Numerous works have been produced on the topic of Design for Manufacturing (DFM) to better educate the designers of products as to various methods of manufacturing and their specific requirements. It is the common aim of these works to eliminate so called "over the wall" product development in which procedurally ignorant designers pass largely un-producible design concepts to manufacturers, who are then required to make necessary refinements and changes. When applied correctly, DFM results in the efficient and economical production of well-designed products, whose forms have been attuned to the particular requirements of their final method of production at an early stage of development. However, one aspect of using such approaches is that design intent is frequently compromised for the sake of manufacturability and innovative design concepts are often dismissed as being unfeasible. Recent advances in additive manufacturing technologies and their use in the direct manufacture of end-use products from digital data sources has brought about a new method of production that is known as Rapid Manufacturing (RM). Unlike conventional subtractive machining processes, such as milling and turning which generate forms by removing material from a stock billet, RM parts are grown from an empty part bed using the controlled addition of specialised build materials. Additive manufacturing requires no forming tools, is unrestricted by many conventional process considerations and is capable of producing practically any geometry. The freedoms that are associated with this technology facilitate the design and realisation of product concepts that would be unachievable with any other method of production. This promotes an almost boundless design philosophy in which innovative product solutions can be designed to best meet the needs of specification criteria, rather than the production process with which they are to be made. However, unlike other forms of manufacturing, the newness of this technology means that there is no proven aid or tool to assist industrial designers in exploiting the freedoms that it offers. Using information that was collated in the literature review and case study projects, a systematic design approach was proposed and then tested in a series of user trials with groups of industrial design students and practicing industrial design professionals. The results of these trials are discussed, showing a common acknowledgement from both groups that the proposed DFRM tool was of assistance and that it had an influence upon their design work. However, whilst the student group were generally receptive toward tool uptake, the experienced designers showed more of a reluctance to abandon their own "tried and tested" methods in favour of the unknown and unproven approach. It is concluded that this attitude would be fairly representative of wider opinion and that the future uptake of any such tool would be reliant upon sufficient evidence of its successful application. Hence, suggestions are made for future work to continue tool development and for more validation trials to be conducted with its intended user group.

Diploma thesis Use of additive manufacturing in interior product development is focused on researching whether there is a use for 3D printing and related technologies from theoretical as well as from practical site of the issue. It focuses on possibilities of layered manufacturing and related technologies, material possibilities and practical application in the field of interior products. Practical part of the thesis consists of material and component testing.

abstract: As additive manufacturing grows as a cost-effective method of manufacturing, lighter, stronger and more efficient designs emerge. Heat exchangers are one of the most critical thermal devices in the thermal industry. Additive manufacturing brings us a design freedom no other manufacturing technology offers. Advancements in 3D printing lets us reimagine and optimize the performance of the heat exchangers with an incredible design flexibility previously unexplored due to manufacturing constraints. In this research, the additive manufacturing technology and the heat exchanger design are explored to find a unique solution to improve the efficiency of heat exchangers. This includes creating a Triply Periodic Minimal Surface (TPMS) geometry, Schwarz-D in this case, using Mathematica with a flexibility to control the cell size of the models generated. This model is then encased in a closed cubical surface with manifolds for fluid inlets and outlets before 3D printed using the polymer nylon for thermal evaluation. In the extent of this study, the heat exchanger developed is experimentally evaluated. The data obtained are used to derive a relationship between the heat transfer effectiveness and the Number of Transfer Units (NTU).The pressure loss across a fluid channel of the Schwarz D geometry is also studied. The data presented in this study are part of initial experimental evaluation of 3D printed TPMS heat exchangers.Among heat exchangers with similar performance, the Schwarz D geometry is 32% smaller compared to a shell-and-tube heat exchanger. / Dissertation/Thesis / Masters Thesis Mechanical Engineering 2018

