Passive and compact heat dissipation systems are and will remain vital for the successful operation of modern electronic systems. Oscillating heat pipes (OHPs) have been a part of this research area since their inception due to their ability to passively manage high heat fluxes. In the current investigation, different designs of tubular, flat plate, and multiple layer oscillating heat pipes are studied by using different operating parameters to investigate the operating limitations of each design. Furthermore, selective laser melting was demonstrated as a new OHP manufacturing technique and was used to create a compact multiple layer flat plate OHP. A 7-turn tubular oscillating heat pipe (T-OHP) was created and tested experimentally with three working fluids (water, acetone, and n-pentane) and different orientations (horizontal, vertical top heating, and vertical bottom heating). For vertical, T-OHP was tested with the condenser at 0°, 45° and 90° bend angle from the y-axis (achieved by bending the OHP in the adiabatic) in both bottom and top heating modes. The results show that T-OHP thermal performance depends on the bend angle, working fluid, and orientation. Another design of L-shape closed loop square microchannel (750 x 750 microns) copper heat pipe was fabricated from copper to create a thermal connector with thermal resistance < 0.09 ˚C/W for electronic boards. The TC-OHP was able to manage heat rates up to 250 W. A laser powder bed fusion (L-PBF) additive manufacturing (AM) method was employed for fabricating a multi-layered, Ti-6Al-4V oscillating heat pipe (ML-OHP). The 50.8 x 38.1 x 15.75 mm3 ML-OHP consisted of four inter-connected layers of circular mini-channels, as well an integrated, hermetic-grade fill port. A series of experiments were conducted to characterize the ML-OHP thermal performance by varying power input (up to 50 W), working fluid (water, acetone, NovecTM 7200, and n-pentane), and operating orientation (vertical bottom-heating, horizontal, and vertical top-heating). The ML-OHP was found to operate effectively for all working fluids and orientations investigated, demonstrating that the OHP can function in a multi-layered form, and further indicating that one can ‘stack’ multiple, interconnected OHPs within flat media for increased thermal management.

The goal of this study is to investigate the microstructure and microstructure-based fatigue (MSF) model of additively-manufactured (AM) metallic materials. Several challenges associated with different metals produced through additive manufacturing (Laser Enhanced Net Shaping – LENS®) have been addressed experimentally and numerically. Significant research efforts are focused on optimizing the process parameters for AM manufacturing; however, achieving a homogenous, defectree AM product immediately after its fabrication without postabrication processing has not been fully established yet. Thus, in order to adopt AM materials for applications, a thorough understanding of the impact of AM process parameters on the mechanical behavior of AM parts based on their resultant microstructure is required. Therefore, experiments in this study elucidate the effects of process parameters – i.e. laser power, traverse speed and powder feed rate – on the microstructural characteristics and mechanical properties of AM specimens. A majority of fatigue data in the literature are on rotation/bending test of wrought specimens; however, few studies examined the fatigue behavior of AM specimens. So, investigating the fatigue resistance and failure mechanism of AM specimens fabricated via LENS® is crucial. Finally, a microstructure-based MultiStage Fatigue (MSF) model for AM specimens is proposed. For calibration of the model, fatigue experiments were exploited to determine structure-property relations for an AM alloy. Additional modifications to the microstructurally-based MSF Model were implemented based on microstructural analysis of the fracture surfaces – e.g. grain misorientation and grain orientation angles were added to the MSF code.

Additive manufacturing is becoming a leading technology in the production of consumer parts. In order to compete with traditional methods which have had years to improve, additive systems must achieve a level of performance efficiency greater than it maintains today. While great effort is being expended to improve the printing time and add more systems level thinking to the problem, it is currently lacking a robust improvement methodology. To achieve the desired improvement, a technique from traditional manufacturing based on overall equipment effectiveness (OEE) is proposed. Overall additive manufacturing effectiveness (OAME) provides a methodology for enhancing this important emerging technology.

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PhD Thesis / Cardiac surgeons rely on simulation training to improve their surgical skills. The focus of this research was on creating a 3D aortic valve model for cardiac surgical skills training. The research was divided into four different stages including CAD model development, tissue testing using surgical tools, aortic valve model manufacturing and model evaluation. First, the development of a patient-specific aortic valve model was carried out. The process involved heavily processing CT scanned data of the aortic valve to extract the geometric information via segmentation. Patient-specific models are critical for pre-operative planning and training. However, those models are not ideal for large volume quantities due to the high production costs and the extensive manual labour required to process the models. Therefore, another approach was chosen to produce a generic model that was more suitable for large volume quantities. The generic aortic valve model was developed using data obtained from the literature. The contribution in this stage was developing the methodology to reverse engineer patient-specific cardiac tissues. Additionally, a generic CAD model of the aortic valve was developed. Second, to select suitable materials for the model, samples from biological tissues and polymers were tested using a surgical tool. The contribution in this stage was documenting the forces and displacements obtained from puncturing and cutting the samples using suturing needles and scalpel blades. Third, the aortic valve model was manufactured using two approaches including AM and casting. The contribution in this stage revolved around the development of several moulds for casting. Finally, evaluation of the model was done via an initial assessment session with surgical residents. Although the model was not evaluated in extensive training sessions, a plan highlighting the important elements to do that was included in this research. Thus, the contribution in this stage was developing the model testing plan. / Thesis / Doctor of Philosophy (PhD) / Typically, surgeons use post-mortem human tissues (cadavers) and animal tissues for surgical skills training. However, those methods can be both expensive and limited in availability. Therefore, other non-biological methods are introduced constantly to provide viable alternatives. Those methods include producing models using 3D printing, virtual reality (VR) simulation and even using household items to create training models. However, to date, there is a lack of highly accurate representation of real tissues (fidelity) of most models for cardiac surgical training. The purpose of this research was to develop and manufacture surgical skill training tools for cardiac surgeons focusing on the aortic valve cardiac tissues. The research was divided into several parts including developing computer models using patient-specific medical imaging, developing a general training model and training models manufacturing. Also, the research included manufacturing materials selection process as well as plans for testing the training models in training sessions.

