The Design Of A Robotic Arm Link Using Functionally Graded Materials: A Case Study

Functionally Graded Materials (FGMs) can outperform their homogeneous counterparts. Advances in digitalization technologies, mainly additive manufacturing, have enabled the synthesis of materials with tailored properties and functionalities. Joining dissimilar metals to attain compositional grading is a relatively unexplored research area and holds great promise for engineering applications. Metallurgical challenges may arise; thus, a theoretical critical analysis is presented in this paper. A multidisciplinary methodology is proposed here to unify optimal design, multi-feed Wire-Arc Additive Manufacturing (WAAM), and image-based characterization methods to create structure-specific oriented FGM parts. Topology optimization is used to design FGMs. A beam under pure bending is used to explore the layer-wise FGM concept, which is also analytically validated. The challenges, limitations, and role of WAAM in creating FGM parts are discussed, along with the importance of numerical validation using full-field deformation data. As a result, a conceptual FGM engineering workflow is proposed at this stage, enabling digital data conversion regarding geometry and compositional grading. This is a step forward in processing in silico data, with a view to experimentally producing parts in future. An optimized FGM beam, revealing an optimal layout and a property gradient from iron to copper along the build direction (bottom-up) that significantly reduces the normal pure bending stresses (by 26%), is used as a case study to validate the proposed digital workflow.

In recent years, additive manufacturing has been gaining ground among traditional manufacturing methods in many different applications. This is mainly due to its ease of prototyping, material savings and above all the highly complex geometries that can be achieved. Despite its many advantages, the use of additive manufacturing in electrical machines has been limited. The lack of maturity of the manufacturing processes and the increase in losses when applying additive approaches to some parts, mainly stators, have led little implementation in the field of electrical machines. The geometric freedom offered by additive manufacturing paves the way for the use of novel optimisation techniques, such as topology optimisation. Traditionally, topology optimisation has not been widely used because the complex geometries obtained by these algorithms are not easily produced by traditional manufacturing methods. However, thanks to additive manufacturing, topology optimisation has started to be used, mainly for mechanical applications and it has demonstrated its ability to reduce weight without compromising mechanical stability in several cases. Nevertheless, topology optimisation for physics other than mechanical has not been thoroughly studied, let alone for the simultaneous optimisation of different physics. In view of the scenario described, this thesis investigates the benefits that additive manufacturing and topology optimisation can bring to the design of electrical machines. For the additive manufacturing of electrical machines, a thorough literature review is carried out on the application of this manufacturing approach to different parts of electrical machines, active and non-active. Two main case studies are presented: in the first, the rotor, the shaft, the stator and the housing of an aerospace actuator are manufactured by L-PBF in FeCoV and the assembled actuator is tested. In the second case, a rotor is manufactured in FeSi by LP- DED. Finally, not considered an additive manufacturing case study itself in this thesis, but two electrical conductor prototypes are manufactured in CuCr1Zr and an additional geometry is manufactured in AlSi10Mg by L-PBF. With regard to topology optimisation of electrical machines, a description of the main topology optimisation methods used is given and their application to electrical machine components is presented. In a similar way to additive manufacturing, two case studies are analysed. First, a novel multiphysics - mechanical and electromagnetic - topology optimisation method is presented, in which the rotor and the stator of a permanent magnet motor are optimised simultaneously. This method is compared with two methods found in the literature, SIMP and on-off. Secondly, another topology optimisation method is described and applied to an electrical conductor model. The proposed algorithm involves a multiphysics - thermal and electromagnetic - hybrid parametric topology optimisation approach. Two reduced length geometries and one full length prototype are built via additive manufacturing. Finally, conclusions regarding additive manufacturing and topology optimisation of electrical machines are drawn from the work presented in this thesis. Future lines of work for additive manufacturing and topology optimisation of electrical machines are also presented.