Current debates on design and manufacturing support the claim that the ‘Third Industrial Revolution’ has already started due to Additive Manufacturing (AM) and 3D Printing. The process of solidifying liquid or powder using a binding agent or a melting laser can save time and transportation costs associated with importing primary material if locally sourced material is available. This research investigates a framework approach, titled SAFE, for discussing the functionality, economic viability, production feasibility, and aesthetic and cultural value lent by 3D printing on an architectural scale through a construction known as a Mashrabiya. This traditional window screen has distinguished aesthetic, cultural yet functional constraints, and there is a manufacturing gap in the market that makes it a viable product option to be 3D printed. The practical element and design process related to reviving this screen are examined, from complex geometry development to cost and fabrication estimations. 3D printing technologies potentially offer solutions to solve issues in construction and assembly times, reduce labour costs, and address the loss of hand craft making skills in a variety of cultures, typically Middle Eastern ones; this was a factor in the abandonment of old Mashrabiya in houses typified with Bahrain as a case. Presently, there is a growing wealth of literature that highlights not only the strength of Mashrabiya as a design concept but also as a possible 3D printed product. Interviews with a total of 42 local Bahraini manufacturers, academics and architects as well as 4 case studies and 2 surveys and 11 focus groups are hybrid mixed methods used to define a new 3D printed Mashrabiya (3DPM) prototype. The future of the 3D Mashrabiya prototype is further supported by economic forecasts, market research, and interviews with global manufacturers and 3D printing designers’ insights into the subject in an accretive design process. The research contributes to an understanding of the implications of technologies that enable mass customisation in the field of 3D-printed architecture in general and in the Bahraini market in particular. The process for developing a prototype screen and in determining its current economic value will prove significant in predicting the future benefits and obstacles of 3D-printed large scale architectural products in the coming five years as advised by industry experts. The main outcomes relate to establishing boundaries determining the validity of using 3D printing and a SAFE framework to produce a parametric Mashrabiya and other similar heritage architectural archetypes. This can be used to enhance the globalism of the design of Middle Eastern dwellings and to revive social identity and cultural traditions through innovative and reasonable yet superior design solutions using a hybrid architectural design language.

The analysis of microstructural shapes is an underutilized tool in the field of materials science. Typical observations of morphology are qualitative, rather than quantitative, which prevents the identification of relationships between shape and the mechanical properties of a material. Recent advances in the fields of computer vision and high-dimensional analysis have made computer-based shape characterization feasible on a variety of materials. In this work, the relationship between microstructural shapes, and the properties and function of the material as a whole, is explored using moment invariants as global shape descriptors. A diifferent relationship is examined in each of three material systems: how the three-dimensional shapes of cells in the cotyledons of the plant Arabidopsis Thaliana can be used to identify cell function; the two-dimensional shapes of additive manufacturing feedstock powder and the ability to distinguish between images of powders from different samples; and the two-dimensional shapes of ' precipitates and their influence on the creep resistance of single crystal nickel-base superalloys. In the case of Arabidopsis Thaliana cotyledon cells, three-dimensional Zernike and Cartesian moment invariants were used to quantify morphology, and combined with size and orientation information. These feature sets were then analyzed using unsupervised and supervised machine learning methods. Moderate success was found using unsupervised methods, indicating that natural delineations in the data correlate to cell roles to some degree. Using supervised methods, a success rate of 90% was possible, indicating that these features can be used to identify cell function. The ability of two-dimensional Cartesian moment invariants to distinguish meaningful features in particles of additive manufacturing feedstock was tested by using these features to classify images of feedstock. Ultimately, simple histogram matching methods were unsuccessful, likely because they rely on the most common particles to draw conclusions. A bag-of-words method was used, which uses high-dimensional visualization and clustering techniques to classify individual particles by common features. Histograms of particle clusters are then used to represent each image. This method was far more successful, and a correct classification rate of up to 90% was found, and comparable rates were discovered using invariants which describe the shapes only broadly. This indicates that moment invariants are an effective measure of the morphologies of these types of particles, and can be used to classify powder shapes, which control many properties which are relevant to the additive manufacturing process. In the case of the superalloys, it has been shown that the shape distribution of ' precipitates can be tracked using second order moment invariants. In addition, several loworder moment invariants are shown to correlate to creep resistance in four alloys examined, which supports the idea that the shape of precipitates plays role in determining creep resistance in these alloys.

