The aim of this master thesis project was to statistically correlate various powder characteristics to the quality of additively manufactured parts. An additional goal of this project was to find a potential second source supplier of powder for GKN Aerospace Sweden in Trollhättan. Five Inconel® alloy 718 powders from four individual powder suppliers have been analyzed in this project regarding powder characteristics such as: morphology, porosity, size distribution, flowability and bulk properties. One powder out of the five, Powder C, is currently used in production at GKN and functions as a reference. The five powders were additively manufactured by the process of laser metal deposition according to a pre-programmed model utilized at GKN Aerospace Sweden in Trollhättan. Five plates were produced per powder and each cut to obtain three area sections to analyze, giving a total of fifteen area sections per powder. The quality of deposited parts was assessed by means of their porosity content, powder efficiency, geometry and microstructure. The final step was to statistically evaluate the results through the analysis methods of Analysis of Variance (ANOVA) and simple linear regression with the software Minitab. The method of ANOVA found a statistical significant difference between the five powders regarding their experimental results. This made it possible to compare the five powders against each other. Statistical correlations by simple linear regression analysis were found between various powder characteristics and quality of deposited part. This led to the conclusion that GKN should consider additions to current powder material specification by powder characteristics such as: particle morphology, powder porosity and flowability measurements by a rheometer. One powder was found to have the potential of becoming a second source supplier to GKN, namely Powder A. Powder A had overall good powder properties such as smooth and spherical particles, high particle density at 99,94% and good flowability. The deposited parts with Powder A also showed the lowest amount of pores compared to Powder C, a total of 78 in all five plates, and sufficient powder efficiency at 81,6%.

There is growing interest in using additive manufacturing for various alloy systems and industrial applications. However, existing process development and part qualification techniques, both involve extensive experimentation-based procedures which are expensive and time-consuming. Recent developments in understanding the process control show promise toward the efforts to address these challenges. The current research uses the process mapping approach to achieve control of melt pool geometry and microstructure in different alloy systems, in addition to location specific control of microstructure in an additively manufactured part. Specifically, results demonstrate three levels of microstructure control, starting with the prior beta grain size control in Ti-6Al-4V, followed by cell (solidification structure) spacing control in AlSi10Mg, and ending with texture control in Inconel 718. Additionally, a prediction framework has been presented, that can be used to enable a preliminary understanding of melt pool geometry for different materials and process conditions with minimal experimentation. Overall, the work presented in this thesis has the potential to reduce the process development and part qualification time, enabling the wider adoption and use of additive manufacturing in industry.

Master of Science / Department of Mechanical and Nuclear Engineering / Gurpreet Singh / 3D-printing is a popular manufacturing technique for making complex parts or small quantity batches. Currently, the applications of 3D-printing are limited by the material properties of the printed material. The processing parameters of commonly available 3D printing processes constrain the materials used to a small set of primarily plastic materials, which have relatively low strength and electrical conductivity. Adding filler materials has the potential to improve these properties and expand the applications of 3D printed material. Carbon nanomaterials show promise as filler materials due to their extremely high conductivity, strength, and surface area. In this work, Graphite, Carbon Nanotubes, and Carbon Black (CB) were mixed with raw Acrylonitrile Butadiene Styrene (ABS) pellets. The resulting mixture was extruded to form a composite filament. Tensile test specimens and electrical conductivity specimens were manufactured by Fused Deposition Method (FDM) 3D-printing using this composite filament as the feedstock material. Weight percentages of filler materials were varied from 0-20 wt% to see the effect of increasing filler loading on the composite materials. Additional tensile test specimens were fabricated and post-processed with heat and microwave irradiation in attempt to improve adhesion between layers of the 3D-printed materials. Electrical Impedance Spectroscopy tests on 15 wt% Multiwalled Carbon Nanotube (MWCNT) composite specimens showed an increase in DC electrical conductivity of over 6 orders of magnitude compared to neat ABS samples. This 15 wt% specimen had DC electrical conductivity of 8.74x10−6 S/cm, indicating semi-conducting behavior. MWCNT specimens with under 5 wt% filler loading and Graphite specimens with under 1 wt% filler loading showed strong insulating behavior similar to neat ABS. Tensile tests showed increases in tensile strength at 5 wt% CB and 0.5 wt% MWCNT. Placing the specimens in the oven at 135 °C for an hour caused increased the stiffness of the composite specimens.

Die Additive Fertigung spielt heutzutage auch in der Automobilindustrie eine bedeutende Rolle. Eine Ausprägungsform, das pulverbett-basierte LaserCUSING®-Verfahren, bietet viele neue Möglichkeiten. Im Folgenden wird zunächst ein kurzer Überblick über das Verfahren gegeben und anschließend der Einsatz des LaserCUSING®s im Bereich Automotive anhand eines gemeinsamen Projekts der EDAG Engineering GmbH, des Laser Zentrums Nord, der BLM Group und der Concept Laser GmbH verdeutlicht. Hier wurde auf Basis des EDAG Light Cocoon ein topologisch optimierter und hybrid gefertigter Spaceframe entwickelt. Die Karosserieknoten wurden mittels LaserCUSING® additiv hergestellt.

