As the application of additive manufacturing (AM) reaches an unprecedented scale in both academia and industry, a reflection upon the state-of-the-art developments in the design for additive ...manufacturing (DfAM) and structural optimisation, becomes vital for successfully shaping the future AM-landscape. A framework, highlighting both the interdependencies between these two central aspects in AM and the necessity for a holistic approach to structural optimization, using lightweight strategies such as topology optimization and/or latticing, was established to summarize the reviewed content. Primarily focusing on isotropic material considerations and basic stiffness-optimal problems, these concepts have already found wide application, bridging the gaps between design and manufacturing as well as academia and industry. In pursuit of streamlining the AM-workflow towards digitally print-ready designs, studies are increasingly investigating mathematically-based structural optimization approaches in conjunction with DfAM-specific constraints, providing a portfolio of solutions like generative design, which is gaining traction in industry. Besides an overview on economically-driven to performance-driven design optimizations, insight into commercial AM-specific software is provided, elucidating potentials and challenges for the community. Despite the abundance of AM design methods to-date, computationally inexpensive solutions for common engineering problems are still scarce, which is constituting one of many key challenges for the future.
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•Extensive review, providing a joint perspective on design and structural optimisation in additive manufacturing (AM).•Overview on the lightweighting approaches topology optimization and latticing, considering isotropic material assumptions.•Consolidated summary, elucidating the gaps between design and manufacturing as well as academia and industry.•Establishment of a design for AM framework, highlighting the interdependencies between state-of-the art research topics.•Identification of future trajectories beneficial to explore in pursuit of exploiting the potential AM has on offer.
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•Hybrid additive manufacturing (AM) is re-defined through physical mechanisms.•Innovation via “property-mechanism-energy source-hybrid-AM process (PMEH)” system.•Data compiled from ...100 papers will be available to the community.•Data includes material/part properties, PMEH categories, and paper information.
This study defined hybrid additive manufacturing (AM) as “in-situ or series combination of an additive manufacturing process and secondary energy sources in which physical mechanisms are fundamentally altered/controlled to affect the resulting properties of material and/or part.” This definition includes in-situ secondary processes as well as process chains, and it is anchored in multi-physical mechanisms such that new hybrid-AM processes can be freely and systematically sought or invented through a systems approach epitomized by the “property – mechanism – energy source – hybrid-AM process (PMEH)” thought process. The sequence of driving forces in this framework are as such: desired material properties determine which mechanism is utilized and, in turn, the energy source to be applied, which ultimately defines the hybrid-AM process. The five unifying physical mechanisms that were identified in this study are: melt pool dynamics, microstructure development, stress state, surface evolution, and thermal gradients. Analysis of properties, mechanisms, energy sources, and processes was conducted on more than 100 papers, and the results ultimately show the effect of mechanisms on material properties. Mechanisms are further classified by energy source, which are in turn broken down by hybrid-AM process. Additionally, each mechanism was defined and reviewed in detail, highlighting the PMEH relationship for metal hybrid-AM materials. Further analysis compares reported mechanical property values for hybrid-AM processes to both AM only and wrought properties for 316 L, Alloy 718, and Titanium Gr 5. Finally, future directions of research as well as clear gaps in knowledge are identified, which includes lack of variety in utilized energy sources, lack of material diversity, process chain integration and improvement, and promising hybrid-AM processes. With the presented analysis and PMEH framework, it is determined that metal AM hybrid processes are well suited to address current problems and show promise in creating superior and versatile materials. Further growth in this field is expected to be exponential, and the developed PMEH framework will aid in framing these innovative processes.
This open access book gives both a theoretical and practical overview of several important aspects of additive manufacturing (AM). It is written in an educative style to enable the reader to ...understand and apply the material. It begins with an introduction to AM technologies and the general workflow, as well as an overview of the current standards within AM. In the following chapter, a more in-depth description is given of design optimization and simulation for AM in polymers and metals, including practical guidelines for topology optimization and the use of lattice structures. Special attention is also given to the economics of AM and when the technology offers a benefit compared to conventional manufacturing processes. This is followed by a chapter with practical insights into how AM materials and processing parameters are developed for both material extrusion and powder bed fusion. The final chapter describes functionally graded AM in various materials and technologies. Throughout the book, a large number of industrial applications are described to exemplify the benefits of AM.
Wire and Arc Additive Manufacturing (WAAM) is a metal 3D printing technique based on robotic welding. This technique yields potential in decreasing material consumption due to its high material ...efficiency and freedom of shape. Empirical measurements of WAAM, using a deposition rate of 1 kg/h, were performed on site of MX3D. The measured power consumption per kg stainless steel is 2.72 kW, of which 1.74 is consumed by the welder, 0.44 by the robotic arm, and 0.54 by the ventilation. The material loss was 1.1%. A 98% argon 2% CO2 welding gas was used with a flow of 12 l/min.
A cradle-to-gate Life Cycle Assessment (LCA) was performed. To give this assessment context, green sand casting and CNC milling were additionally assessed, through literature and databases. The purpose of this study is to develop insight into the environmental impact of WAAM. Results indicate that, in terms of total ReCiPe endpoints, the environmental impact of producing a kg of stainless steel 308 l product using WAAM is comparable to green sand casting. It equals CNC milling with a material utilization fraction of 0.75. Stainless steel is the main cause of environmental damage in all three techniques, emphasizing the importance of WAAM's mass reduction potential. When environmentally comparing the three techniques for fulfilling a certain function, optimized designs should be introduced for each manufacturing technique. Results can vary significantly based on product shape, function, materials, and process settings.
