The term photonic crystals appears because of the analogy between electron waves in crystals and the light waves in artificial periodic dielectric structures. During the recent years the investigation of one-, two-and three-dimensional periodic structures has attracted a widespread attention of the world optics community because of great potentiality of such structures in advanced applied optical fields. The interest in periodic structures has been stimulated by the fast development of semiconductor technology that now allows the fabrication of artificial structures, whose period is comparable with the wavelength of light in the visible and infrared ranges.

http://ieeexplore.ieee.org/iel5/6354/16969/00781867.pdf

Photonic crystals

The use of 3D printing for rapid tooling and manufacturing has promised to produce components with complex geometries according to computer designs. Due to the intrinsically limited mechanical properties and functionalities of printed pure polymer parts, there is a critical need to develop printable polymer composites with high performance. 3D printing offers many advantages in the fabrication of composites, including high precision, cost effective and customized geometry. This article gives an overview on 3D printing techniques of polymer composite materials and the properties and performance of 3D printed composite parts as well as their potential applications in the fields of biomedical, electronics and aerospace engineering. Common 3D printing techniques such as fused deposition modeling, selective laser sintering, inkjet 3D printing, stereolithography, and 3D plotting are introduced. The formation methodology and the performance of particle-, fiber- and nanomaterial-reinforced polymer composites are emphasized. Finally, important limitations are identified to motivate the future research of 3D printing.

3D printing of polymer matrix composites: A review and prospective

The past few decades have seen substantial growth in Additive Manufacturing (AM) technologies. However, this growth has mainly been process-driven. The evolution of engineering design to take advantage of the possibilities afforded by AM and to manage the constraints associated with the technology has lagged behind. This paper presents the major opportunities, constraints, and economic considerations for Design for Additive Manufacturing. It explores issues related to design and redesign for direct and indirect AM production. It also highlights key industrial applications, outlines future challenges, and identifies promising directions for research and the exploitation of AM's full potential in industry.

/pdf/design-for-additive-manufacturing-trends-opportunities-22heccleea.pdf

Design for additive manufacturing: trends, opportunities, considerations, and constraints

Design for manufacture and assembly (DFM) has typically meant that designers should tailor their designs to eliminate manufacturing difficulties and minimize manufacturing, assembly, and logistics costs. However, the capabilities of additive manufacturing technologies provide an opportunity to rethink DFM to take advantage of the unique capabilities of these technologies. As mentioned in Chap. 16, several companies are now using AM technologies for production manufacturing. For example, Siemens, Phonak, Widex, and the other hearing aid manufacturers use selective laser sintering and stereolithography machines to produce hearing aid shells; Align Technology uses stereolithography to fabricate molds for producing clear dental braces (“aligners”); and Boeing and its suppliers use polymer powder bed fusion (PBF) to produce ducts and similar parts for F-17 fighter jets. For hearing aids and dental aligners, AM machines enable manufacturing of tens to hundreds of thousands of parts, where each part is uniquely customized based upon person-specific geometric data. In the case of aircraft components, AM technology enables low-volume manufacturing, easy integration of design changes and, at least as importantly, piece part reductions to greatly simplify product assembly.

Design for Additive Manufacturing

A comprehensive analysis of literature pertaining to surface texture metrology for metal additive manufacturing has been performed. This review paper structures the results of this analysis into sections that address specific areas of interest: industrial domain; additive manufacturing processes and materials; types of surface investigated; surface measurement technology and surface texture characterisation. Each section reports on how frequently specific techniques, processes or materials have been utilised and discusses how and why they are employed. Based on these results, possible optimisation of methods and reporting is suggested and the areas that may have significant potential for future research are highlighted.