Innovation genom additiv tillverkning sker snabbt i dagens industri där snabb prototyptillverkning är något som additiv tillverkning lämpar sig bäst för. Däremot utforskas möjligheter för tillverkning av detaljer med funktionellt syfte då additiv tillverkning möjliggör mer komplicerad design än traditionella tillverkningsmetoder. Med de miljöproblem som förekommer i dagens samhälle ger det upphov till extrema väderförhållanden, exempelvis skogsbränder. Givet det så har detta projekt utforskat möjligheten av att genom additiv tillverkning konstruera en sula med ett inbyggt kylsystem i syfte att kyla foten under förlängd arbetstid i omgivning med hög temperatur. Kravet som ställdes på sulan var att i en omgivning med hög temperatur skall sulan kunna kyla mer än en traditionell sula över en period på 8 timmar. Med hjälp av CAD- och FEM-program analyserades tre primära modeller med avseende på temperaturutväxling samt belastning, varav dessa tre modeller ställdes i relation till en traditionell sula utan kylsystem. Resultaten hänvisar till att med de krav som ställdes på sulan ges en högre kylningseffekt vid två av tre av dessa modeller relativt en traditionell sula. Dessutom finns potential för fortsatt utveckling av liknande sulor med avseende på specialtillverkning. / Innovation through additive manufacturing occurs quickly in today’s industry where rapid prototyping is something that additive manufacturing excels at. However, research is being made to explore the ability for manufacturing components with functional use, where additive manufacturing makes more complex design possible in relation to traditional manufacturing methods. With the environmental problem that occurs in today’s world comes more extreme weather conditions, for example forest fires. With that as a basis, this project has explored the possibility of creating the sole of a shoe with a built-in cooling system, using additive manufacturing, for the purpose of extended work in an environment with a high temperature. The requirements put on the sole was that in an environment of high temperature the sole should be able to help reduce temperature inside the shoe itself over the course of an eight-hour workday. Three primary models were analysed in terms of transient temperature as well as load and deformation with the help of CAD and FEM programs, where these three soles were compared to a sole without any form of cooling system. The results show that with the parameters of the project, a greater cooling effect is achieved in two of the three models, compared to a regular sole. Furthermore, there is the potential for continued development of similar models of soles with respect to specific demands in fields such as hiking.

Additive Manufacturing (AM) is another name for rapid prototyping and 3D printing (3DP), an advanced manufacturing technology that creates 3D objects. AM's ability to produce complex shapes in industrial production is one of its chief advantages. AM is spreading to different areas in healthcare and is being considered a disruptive innovation that is changing orthopedics.  However, integrating AM into daily orthopedic practice remains a challenging task. This thesis aims to explore clinicians' views on the adoption of AM implants, surgical guides and accessories as well as investigating which way do regulations and policies affect the adoption of 3DP in the orthopedic industry in Sweden. Apart from reviewing existing literature contemplated on factors that affect the adoption of AM in an industry, in this study, a qualitative research approach have been used. A semi-structured interview has been applied to all the seven orthopedic surgeons who participated in the research. Using a thematic analysis approach, the data have been analyzed to address the thesis research questions.    According to the thesis findings, AM adoption in the orthopedic sector is influenced by a number of factors. With the technology, organization, and environment (TOE framework) there are classified into three main contexts. The study used the findings along with the TOE model, which embeds the regulation factor within an environmental context. The findings indicate that the medical device regulation (MDR) affects the adoption of medical devices both positively and negatively in the orthopedic industry in Sweden.  Technologically, the dilemma and challenge of adopting AM is influenced by the lack of resources in the healthcare field which also influence the organization context. It is the viewpoint of the buyer that orthopedists and hospitals have when it comes to adoption of AM. This means that the trading factor expressed in the environment context is another driving factor for AM adoption. By using the Kraljic model, AM technology has been classified as a strategic item. The procurement and purchase efforts should focus on establishing a long-term relationship with a single manufacturing company and both aiming to combine effort and resources to reduce total costs. In conclusion, The implementation of AM in orthopedic practice will be possible as long as all factors are taken into account. In orthopedic practice, AM should be used to create surgical guides, 3D models for surgical planning, and custom implants.