Rapid advancements in science and technology have assured biomaterials and their associated fields towards becoming a multimillion-dollar industry. Biomaterials have been shown as one of the most ...promising materials for biomedical implant development. As such, this article intends to provide a comprehensive review of metal additive manufacturing (metal-AM) processes evolution used in biomedical applications. The most common types of metal-AM methods practised today are Selective Laser Sintering (SLS), Selective Laser Melting (SLM), Direct Metal Laser Sintering (DMLS), Electron Beam Melting (EBM) and Laser Engineered Net Shaping (LENS). The present review also covers the application of these metal-AM systems in Ti-6Al-4V-based implants fabrication. The scientific challenges and critical issues towards improving the biomaterial properties so that they are more notable in the biomedical industry are also discussed.
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Polymeric composites with multi-functionality offer significant advantages over metals, including lightweight, high strength and stiffness, corrosion and fatigue resistance, etc. Additively ...manufactured composites draw intensive attention over the past decade due to that they exhibit the large potential to extend their applications from rapid prototyping to functional end-use components. Moreover, advances in additive manufacturing (AM) open new perspectives for the next generation of design and manufacturing of composites, which possess spatially digitalized and materialized arrangement of material/structure in a voxel-by-voxel manner. This review examines the work performed in this fast-growing field and elaborates its future perspectives and potentials. Specifically, the polymer AM processes incorporating different types of reinforcements are discussed in terms of mechanism, feedstocks, their advantages, and constraints. Then, the AM-driven designs for polymeric composites on multiscale and for multi-functional applications are emphasized. Further, emerging research topics including digital composites, intelligence/data-driven design approaches, and four-dimensional printing are further addressed with the careful analysis of existing gaps and future research trends. Finally, this review is concluded with an outlook on future research opportunities on AM-fabricated composites from design to fabrication. This review aims to provide a comprehensive guide to the stakeholders who want to utilize or develop an AM process for polymeric composites.
•An analytical model was established and analyzed for the first time.•The design was verified with experiments and finite element analysis.•The tailorability of mechanical properties was demonstrated ...for the structure.•Manufacturing induced mechanical property issues were discussed.
In this work, an analytical model of a 3D re-entrant honeycomb auxetic cellular structure has been established based on both a large deflection beam model and a Timoshenko beam model. Analytical solutions for the modulus, Poisson’s ratios and yield strength of the cellular structure in all principal directions were obtained, which indicate a wide range of mechanical property control via geometrical designs. The results were compared with experimentation and finite element analysis, and it was verified that the analytical model provides a convenient and relatively accurate method in the prediction of the performance for the auxetic cellular structures once the manufacturing related factors are adequately incorporated into the model. It was also found that the model provides less accurate predictions when higher-order coupling effects such as warp locking becomes significant under lower structural symmetry.
Additive manufacturing (AM), also known as 3D printing or rapid prototyping, is gaining increasing attention due to its ability to produce parts with added functionality and increased complexities in ...geometrical design, on top of the fact that it is theoretically possible to produce any shape without limitations. However, most of the research on additive manufacturing techniques are focused on the development of materials/process parameters/products design with different additive manufacturing processes such as selective laser melting, electron beam melting, or binder jetting. However, we do not have any guidelines that discuss the selection of the most suitable additive manufacturing process, depending on the material to be processed, the complexity of the parts to be produced, or the design considerations. Considering the very fact that no reports deal with this process selection, the present manuscript aims to discuss the different selection criteria that are to be considered, in order to select the best AM process (binder jetting/selective laser melting/electron beam melting) for fabricating a specific component with a defined set of material properties.
Additive manufacturing (AM) offers unprecedented design freedom and manufacturing flexibility for processing complex components. Despite the numerous advantages of AM over conventional manufacturing ...methods, there are still some issues and bottlenecks that hinder the wide-scale industrial adaptation of AM techniques. The emerging field-assisted additive manufacturing (FAAM) is a designation that combines different auxiliary energy fields (e.g., ultrasound, magnetism, etc.) to overcome limitations in AM by benefiting from the intrinsic advantages of auxiliary fields. This work provides an up-to-date and dedicated review of FAAM in metallic materials, assisted by mainstream auxiliary magnetic, acoustic, mechanical, and thermal fields, as well as some emerging fields. The work principle and interaction mechanism between the field and the deposited metallic materials are elucidated. FAAM processes simulation and modelling are also reviewed. The auxiliary fields can affect the melt pool convection and dynamics, alter the temperature profile and thermal history during material solidification and induce stress or plastic deformation to the deposited materials. Hence, the effects of the auxiliary fields on the melt pool dynamics, solidification kinetics, densification behaviour, microstructure and texture, mechanical properties and fatigue performance are reviewed and discussed in detail. The perspectives on the research gap and further development trends of FAAM are also discussed.
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•Advancements in field-assisted additive manufacturing (FAAM) are elucidated.•Interaction mechanisms between field and deposited metallic materials are revealed.•Correlations among auxiliary field, microstructure and mechanical properties are summarized.•Perspectives on research opportunities in field-assisted additive manufacturing are outlooked.
This paper discusses the effects of process parameters in TIG based WAAM for specimens created using Hastelloy X alloy (Haynes International) welding wire and 304 stainless-steel plate as the ...substrate. The Taguchi method and ANOVA were used to determine the effects of travel speed, wire feed rate, current, and argon flow rate on the responses including bead shape and size, bead roughness, oxidation levels, melt through depth, and the microstructure. Travel speed and current were found to have the largest effect on the responses. Increasing travel speed or decreasing current caused a decrease in melt through depth and an increase in roughness. Printing strategies were tested using specimens of multiple layers and no significant difference was found between printing layers in the same direction and printing layers in alternating directions. No observable interface between the layers was present suggesting a complete fusion between layers with no oxidation. Three distinct zones were identified within the three- and eight-layer samples. The zones were characterized by the size and distribution of the molybdenum carbide formations within the matrix grain formations.
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