There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Additive manufacturing of metallic components – Process, structure and properties

Freedom of design, mass customisation, waste minimisation and the ability to manufacture complex structures, as well as fast prototyping, are the main benefits of additive manufacturing (AM) or 3D printing. A comprehensive review of the main 3D printing methods, materials and their development in trending applications was carried out. In particular, the revolutionary applications of AM in biomedical, aerospace, buildings and protective structures were discussed. The current state of materials development, including metal alloys, polymer composites, ceramics and concrete, was presented. In addition, this paper discussed the main processing challenges with void formation, anisotropic behaviour, the limitation of computer design and layer-by-layer appearance. Overall, this paper gives an overview of 3D printing, including a survey on its benefits and drawbacks as a benchmark for future research and development.

Additive manufacturing (3D printing): A review of materials, methods, applications and challenges

This paper reviews the state-of-the-art of an important, rapidly emerging, manufacturing technology that is alternatively called additive manufacturing (AM), direct digital manufacturing, free form fabrication, or 3D printing, etc. A broad contextual overview of metallic AM is provided. AM has the potential to revolutionize the global parts manufacturing and logistics landscape. It enables distributed manufacturing and the productions of parts-on-demand while offering the potential to reduce cost, energy consumption, and carbon footprint. This paper explores the material science, processes, and business consideration associated with achieving these performance gains. It is concluded that a paradigm shift is required in order to fully exploit AM potential.

/pdf/metal-additive-manufacturing-a-review-lwo0wxslqj.pdf

Metal Additive Manufacturing: A Review

Natural structural materials are built at ambient temperature from a fairly limited selection of components. They usually comprise hard and soft phases arranged in complex hierarchical architectures, with characteristic dimensions spanning from the nanoscale to the macroscale. The resulting materials are lightweight and often display unique combinations of strength and toughness, but have proven difficult to mimic synthetically. Here, we review the common design motifs of a range of natural structural materials, and discuss the difficulties associated with the design and fabrication of synthetic structures that mimic the structural and mechanical characteristics of their natural counterparts.

Bioinspired structural materials

Additive Manufacturing of Metals: The Technology, Materials, Design and Production

A general approach for using infinite elements within the context of the finite element method is presented. Based upon Gauss-Laguerre quadrature, a scheme for numerically computing the infinite element characteristic matrices is proposed. The general formulation of the element shape functions is outlined, including that for infinite elements that model the far field of hyperbolic systems. The technique is illustrated with a classical example in elasticity: a vertically loaded circular rigid plate.

Finite element techniques for problems of unbounded domains

The present invention provides a system and method for making a three-dimensional electronic, electromagnetic or electromechanical component/device by: (1) creating one or more layers of a three-dimensional substrate by depositing a substrate material in a layer-by- layer fashion, wherein the substrate includes a plurality of interconnection cavities and component cavities; (2) filling the interconnection cavities with a conductive material; and (3) placing one or more components in the component cavities.

Extrusion-based additive manufacturing system for 3d structural electronic, electromagnetic and electromechanical components/devices

Amplification of evanescent electromagnetic waves by a metamaterial slab is still a controversial issue. Metallic waveguides operating in cutoff provide a unique physical environment to produce and study these waves because isolated evanescent modes can be excited in such environment. In this paper, the tunneling of electromagnetic waves through a rectangular waveguide partially filled by a metamaterial is analyzed. Enhanced tunneling due to the amplification of evanescent waves in the metamaterial filled waveguide section is demonstrated. Since evanescent modes in rectangular waveguides are the superposition of two plane waves, the aforementioned results also show the amplification and tunneling of evanescent plane waves by a metamaterial slab in free space.

/pdf/near-perfect-tunneling-and-amplification-of-evanescent-9mkyjs7iq9.pdf

Near-perfect tunneling and amplification of evanescent electromagnetic waves in a waveguide filled by a metamaterial: Theory and experiments

A novel design for 2D isotropic left-handed metamaterials is presented. One of the main advantages of our proposal is that all the metallizations are placed at parallel stratified planes. Thus, this design can be realized by means of the well known, commonly used planar technology. An analytical model is provided for the analysis of this new metamaterial. Numerical results obtained by using this model are validated by experimental simulations. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 405–408, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10620

Francisco Medina

Papers

Additive Manufacturing of Metals: The Technology, Materials, Design and Production

Finite element techniques for problems of unbounded domains

Extrusion-based additive manufacturing system for 3d structural electronic, electromagnetic and electromechanical components/devices

Near-perfect tunneling and amplification of evanescent electromagnetic waves in a waveguide filled by a metamaterial: Theory and experiments

A new 2D isotropic left‐handed metamaterial design: Theory and experiment