The potential of Additive Manufacturing (AM) for microwave and mm-wave applications is increasingly being revealed thanks to recent advancements in research. AM empowers engineers with new capabilities to manufacture complex conformal geometries quicker and at lower costs. It allows, for instance, the embedding of RF front ends into functional structures. In this dissertation, two aspects of AM are explored: (a) The development and characterization of techniques that improve the performance of AM microwave circuits and antennas, and (b) study of complex geometries, such as meshed structures, as an alternative to reduce material usage, cost, and weight of the components. Micro-dispensing of silver paste (CB028) is extensively used in this work as a viable approach for manufacturing microwave planar transmission lines. However, the performance and upper-frequency range of these lines are limited by the cross-sectional shape and electrical conductivity of the printed paste, as well as the achievable minimum feature size which is typically around 100 μm. In this work a picosecond Nd:YAG laser is used to machine slots in a 20-25 μm-thick layer of silver paste (Dupont CB028) that is micro-dispensed on a Rogers RT5870 substrate, producing coplanar waveguide transmission lines with 16-20 μm-wide slots. It is shown that the laser solidifies 2 μm wide region along the edges of the slots, thus significantly increasing the effective conductivity of the film and improving the attenuation constant of the lines. The extracted attenuation constant at 20 GHz for laser machined CB028 is 0.74 dB/cm. CPW resonators and filters show that the effective conductivity is in the range from 10 MS/m to 30 MS/m, which represents a 100x improvement when compared to the values obtained with the exclusive use of micro-dispensing. Another main aspect of this dissertation is the study of meshed structures in coplanar waveguides. For most AM processes the materials utilized for the conductive layer are the most expensive ones; hence, there is value in minimizing the conductor surface area used in a circuit. In this work, the approach of meshed ground coplanar waveguide (MGCPW) is analyzed by simulating, fabricating and measuring a broad set of meshed ground geometry sizes. Furthermore, a physical-mathematical model is presented, which predicts the characteristic impedance and the capacitance per unit length of MGCPW with less than 5.4% error compared to simulated data. A set of filters is designed and fabricated in order to demonstrate the approach. The main parameter affected by meshing the ground plane is the attenuation constant of the waveguide. It is shown that 50% mesh density in the ground plane of a MGCPW line can be used with less than 25% increase in the loss. In contrast, the loss of finite ground coplanar waveguide (FGCPW) can increase by as much as 108% when the ground size is reduced by the same factor (50%). Both 3D printing (micro-dispensing) and traditional printed circuit board manufacturing are used in this work, and most of the propagation characterization is performed at 4 GHz. A meshing technique is also applied to rectangular waveguides, and its effects are studied. It is presented as an option for high power, low loss, but also reduced weight applications. A set of meshed Ku-band waveguides was fabricated using binder jetting 3D printing technology showing that the weight can be reduced by 22% with an increase in loss of only 5%, from 0.019 dB/cm for the solid part to 0.020 dB/cm average across the band with the meshed design. Further weight reduction is possible if higher loss is allowed. To demonstrate the concept, a comparison is made between non-meshed and meshed waveguide 4 pole Chebyshev filters. Finally, the BJ technology is characterized for Ku-Band rectangular waveguide and reflector antenna applications. This technology is characterized using electron beam microscopy (SEM) and energy dispersive spectroscopy (EDS). The RF performance of the 3D printed circuits is benchmarked with Ka-band cavity resonators, waveguide sections, and a filter. An unloaded resonator Q of 616 is achieved, and the average attenuation of the WR-28 waveguide section is 4.3 dB/m. The BJ technology is tested with a meshed parabolic reflector antenna, where the illuminating horn, waveguide feed, and a filter are printed in a single piece. The antenna shows a peak gain of 24.56 dBi at 35 GHz.

Additive manufacturing (AM) has shown itself to be beneficial in many application areas, including product design and manufacture, medical models and prosthetics, architectural modelling and artistic endeavours. For some of these applications, coupling AM with reverse engineering (RE) enables the utilisation of data from existing 3D shapes. This thesis describes the application of AM and RE within sculpture manufacture, in order to optimise the process chains for sculpture reproduction and relic conservation and restoration. This area poses particular problems since the original artefacts can often be fragile and inaccessible, and the finishing required on the AM replicas is both complex and varied. Several case studies within both literature and practical projects are presented, which cover essential knowledge of producing large scale sculptures from an original models as well as a wide range of artefact shapes and downstream finishing techniques. The combination of digital technologies and traditional art requires interdisciplinary knowledge across engineering and fine art. Also, definitions and requirements (e.g. 'accuracy'), can be applied as both engineering and artistic terms when specifications and trade-offs are being considered. The thesis discusses the feasibility for using these technologies across domains, and explores the potential for developing new market opportunities for AM. It presents and analyses a number of case study projects undertaken by the author with a view to developing cost and time models for various processes used. These models have then been used to develop a series of "process maps", which enable users of AM in this area to decide upon the optimum process route to follow, under various circumstances. The maps were validated and user feedback obtained through the execution of two further sculpture manufacturing projects. The thesis finishes with conclusions about the feasibility of the approach, its constraints, the pros and cons of adopting AM in this area and recommendations for future research.

