare år har additiv tillverkning (AM), inklusive Laser Powder Bed Fusion (L-PBF), blivit populärt och allt fler företag använder sig av tekniken. Designprocessen för AM, skiljer sig jämnfört med för traditionella tillverkningsmetoder. L-PBF erbjuder en hög grad av designfrihet och möjliggör avancerade former, interna strukturer och varierande väggtjocklekar. I kontrast begränsar traditionella tillverkningsmetoder, som bygger på subtraktiva processer, designmöjligheterna på grund av verktygs- och bearbetningsbegränsningar. Att anpassa sig till L-PBF kräver att designers omprövar och omdesignar delar specifikt för AM och tar hänsyn till faktorer som kostnad, kunskapskrav och begränsningar i byggvolymen. Användningen av L-PBF sträcker sig till olika branscher, inklusive luft- och rymdindustrin samt prestandabilar. Att designa för L-PBF öppnar upp nya möjligheter för produktutveckling genom att utnyttja fördelarna med AM, såsom designflexibilitet och topologioptimering. Topologioptimering möjliggör skapandet av lätta komponenter samtidigt som den strukturella integriteten bibehålls. Övergången från traditionell tillverkning till L-PBF innebär dock utmaningar och kräver att designers hanterar de unika övervägandena och begränsningarna som är förknippade med AM. Denna forskning syftar till att förbättra förståelsen för designprocessen för AM, med särskilt fokus på L-PBF, och dess implikationer för produktutveckling. Genom att utforska skillnaderna mellan AM och traditionella tillverkningsmetoder bidrar denna studie till en bredare användning och effektiv implementering av AM-teknologier inom olika tillverkningssektorer.

Lasers are increasingly used for a wide range of different applications for both civil and military purposes. Due to the distinct properties of laser light, use of lasers often comes with a risk of damage to the human eye and other optical sensors. Therefore, an effective laser protection is needed. 2D-materials is a relatively new class of materials, which have shown to possess many unique properties compared to its bulk counterparts. Some 2D-materials exhibit nonlinear optical (NLO) properties, and specifically optical power limiting (OPL) effects, and have therefore been researched for laser protection applications. In this work, two different 2D-materials, MXene Ti3C2 and graphene oxide (GO), have been combined with a hybrid organic-inorganic polymer, a so called melting gel (MG), to synthesise nanocomposites possessing OPL effects for laser protection applications. Different methods of incorporating the 2D-materials in the polymer matrix as well as the effect on optical properties of different concentrations of 2D-materials were investigated. The prepared nanocomposites were characterised using optical microscopy, spectroscopy and OPL measurements in order to investigate and quantify their linear and nonlinear optical properties. The MG was optically clear, mechanically stable and easy to synthesise, which makes it a suitable candidate as a matrix for a laser protection nanocomposite. Additionally, it was possible to dope the MG with the two different 2D-materials to create nanocomposites showing desirable optical properties in the visible spectrum. However, many samples showed signs of clustered 2D-particles indicating that the dispersion could be improved. Finally, OPL measurements, performed at 532 nm, showed that the MG itself exhibited OPL effects, both 2D-materials showed a stronger OPL effect than the non-doped MG and that GO-doped samples gave a better protection than the MXene samples.