Additive manufacturing (AM) offers a way to manufacture highly complex designs with potentially enhanced performance as it is free from many of the constraints associated with traditional manufacturing. However, current design and optimisation tools, which were developed much earlier than AM, do not allow efficient exploration of AM's design space. Among these tools are a set of numerical methods/algorithms often used in the field of structural optimisation called topology optimisation (TO). These powerful techniques emerged in the 1980s and have since been used to achieve structural solutions with superior performance to those of other types of structural optimisation. However, such solutions are often constrained during optimisation to minimise structural complexities, thereby, ensuring that solutions can be manufactured via traditional manufacturing methods. With the advent of AM, it is necessary to restructure these techniques to maximise AM's capabilities. Such restructuring should involve identification and relaxation of the optimisation constraints within the TO algorithms that restrict design for AM. These constraints include the initial design, optimisation parameters and mesh characteristics of the optimisation problem being solved. A typical TO with certain mesh characteristics would involve the movement of an assumed initial design to another with improved structural performance. It was anticipated that the complexity and performance of a solution would be affected by the optimisation constraints. This work restructured a TO algorithm called the bidirectional evolutionary structural optimisation (BESO) for AM. MATLAB and MSC Nastran were coupled to study and investigate BESO for both two and three dimensional problems. It was observed that certain parametric values promote the realization of complex structures and this could be further enhanced by including an adaptive meshing strategy (AMS) in the TO. Such a strategy reduced the degrees of freedom initially required for this solution quality without the AMS.

In this work, melt pool size in process mapped in power-velocity space for multiple processes and alloys. In the electron beam wire feed and laser powder feed processes, melt pool dimensions are then related to microstructure in the Ti-6Al-4V alloy. In the electron beam wire feed process, work by previous authors that related prior beta grain size to melt pool area is extended and a control scheme is suggested. In the laser powder feed process, in situ thermal imaging is used to monitor melt pool length. Real time melt pool length measurements are used in feedback control to manipulate the resulting microstructure. In laser and electron beam direct metal additive manufacturing, characteristics of the individual melt pool and the resulting final parts are a product of a variety of process parameters. Laser or electron beam spot size is an important input parameter that can affect the size and shape of a melt pool, and has a direct influence on the formation of lack-of-fusion and keyholing porosity. In this work, models are developed to gain a better understanding of the effects of spot size across different alloys and processes. Models are validated through experiments that also span multiple processes and alloys. Methods to expand the usable processing space are demonstrated in the ProX 200 laser powder bed fusion process. In depth knowledge of process parameters can reduce the occurrence of porosity and flaws throughout processing space and allow for the increased use of non-standard parameter sets. Knowledge of the effects of spot size and other process parameters can enable an operator to expand the usable processing space while avoiding the formation of some types of flaws. Based on simulation and experimental results, regions where potential problems may occur are identified and process parameter based solutions are suggested. Methods to expand the usable processing space are demonstrated in the ProX 200 laser powder bed fusion process. In depth knowledge of process parameters can reduce the occurrence of porosity and flaws throughout processing space and allow for the increased use of non-standard parameter sets.

After the development of additive manufacturing technology in the 1980s, it has found use in many applications like aerospace, automotive, marine, machinery, consumer and electronic applications. In recent time, few researchers have worked on the applications of additive manufacturing for heat transfer and fluidic devices. As the world has seen a drastic increase in population in last decades which have put stress on already scarce energy resources, optimization of energy devices which include energy storing devices, heat transfer devices, energy capturing devices etc. is need for the hour. Design of energy devices is often constrained by manufacturing constraints thus current design of energy devices is not an optimized one. In this research we want to conceptualize, design and manufacture optimized heat transfer and fluidic devices by exploiting the advantages provided by additive manufacturing. We want to benefit from the fact that very intricate geometry and desired surface finish can be obtained by using additive manufacturing. Additionally, we want to compare the efficacy of our designed device with conventional devices. Work on usage of Additive manufacturing for increasing efficiency of heat transfer devices can be found in the literature. We want to extend this approach to other heat transfer devices especially tubes with internal flow. By optimizing the design of energy systems we hope to solve current energy shortage and help conserve energy for future generation.We will also extend the application of additive manufacturing technology to fabricate "device for uniform flow distribution".