Energy efficiency has become a growing concern in a world driven by a fossil fuel economy. Recuperated micro-gas-turbine systems offer the possibility of high efficiency power generation for low output power systems. To this end, increasing the performance while decreasing the cost, the weight and the volume of heat exchangers such as recuperators has become a critical research focus. Recent work done by Brayton Energy Canada (BEC) has renewed interest in Wire Mesh Heat Exchangers (WMHE) by introducing a new production method that uses cells of stacked wire mesh sheets that have a thick external shell deposited by cold spray. Fins are then machined in this external shell, creating a heat exchanger. Net shaped pin fins were successfully deposited using Cold Gas Dynamic Spraying (CGDS or simply cold spray) as an additive manufacturing technique to replace the plate fin arrays currently used. This new development is envisioned to save costs while providing higher heat transfer efficiency than traditional fin arrays. Increasing the performance of such fin arrays would yield higher heat exchanger efficiencies and increase the total efficiency of the gas turbine system. The present thesis provides a description of the research performed, as well as the results thereof, with regards to the performance of pin fin arrays produced using cold spray. A review of the relevant literature is performed to establish the motivation of this study and to describe the relevant work that has been performed by other authors in this respect. The research objectives are to evaluate the thermal and hydrodynamic performance of these fin arrays and relate those to the flow structures arising from fluid motion between these extended surfaces. Furthermore, the proposed approach and the experimental equipment that will be used are described in this work. The research objectives were successfully met, with the results obtained from this work presented in the form of peer-reviewed publications.

abstract: Honeycomb sandwich panels have been used in structural applications for several decades in various industries. While these panels are lightweight and rigid, their design has not evolved much due to constraints imposed by available manufacturing processes and remain primarily two-dimensional extrusions sandwiched between facings. With the growth in Additive Manufacturing, more complex geometries can now be produced, and advanced design techniques can be implemented into end use parts to obtain further reductions in weight, as well as enable greater multi-functionality. The question therefore is: how best to revisit the design of these honeycomb panels to obtain these benefits? In this work, a Bio-Inspired Design approach was taken to answer this question, primarily since the hexagonal lattice is so commonly found in wasp and bee nests, including the well-known bee’s honeycomb that inspired these panel designs to begin with. Whereas prior honeycomb panel design has primarily focused on the hexagonal shape of the unit cell, in this work we examine the relationship between the various parameters constituting the hexagonal cell itself, specifically the wall thickness and the corner radius, and also examine out-of-plane features that have not been previously translated into panel design. This work reports findings from a study of insect nests across 70 species using 2D and 3D measurements with optical microscopy and X-ray tomography, respectively. Data from these biological nests were used to identify design parameters of interest, which were then translated into design principles. These design principles were implemented in the design of honeycomb panels manufactured with the Selective Laser Sintering process and subjected to experimental testing to study their effects on the mechanical behavior of these panels. / Dissertation/Thesis / Masters Thesis Manufacturing Engineering 2020

Increased interest in and use of additive manufacturing has made it an important component of advanced manufacturing in the last decade. Material Extrusion Additive Manufacturing (MatEx) has seen a shift from a rapid prototyping method harnessed only in parts of industry due to machine costs, to something widely available and employed at the consumer level, for hobbyists and craftspeople, and industrial level, because falling machine costs have simplified investment decisions. At the same time MatEx systems have been scaled up in size from desktop scale Fused Filament Fabrication (FFF) systems to room scale Big Area Additive Manufacturing (BAAM). Today MatEx is still used for rapid prototyping, but it has also found application in molds for fiber layup processes up to the scale of wind turbine blades. Despite this expansion in interest and use, MatEx continues to be held back by poor part performance, relative to more traditional methods such as injection molding, and lack of reliability and user expertise. In this dissertation, a previously unreported phenomenon, irreversible thermal strain (ITε), is described and explored. Understanding ITε improves our understanding of MatEx and allows for tighter dimensional control of parts over time (each of which speaks to extant challenges in MatEx adoption). It was found that ITε occurs in multiple materials: ABS, an amorphous polymer, and PLA, a semi-crystalline one, suggesting a number of polymers may exhibit it. Control over ITε was achieved by tying its magnitude back to part layer thickness and its directionality to the direction of roads within parts. This was explained in a detail by a micromechanical model for MatEx described in this document. The model also allows for better description of stress-strain response in MatEx parts broadly. Expanding MatEx into new areas, one-way shape memory in a commodity thermoplastic, ABS, was shown. Thermal history of polymers heavily influences their performance and MatEx thermal histories are difficult to measure experimentally. To this end, a finite element model of heat transfer in the part during a MatEx build was developed and validated against experimental data for a simple geometry. The application of the model to more complex geometries was also shown. Print speed was predicted to have little impact on bonds within parts, consistent with work in the literature. Thermal diffusivity was also predicted to have a small impact, though larger than print speed. Comparisons of FFF and BAAM demonstrated that, while the processes are similar, the size scale difference changes how they respond to process parameter and material property changes, such as print speed or thermal diffusivity, with FFF having a larger response to thermal diffusivity and a smaller response to print speed. From this experimental and simulation work, understanding of MatEx has been improved. New applications have been shown and rational design of both MatEx processes and materials for MatEx has been enabled.