Comparative study on life cycle assessment of components produced by additive and conventional manufacturing process

9 - Metal-ceramic functionally graded materials (FGMs)

Anthropogenic greenhouse gas emissions warming up the Earth’s atmosphere and triggering a climatic shift around the world evidence how the construction industry must provide a resilient built environment for an increasingly growing population, while at the same time reduce the use of cement and the demand for energy use from heating and cooling in an intensely urbanized world. Construction using Additive Manufacturing (AM) has gained traction in recent years, promising benefits such as: reduction in waste, building time, and need for formwork; customization and fabrication of complex geometries at no extra cost; and the reduction of human labor and on-site hazards. While most implementations of AM use cement as a primary material, development of alternative technologies that use earth-abundant, low-carbon renewable materials can be seen in projects such as Gaia by WASP, as well as efforts from the Institute for Advanced Architecture of Catalonia (IAAC). As a research framework, this project extends the efforts of building with renewable materials by developing a Functionally Graded Material (FGM) 3d Printing technology to create a bio-composite wall using lime, clay and hemp bast fiber. Unlike traditional, singular material deploying AM technologies, FGMs are a type of composite that use different materials according to where they are needed, with gradient transitioning between the materials to achieve non-discrete interphases. We work under the hypothesis that FGMs can achieve better strength-to-weight ratios than regular ceramics, and at the same time allow, through the 3d printing process, for an expression of the functional requirements of material change through form. While used in fields other than architecture, FGMs in AM have yet to be implemented in building construction.

Functionally graded materials and processing techniques: An art of review

Additive manufacturing of polymer-based functionally graded materials

Functionally graded materials (FGMs) are advanced materials that are used to prevent the problems that arise when composite materials with sharp interfaces are used in a harsh working environment, which includes stress singularities due to property mismatchs, poor adhesion, and delamination. A number of conventional manufacturing processes have been used to produce functionally graded materials and some of these manufacturing processes were presented in Chap. 3. Additive manufacturing (AM) technology is an advanced manufacturing process that offers many advantages and possibilities for the fabrication of complex three-dimensional products through material addition, as against the material removal in the conventional machining processes. Some of the AM technologies have the capability of fabricating complex parts that are made with the functionally graded material (FGM) in a single manufacturing process. Some of the AM technologies that are used to produce functional FGM parts include: selective-laser sintering, selective-laser melting, the laser-metal deposition process, and fused-deposition modelling. These AM technologies are presented in this chapter; and some of the research work using these technologies for the fabrication of FGMs are also reviewed.

Directed energy deposition (DED) stands as a key process in metal additive manufacturing (AM) and offers the unique capability of creating functionally graded materials (FGMs). FGMs have garnered significant interest in high-value industries by advantages such as performance optimization, reducing material defects, and resolving joining issues. However, post-processing remains a crucial step, indicating a need for further research to understand the machinability of FGMs. This paper focuses on the characteristics analysis of fabricating and machining an FGM based on stainless steel 316L (SAE 316L) and Inconel 718. The FGM was fabricated by starting with SAE 316L at 100 wt.% and adjusting the composition ratio by incrementally increasing Inconel 718 by 20 wt.% while simultaneously decreasing SAE 316L. Following the FGM fabrication, microstructure and mechanical properties were comprehensively analyzed by hardness testing, optical microstructure measurements, energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD). To investigate the post-processing aspects, end-milling experiments were conducted using two distinct milling methods (upward and downward milling) and machining paths (from SAE 316L towards Inconel 718, and vice versa). The mean cutting force peaked at 148.4 N in upward milling and dipped to 70.5 N in downward milling, and tool wear measurements further provided insights into the optimal milling direction when working with an FGM of SAE 316L and Inconel 718.