Microstructure controls many physical properties of a material such as strength, ductility, 1density, conductivity, which, in turn, determine the application of these materials. This thesis work focuses on studying microstructural features (such as grain size, shape, defects, orientation gradients) and mechanical properties (such as hardness and yield strength) of multilayered materials that have undergone different loading and/or operating conditions. Two materials that are studied in detail are 18 nm Cu-Nb nanolaminates and 3D printed Inconel 718. Copper-Niobium (Cu-Nb) nanolaminate is a highly stable, high strength, nuclear irradiation resistant composite, which is destabilized with application of high pressure torsion (HPT). This work focuses on understanding the deformation and failure behavior of Cu-Nb using a novel orientation mapping technique in transmission electron microscopy in (TEM) called Automated Crystal Orientation Mapping (ACOM) and Digistar (ASTARTM) or Precession Electron Diffraction (PED). A new theory is postulated to explain strengthening mechanisms at the nanoscale using a data analytics approach. In-situ TEM compression and tensile testing is performed to image dislocation movement with the application of strain. This experiment was performed by Dr. Lakshmi Narayan Ramasubramanian at Xi’an Jiaotong University in China. Another major aspect of this research focuses on the design, fabrication, and microstructural characterization of 3D printed Inconel 718 heat exchangers. Various heat exchanger designs, machine resolution, printing techniques such as build orientation, power, and velocity of the laser beam are explored. Microstructural and mechanical properties of printed parts (before and after heat treatment) are then analyzed to check consistency in grain size, shape, porosity, hardness in relation to build height, scan parameters, and design. Various tools have been utilized such as scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), x-ray computed microtomography (at Advanced Photon Source at Argonne National Lab), hardness and micro-pillar compression testing for this study.

Aim: The aim of this study is to evaluate if additive manufacturing (AM) is an appropriate manufacturing method for insoles in comparison to vacuum forming (VF) and subtractive manufacturing (SM) in regards of material properties such as abrasion resistance. Background: Traditionally insoles are manufactured with either VF or SM. AM has been around for some decades but implementation into orthotic and prosthetic (O&P) business has not been accomplished yet. Therefore, the quality of the products produced with AM must be tested in comparison with traditional methods. Method: A comparison of samples for the mentioned manufacturing methods was done with the help of an abrasion testing machine with the standard ASTM G133. Two samples were produced from each manufacturing method and respectively tested for one and two hours. All the samples were weighed before and after the tests with the help of a four decimal scale. The difference in weight before and after the test and coefficient of friction was evaluated. The weight difference was analyzed to see how much material had been removed from the sample. The percentage of wear loss was calculated for each specific sample, both for one hour and two hours of testing. No statistical analysis could be made due to the limited amount of samples and testing time. Result: No statistically significant could be found for either wear loss or the coefficient of friction as mentioned above. Conclusion: A conclusion whether which material having the best abrasion resistance for respectively manufacturing method could not be drawn due to limited results. This study can be seen as a pilot study where the methodology can be used in further studies. Further research on AM needs to be conducted.

Abstract When we paint a nebulous future of tomorrow based on the research dictated by the available resources, we see a marathon run for the future that instigates new opportunities for the automotive industry with additive manufacturing. Cars of today are a product of subtractive manufacturing; but in future 3D printing would empower us to define a novel architecture that provokes the construction of the interior, exterior and the powertrain in one piece allowing us to celebrate the marriage between all three key components. Project UNO, meaning - ‘one’, exhibits this new architecture through a semi-autonomous concept that exaggerates the feeling of sportiness with a suspended cabin. In the autonomous mode the cabin moves around in the boundary of the exterior to enhance the g-forces by thrusting the cabin forward while accelerating, backward while braking and tilting while cornering. Therefore, the sporty nature of the design can be celebrated actively in both modes. Inspiration and Method The process was cut up into two palpable routes. The former dealt with a system level approach where the present cardinal building blocks of automotive manufacturing were rearranged with the new cues derived from additive manufacturing techniques to render a new system level solution. The later was aimed at advocating a tangible solution that best delineated this idea. Ten radical themes were generated that helped showcase the marriage between the three key components - exterior, interior and powertrain. The final theme was inspired by the analogy of an egg where the yolk moves freely within the egg white. This metaphor was then applied to the cabin experience in the autonomous mode. The occupant in the manual driven mode can cherish the full potential of the car to procure a sporty experience outside the city. While in the city, the autonomous mode seizes control and instigates the movement of the cabin within the perimeter of the exterior to amplify the g-forces by thrusting the cabin forward while accelerating, backwards while braking and tilting it while cornering. Result Concept UNO celebrates the marriage between the exterior, the interior and the powertrain that best encapsulates the process of additive manufacturing where cars would be grown and not assembled. The interior tub is reposed inside the exterior shell with the aid of six mechanical joints and is not adhered to the floor of the car. The gap around the cabin exaggerates the feel of a floating island that can shift freely. The cabin is composed of smart glass which renders opaque when an electric current is passed through it and turns transparent when the car is parked gravitating people to yield a glimpse of the interior. The bottom of the cabin is reflected by the gloss finish of the chassis unit that amplifies the floating feeling. A warm white was used to grant the concept a more puristic look while making it seem warm and friendly. The idea was then showcased through a 1:4 scale model printed in one piece using a Selective Laser Sintering (SLM) technique.