Surface texture metrology for metal additive manufacturing: a review

3D printing is an emerging technology in manufacturing. It is the long-term goal of the industry to print complex and fully functional products from cell phones to vehicles. A drawback of many 3D printing technologies is rough surface finish. It is known that metals with high surface roughness severely degrade the propagation of electromagnetic waves. Presented is the first known evaluation of the electromagnetic impact of the typical surface roughness in metal parts produced by electron beam melting. Two Ku-band (12-15 GHz) horn antennas were 3D printed, with different surface roughness, and compared to a standard horn antenna purchased from Pasternack.

https://ietresearch.onlinelibrary.wiley.com/doi/pdf/10.1049/el.2013.1528

Effects of extreme surface roughness on 3D printed horn antenna

Material properties in radio frequency and microwave regimes are limited due to the lack of molecular resonances at these frequencies. Metamaterials are an attractive means to realize a prescribed permittivity or permeability function, but these are often prohibitively lossy due to the use of ine-cient metallic resonators. All-dielectric metamaterials ofier excellent potential to overcome these losses, but they provide a much weaker interaction with an applied wave. Much design freedom can be realized from all-dielectric structures if their dispersion and anisotropy are cleverly engineered. This, however, leads to structures with very complex geometries that cannot be manufactured by conventional techniques. In this work, artiflcially anisotropic metamaterials are designed and then manufactured by 3D printing. The efiective material properties are measured in the lab and agree well with model predictions.

https://www.jpier.org/pierl/pierl34/08.12070311.pdf

3D printing of anisotropic metamaterials

Wireless passive temperature sensors are receiving increasing attention due to the ever-growing need of improving energy efficient and precise monitoring of temperature in high-temperature energy conversion systems, such as gas turbines and coal-based power plants. Unfortunately, the harsh environment, such as high temperature and corrosive atmosphere present in these systems, has significantly limited the reliability and increased the costs of current solutions. Therefore, this paper presents the concept and design of a low cost, passive, and wireless temperature sensor that can withstand high temperature and harsh environments. The temperature sensor was designed following the principle of metamaterials by utilizing closed ring resonators in a dielectric ceramic matrix. The proposed wireless, passive temperature sensor behaves like an $LC$ circuit, which has a temperature-dependent resonance frequency. Full-wave electromagnetic solver Ansys Ansoft HFSS was used to validate the model and evaluate the effect of different geometry and combination of split ring resonator structures on the sensitivity and electrical sizes of the proposed sensor. The results demonstrate the feasibility of the sensor and provide guidance for future fabrication and testing.

Concept and Model of a Metamaterial-Based Passive Wireless Temperature Sensor for Harsh Environment Applications

In this work, results are given for controlling waves arbitrarily inside a lattice with spatially variant self-collimation. To demonstrate the concept, an unguided beam was made to flow around a 90◦ bend without scattering due to the bend or the spatial variance. Control of the field was achieved by spatially varying the orientation of the unit cells throughout a self-collimating photonic crystal, but in a manner that almost completely eliminated deformations to the size and shape of the unit cells. The device was all-dielectric, monolithic, and made from an ordinary dielectric with low relative permittivity (er = 2.45). It was manufactured by fused deposition modeling, a form of 3D printing, and its performance confirmed experimentally at around 15 GHz.

/pdf/3d-printed-lattices-with-spatially-variant-self-collimation-l6i0p5bga4.pdf

3D Printed Lattices with Spatially Variant Self-Collimation

In this paper, an all-dielectric frequency selective surface (ADFSS) was developed using genetic algorithms and fast Fourier transforms (FFTs) to generate random geometries. This device showed a stop-band fractional bandwidth (FBW) of 54% and a field of view of 16°. The optimized FSS was manufactured by three-dimensional (3-D) printing and the frequency response was measured in the laboratory. This device was also tested in the pass band at a high pulsed microwave power of $\bf{45.26}\;\bf{MW}/\bf{m}^{\bf{2}}$ and no damage was observed. This is the first known demonstration of a 3-D printed ADFSS.

Cesar R. Garcia

Papers

Effects of extreme surface roughness on 3D printed horn antenna

3D printing of anisotropic metamaterials

Concept and Model of a Metamaterial-Based Passive Wireless Temperature Sensor for Harsh Environment Applications

3D Printed Lattices with Spatially Variant Self-Collimation

3-D Printed All-Dielectric Frequency Selective Surface With Large Bandwidth and Field of View