This thesis presents a model for the procedures of manufacturing Fused Fila ment Fabrication (FFF) components by calculating required process parameters using empirical equations. Such an empirical model has been required within the FFF field of research for a considerable amount of time and will allow for an ex pansion in understanding of the fundamental mathematics of FFF. Data acquired through experimentation has allowed for a data set of geometric characteristics to be built up and used to validate the model presented. The research presented draws on previous literature in the fields of additive manufacturing, machine engi neering, tool-path programming, polymer science and rheology. Combining these research fields has allowed for an understanding of the FFF process which has been presented in its simplest form allowing FFF users of all levels to incorporate the empirical model into their work whilst still allowing for the complexity of the process. Initial literature research showed that Polylactic Acid (PLA) is now in common use within the field of FFF and therefore was selected as the main working mate rial for this project. The FFF technique, which combines extrusion and Computer Aided Manufacturing (CAM) techniques, has a relatively recent history with lit tle understood about the fundamental mathematics governing the process. This project aims to rectify the apparent gap in understanding and create a basis upon which to build research for understanding complex FFF techniques and/or pro cesses involving extruding polymer onto surfaces.

Plastics contribute 2 GTons to the global carbon footprint, today, several countries have set targets to achieve carbon neutrality. Plastics, being a major contributor to global carbon footprint, would need to be reduced significantly from our daily life to achieve that or a way needs to be devised to recycle them. A big bottleneck in this process is to reduce the consumption of thermosetting plastics or to reduce the emissions associated with plastic and move towards economical and environmentally safe plastics having a longer lifespan and efficient recyclability. Fused filament fabrication (FFF) is the most commonly used 3D printed technology available today. Its applications range from production of prototypes to hollow shafts, and fully functional commercial components. This technology is revolutionary in a sense that it offers advantages such as cheaper raw materials, high degree of customizability, production in smaller batches at lower costs, decrease in material wastage, rapid prototyping, and complex geometry. A number of thermoplastic polymers can be used with FFF technology to produce parts, in addition research is on going to print materials not commonly used for FFF process. Polyoxymethylene (POM) could be a viable option for utilization as FFF basestock for the production of tribologically functional components. POM is an engineering thermoplastic that offers high resistance to wear, low friction, excellent impact resistance, and good chemical resistance. These properties render it suitable for production of gear wheels and low load bearings. It is currently processed using traditional manufacturing methods such as injection and compression moulding, while its printability has received very little attention in the openly available literature. An attempt has been made in this thesis to fill up this research gap by providing insight into POM filament quality, and the thermal, mechanical, and tribological behaviour of POM printed parts. The influence of overfill and layer height on the bulk properties of the printed samples, its play with counterface surface roughness and applied load has also been investigated.

<div>The work discussed in this document seeks to integrate conductive additives with energetic material systems to offer an alternative source of ignition for the energetic material. By utilizing the conductive properties of the additives, ohmic heating may serve as a method for preheating and igniting an energetic material. This would allow for controlled ignition of the energetic material without the use of a traditional ignition source, and could also result in easier system fabrication.</div><div>For ohmic heating to be a viable method of preheating or igniting these conductive energetic materials, there cannot be significant impact on the energetic properties of the energetic materials. Various mass solids loadings of graphene nanoplatelets (GNPs) were mixed with a reactive mixture of aluminum (Al)/polyvinylidene fluoride (PVDF) to test if ohmic heating ignition was feasible and to inspect the impact that these loadings had on the energetic properties of the Al/PVDF. Results showed that while ohmic heating was a plausible method for igniting the conductive energetic samples, the addition of GNPs degraded the energetic properties of the Al/PVDF. The severity of this degradation was minimized at lower solids loadings of GNPs, but this consequently resulted in larger voltage input requirements to ignite the conductive energetic material. This was attributable to the decreased conductivities of the samples at lower solids loading of GNPs.</div><div>In hopes of conserving the energetic properties of the Al/PVDF while integrating the conductive additives, additive manufacturing techniques, more specifically fused filament fabrication, was used to print two distinct materials, Al/PVDF and a conductive composite, into singular parts. A CraftBot 3 was used to selectively deposit Conductive Graphene PLA (Black Magic) filament with a reactive filament comprised of a PVDF binder with 20% mass solids loadings of aluminum. Various amounts of voltage were applied to these conductive energetic samples to quantify the time to ignition of the Al/PVDF as the applied voltage increased. A negative correlation was discovered between the applied voltage and time to ignition. This result was imperative for demonstrating that the reaction rate could be influenced with the application of higher applied voltages.</div><div>Fused filament fabrication was also used to demonstrate the scalability of the dual printed conductive energetic materials. A flexural test specimen made of the Al/PVDF was printed with an embedded strain gauge made of the Black Magic filament. This printed strain gauge was tested for dual purposes: as an igniter and as a strain sensor, demonstrating the multi-functional use of integrating conductive additives with energetic materials.</div><div>In all, the experiments in this document lay a foundation for utilizing conductive additives with energetic materials to offer an alternative form of ignition. Going forward, ohmic heating ignition may serve as a replacement to current, outdated methods of ignition for heat sensitive energetic materials.</div>