In this thesis, support structures of a polymer powder based process called XXXXXXXX™ are examined. These structures are crucial for most additive manufacturing processes. The effects of several factors on five industrially important characteristics of support structures are examined by use of the Design of Experiment (DoE) method. It describes the planning as well as the analysis of the experiments. The experiments are planned in a fractional factorial 211-5 design with 64 specimens, resulting in a resolution of IV. The analysis of the data is done by use of the ANOVA method, with which the significance of effects and interaction effects are checked. / I detta examensarbete undersöks stödstrukturer för en polymer-pulverbaserad process kallad XXXXXXXX. Dessa strukturer är väsentliga för de flesta aditiv tillverkning. Med hjälp av metoden "Design of Experiment" (DoE) undersöks effekten av flera faktorer på fem industriellt viktiga egenskaper för stödstrukturer. DoE beskriver både planeringen och analysen av experiment. Experimenten planeras i en fraktionerad faktoriell 211-5 design med 64 provexemplar vilket resulterar i en upplösning av IV. Dataanalysen genomförs med hjälp av ANOVA-metoden, med vilken signifikansen av effekter och interaktionseffekter kan undersökas.

Additive Manufacturing – AM – which is a part of a generic term, Rapid Prototyping, comprises a family of different techniques to build 3D physical objects sequentially stacking a series of layers over each other. These techniques have been evolving over three decades with more materials available, improving the techniques as well as generating new ones. However they are all based on the same explained idea. In this research the main AM methods followed with the opportunities of application and cost drivers is sought. For this purpose, after reviewing different processes and techniques, the application of them in diverse industry sectors is described. The influence of AM in production systems, so called Rapid Manufacturing (RM) is also discussed in terms of lean and agile concepts. Time and cost are the most important factors for the production systems to be responsive and productive respectively. Thus, case based application of RM is evaluated to clarify how AM acts in different production systems regarding these factors. To decide which method is the best, strongly depends on the case. But what has been derived from the analysis, is that however in comparison with traditional methods, AM applies more economically in one-off jobbing, yet the economy of scale exists to some extent. In fact it depends on the machine capacity utilization as well as batch size which indicates the machine volume usage. Despite all the improvements in the last three decades, the application of AM is still not widespread. Since the demand, use, applications and materials as well as its techniques are still in a growing phase, a brighter future is seen for the upcoming customer oriented market. / Additive Manufacturing – AM – som är del av en generell term, Rapid Prototyping, består av en familj olika tekniker för att bygga 3D fysiska objekt genom att sekventiellt lägga lager ovanpå varandra. Dessa tekniker har utvecklats över de senaste tre decennierna, där nya material blivit tillgängliga, teknikerna har förbättrats och nya har skapats, men i slutändan bygger de alla på en och samma idé. Det projekt undersöks de huvudsakliga AM -metoderna, deras applikationer och kostnadsdrivare. Här görs först en litteraturstudie av olika tekniker och processer varefter deras användning inom olika industrier undersöks. Den influens AM har i produktionssystem, s.k. Rapid Manufacturing (RM), diskuteras också i förhållande till lean och agila koncept. Eftersom tid och kostnad är de viktigaste faktorerna för tillgänglighet respektive produktivitet utvärderas case-baserad användning av RM utifrån dessa faktorer för att förklara hur AM fungerar i produktionssystem. Att besluta vilken metod som är bäst, är starkt case-baserad. Men det som framkommit från analysen är att i jämförelse med traditionella metoder, är AM mer ekonomiskt vid enstyckstillverkning, men stordriftsfördelar finns i någon utsträckning. Faktiskt det beror på maskinens kapacitetsanvändning och satsstorlek som indikerar maskinens volymanvändning. Trots alla förbättringar under de senaste tre decennierna är användandet av AM ännu inte utbrett. Eftersom efterfrågan, användning, tillämpning och material så väl som dess tekniker fortfarande befinner sig i en tillväxtfas spås en ljusare framtid för en växande kundorienterad marknad.

Additive friction stir deposition is characterized by rotating a consumable feedstock rod that induces severe plastic deformation to deposit material additively without raising the material past its melting point. In this way, additive friction stir deposition differs from traditional additive manufacturing, and new developments in this technology require further investigation of build parameters, tooling, and resultant builds to better understand this printing process and its applications. This thesis evaluated the effect of rotational speed on aluminum 6061 builds using mechanical testing and microstructural investigations. Three different build conditions were evaluated at 180 RPM, 240 RPM, and 300 RPM. Mechanical testing methods were used to determine hardness values, ultimate tensile strength, yield strength, elastic modulus, and density. Imaging techniques including optical microscopy, electron backscatter diffraction, energy dispersive x-ray spectroscopy, and x-ray computed tomography were used to evaluate microstructure, grain size, chemical composition, and porosity.