Additive manufacturing evolution in construction: From individual terrestrial to collective, aerial, and extraterrestrial applications

Professor Akinlabi’s research and her team has focused on the field of advanced and modern manufacturing processes like Laser Additive Manufacturing (AM), in particular laser material processing. Her other research work is focused on laser metal deposition and functionally graded materials of titanium-based alloys and other materials. Some of the studies she has been involved in focus on cladding titanium with titanium carbide for enhanced wear properties, the cladding of titanium alloy biological implants with hydroxyapatite (HAP) for improved osteo-integration, and the cladding of Grade 5 titanium alloy with copper for improved corrosion properties for marine applications. Akinlabi focuses her investigations on the development of advanced metallic coatings on Ti-6Al-4V substrate using additive manufacturing technology for improved surface performance; with targeted applications in the aerospace, automotive, and shipbuilding industries. This work makes a substantial contribution to knowledge by bringing the theoretical clarity and experimental studies required for the effective assessment of surface degradation mechanisms in additive manufactured Ti-6Al-4V alloy. This is ascribed to the elimination of high residual stresses and crack formation through the optimization of laser processing parameters, leading to enhanced quality of the coatings, surface adhesion between the substrate and the reinforcement materials, microstructural evolution and thus improved mechanical properties. Her research was developed to produce advanced innovative corrosion-wear resistant coatings with enhanced hardness, tribological property, and sustainable anti-corrosion performance thereby, consequently lengthening the lifespan and durability of titanium and its alloys, eliminating material loss and equipment damage, minimizing cost of maintenance, and reduced failure of this material. Despite all the benefits derived from AM technology, there are still a lot of unresolved issues with the technology that has hindered its performance and commercialisation thereby limiting its application to high tolerant utilizations. Professor Akinlabi research on additive manufacturing techniques had produced near-net-shape, light weight and high strength components which has gradually revolutionized the manufacturing sector. The use of the technology is now providing sustainable production benefits, as ability to repair and manufacture components can now be employed to increase product life circle. Against this background, the Additive Manufacturing technology is in itself referred to as a technology of the future despite its versatile applications in the industry. On the other hand, Functionally Graded Materials (FGMs) are advanced materials usually developed for specific and tailored applications. The FGMs also referred to as materials of the future as its applications are not yet fully explored for tailored applications. In this talk, Prof Akinlabi shared some of her research endeavours in the field of AM and FGMs, and also shared the scope on the primary objectives of the joint project which was to be undertaken on FGM of Titanium alloy and Titanium Carbide.

Additive manufacturing (AM) has enabled the fabrication of functionally graded materials (FGM) with tailored properties for advanced applications in marine, aerospace and automotive sectors. In the present study, SS304/SS347 functionally graded walls were fabricated using gas metal arc welding (GMAW)-based AM and their mechanical and microstructural characteristics were systematically investigated. The fabricated FGM walls exhibited enhanced tensile performance, achieving a 1.06% improvement in ultimate tensile strength compared to SS347. Microstructural analysis revealed coarsened dendritic morphologies and the presence of residual ferrite, which are attributed to the complex thermal history experienced during layer-by-layer deposition. Finite element analysis was employed to predict the mechanical response, and the numerical results showed good agreement with experimental observations, with minimal deviation. The outcomes of this study demonstrate the capability of GMAW-based AM to produce high-performance FGM and emphasize the critical role of thermal history in governing microstructure–property relationships, thereby supporting the effective design and optimization of FGM for advanced engineering application.

A state-of-art review on functionally graded materials (FGMs) manufactured by 3D printing techniques: Advantages, existing challenges, and future scope

Topology optimization is an optimization method that employs mathematical tools to optimize material distribution in a part to be designed. Earlier developments of topology optimization considered conventional manufacturing techniques that have limitations in producing complex geometries. This has hindered the topology optimization efforts not to fully be realized. With the emergence of additive manufacturing (AM) technologies, the technology that builds a part layer upon a layer directly from three dimensional (3D) model data of the part, however, producing complex shape geometry is no longer an issue. Realization of topology optimization through AM provides full design freedom for the design engineers. The article focuses on topologically optimized design approach for additive manufacturing with a case study on lightweight design of jet engine bracket. The study result shows that topology optimization is a powerful design technique to reduce the weight of a product while maintaining the design requirements if additive manufacturing is considered.

Analysis of formation and growth of the σ phase in additively manufactured functionally graded materials