In this thesis, the incorporation of drug loaded mesoporous magnesium carbonate as an excipient for the additive manufacturing of oral tablets by fused deposition modeling was investigated. Cinnarizine, a BCS class II drug, was loaded into the pores of the mesoporous material via a soaking method, corresponding to a drug loading of 8.68 wt%. DSC measurements on the loaded material suggested that the drug was partially crystallized after incorporation, meanwhile the XRD diffractogram implied that the drug was in a state lacking long range order. The drug loaded material was combined with two pharmaceutical polymers, Aquasolve LG and Klucel ELF, and extruded into filaments with a single screw extruder. Filaments of Klucel ELF and drug loaded Upsalite (30:70 wt% ratio) were successfully implemented for the printing oral tablets, in contrast to the Aquasolve LG based filaments which were difficult to print due to thickness variations and non-uniform material distributions. The drug content obtained by TGA suggested drug loadings of 7.71 wt% and 2.23 wt% in the drug loaded Upsalite and tablets respectively. Dissolution studies using an USP II apparatus showed a slower API-release from the tablets in comparison to the crystalline drug, most probably due to slow diffusion of drug species through the polymeric matrix. For future studies, pharmaceutical polymers with higher aqueous solubility should be investigated in order to thoroughly examine the potential of utilizing the immediate release property of Upsalite.

An obstacle to the wide spread use of additive manufacturing (AM) is the difficulty in estimating the effects of process parameters on the mechanical properties of the manufactured part. The complex relationship between the geometry, parameters and mechanical properties makes it impractical to derive an analytical relationship and calls for the use of a numerical model. An approach to formulate a numerical model in developed in this thesis. The AM technique focused in this thesis is fused filament fabrication (FFF). A numerical model is developed by recreating FFF build process in a simulation environment. Machine instructions generated by a slicer to build a part is used to create a numerical model. The model acts as a basis to determine the effects of process parameters on the stiffness and the strength of a part. Determining the stiffness of the part is done by calculating the response of the model to a uniformly distributed load. The strength of the part depends on it's thermal history. The developed numerical model serves as a basis to implement models describing the relation between thermal history and strength. The developed model is suited to optimize FFF parameters as it encompass effects of all FFF parameters. A genetic algorithm is used to optimize the FFF parameters for minimum weight with a minimum stiffness constraint. / Ett hinder för att additiv tillverkning (AT), eller ”3D-printing”, ska få ett bredare genomslag är svårigheten att uppskatta effekterna av processparametrar på den tillverkade produktens mekaniska prestanda. Det komplexa förhållandet mellan geometri och processparametrar gör det opraktiskt och komplicerat att härleda analytiska uttryck för att förutsäga de mekaniska egenskaperna. Alternativet är att istället använda numeriska modeller. Huvudsyftet med denna avhandling har därför varit att utveckla en numerisk modell som kan användas för att förutsäga de mekaniska egenskaperna för detaljer tillverkade genom AT. AT-tekniken som avses är inriktad på Fused Filament Fabrication (FFF). En numerisk modell har utvecklats genom att återskapa FFF-byggprocessen i en simuleringsmiljö. Instruktioner (skriven i GCode) som används för att bygga en detalj genom FFF har här översatts till en numerisk FE-modell. Modellen används sen för att bestämma effekterna av processparametrar på styvheten och styrkan hos den tillverkade detaljen. I detta arbete har strukturstyvheten hos olika detaljer beräknats genom att utvärdera modellens svar för jämnt fördelade belastningsfall. Styrkan, vilket är starkt beroende på den tillverkade detaljens termiska historia, har inte utvärderats. Den utvecklade numeriska modellen kan dock fungera som underlag för implementering av modeller som beskriver relationen mellan termisk historia och styrka. Den utvecklade modellen är anpassad för optimering av FFF-parametrar då den omfattar effekterna av alla FFF-parametrar. En genetisk algoritm har använts i detta arbete för att optimera parametrarna med avseende på vikt för en given strukturstyvhet.

Exoskeletons are wearable devices that enhance or supplement the user’s natural abilities. They have been demonstrated to be efective in alleviating pain, reducing work related injuries, improving working conditions, and can play a pivotal role in improving recovery times and recovery outcomes. Commercial exoskeletons are expensive, specialised and not easily accessible to the average user. This thesis describes the design and manufacturing processes for the OpenXO, an open-source knee exoskeleton. The focus of the thesis is the design and manufacture of the exoskeleton drive system. It implements a cycloidal drive design. Additionally, a method of designing tapered crossed roller bearings was developed that allows for easy integration into elements of the drive system. The open source aspect is further supported by designing the OpenXO around commercially available additive manufacturing technologies. Rapid prototyping and iterative test-based design methods were used in conjunction with empirical testing and validation of both the design and manufacturing methods. Performance validations were conducted on an unpowered exoskeleton. The tests focus on ease of use and comfort. Validation on the exoskeleton and its components was performed at various stages during the design process. The resulting drive design was signifcantly lighter than commercially available solutions. The stator design implemented allows for press ft accuracy between the rotor and stator while allowing for smooth rotation. The fully assembled exoskeleton was tested by 5 individuals. All participants performed tasks to test the usability the exoskeleton in common day to day activities. The participants managed to perform several tasks with ease. However, the exoskeleton was prone to misalignment in specifc circumstances. Gait analysis on a user wearing the exoskeleton shows that the exoskeleton does infuence gait patterns. However, the user does not experience signifcant impact on their perceived range of motion. These tests do not demonstrate the efectiveness of the exoskeleton when it comes to powered assistance. Further work is needed to test and validate the powered assist functionality of the exoskeleton. / Eksoskeletonit ovat puettavia laitteita, jotka parantavat tai täydentävät käyttäjän luonnollisia kykyjä. Niiden on osoitettu olevan tehokkaita kipujen lievittämisessä, työtapaturmien vähentämisessä, työolosuhteiden parantamisessa ja niillä voi olla keskeinen rooli paranemisaikojen ja toipumistulosten parantamisessa. Kaupalliset eksoskeletonit ovat kalliita, erikoistuneita eivätkä tavallisen käyttäjän helposti saatavilla. Tämä opinnäytetyö kuvaa avoimen lähdekoodin polven eksoskeleton OpenXO:n suunnittelu-ja valmistusprosessit. Erityisesti painopiste on sykloidiseen käyttöjärjestelmään perustuvan ulkopuolisen tukirankajärjestelmän suunnittelussa ja valmistuksessa. Lisäksi kartiorullalaakereiden suunnittelumenetelmä kehitettiin siten, että se mahdollistaa helpon integroinnin käyttöjärjestelmän elementteihin. Avoimen lähdekoodin näkökulmaa tuetaan edelleen suunnittelemalla OpenXO kaupallisesti saatavilla olevien lisäaineiden valmistustekniikoiden ympärille. Nopeaa prototyyppiä ja iteratiivisia testipohjaisia suunnittelumenetelmiä käytettiin sekä suunnittelu-että valmistusmenetelmien empiirisen testauksen ja validoinnin yhteydessä. Suorituskyvyn validointi suoritettiin tehottomalla eksoskeletonilla 5 vapaaehtoisen poolissa. Testit suuntautuivat arjen yleisten toimintojen ympärille ja keskittyivät pääasiassa helppokäyttöisyyteen ja käyttömukavuuteen. Eksoskeleton ja sen komponenttien validointi suoritettiin suunnitteluprosessin eri vaiheissa. Tuloksena saatu käyttörakenne oli huomattavasti kevyempi kuin kaupallisesti saatavilla olevat ratkaisut. Toteutettu staattorin rakenne mahdollisti roottorin ja staattorin välisen puristussovituksen tarkkuuden säilyttäen samalla tasaisen pyörimisen. Osallistujat onnistuivat suorittamaan suurimman osan tehtävistä helposti. Eksoskeleton oli kuitenkin altis kohdistusvirheelle tietyissä olosuhteissa. Eksoskeletonia käyttävän käyttäjän kävelyanalyysi osoittaa, että ulkoinen luuranko vaikuttaa kävelykuvioihin, mutta käyttäjä ei koe merkittävää vaikutusta havaittuun liikerataan. Siitä huolimatta tarvitaan lisätyötä eksoskeletonin tehollisen aputoiminnon testaamiseksi ja validoimiseksi. / <p>Presentation conducted online via the Zoom video conferencing platform.</p>