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

Additive manufacturing (AM) alias 3D printing translates computer-aided design (CAD) virtual 3D models into physical objects. By digital slicing of CAD, 3D scan, or tomography data, AM builds objects layer by layer without the need for molds or machining. AM enables decentralized fabrication of customized objects on demand by exploiting digital information storage and retrieval via the Internet. The ongoing transition from rapid prototyping to rapid manufacturing prompts new challenges for mechanical engineers and materials scientists alike. Because polymers are by far the most utilized class of materials for AM, this Review focuses on polymer processing and the development of polymers and advanced polymer systems specifically for AM. AM techniques covered include vat photopolymerization (stereolithography), powder bed fusion (SLS), material and binder jetting (inkjet and aerosol 3D printing), sheet lamination (LOM), extrusion (FDM, 3D dispensing, 3D fiber deposition, and 3D plotting), and 3D bioprinting....

Polymers for 3D Printing and Customized Additive Manufacturing

In the laser treatment of a workpiece (9), e.g. for surface hardening, melting, alloying, cladding, welding or cutting, the adverse effect of reflectivity of the surface, when a pure, monochromatic laser (6) is used, is remedied by the simultaneous application of a relatively shorter wavelength beam (1). The two beams (1)(5) may be combined by a beam coupler (4) or may reach the workpiece (9) by separate optical paths (not shown). The shorter wavelength beam (1) improves the coupling efficiency of the higher- powered laser beam (5).

Laser Material Processing

This paper describes a combined fabrication method for creating a bi-material micro-scale coating on fiber Bragg grating (FBG) optical sensors using laser-assisted maskless microdeposition (LAMM) and electroless nickel plating. This bi-material coating alters the sensitivity of the sensor where it also acts as a protective layer. LAMM is used to coat bare FBGs with a 1–2 µm thick conductive silver layer followed by the electroless nickel plating process to increase layer thickness to a desired level ranging from 1 to 80 µm. To identify an optimum coating thickness and predict its effect on the sensor's sensitivity to force and temperature, an optomechanical model is developed in this study. According to the model if the thickness of the Ni layer is 30–50 µm, maximum temperature sensitivity is achieved. Our analytical and experimental results suggest that the temperature sensitivity of the coated FBG with 1 µm Ag and 33 µm Ni is almost doubled compared to a bare FBG with sensitivity of 0.011 ± 0.001 nm °C−1. In contrast, the force sensitivity is decreased; however, this sensitivity reduction is less than the values reported in the literature.

http://www.aoms-tech.com/Library/Publications/2.pdf

Sensitivity alteration of fiber Bragg grating sensors with additive micro-scale bi-material coatings

Chemical modification of titanium immersed in hydrogen peroxide using nanosecond pulsed fiber laser irradiation

A mathematical model of laser directed energy deposition for process mapping and geometry prediction of Ti-5553 single-tracks

Laser-assisted maskless microdeposition of silver nano-particles on a magnesium substrate

The rapid additive manufacturing (AM) of highly viscous elastomers such as silicone has recently become possible due to the advancements in the fluid dispensing mechanism of material jetting systems leading to jetting of inks with a viscosity of 106 mPa.s under the shear stress of the nozzle. The drop-on-demand material delivery, which is the key to rapid AM of silicone prepolymers in these systems, can be the source of an inferior mechanical performance of AM-made parts compared to the bulk material because of their increased level of porosity as a result of jet printing. In this paper, the rheological properties of silicone have been tuned to maximize the density of AM-made silicone parts (99.6%) and reduce the difference between the mechanical properties of AM-made and cast parts. Parts that were printed and molded using the optimized ink demonstrate statistically insignificant differences between their ultimate tensile strength and strain, tearing resistance, and hardness.

Ehsan Toyserkani

Papers

Sensitivity alteration of fiber Bragg grating sensors with additive micro-scale bi-material coatings

Chemical modification of titanium immersed in hydrogen peroxide using nanosecond pulsed fiber laser irradiation

A mathematical model of laser directed energy deposition for process mapping and geometry prediction of Ti-5553 single-tracks

Laser-assisted maskless microdeposition of silver nano-particles on a magnesium substrate

High-speed material jetting additive manufacturing of silicone structures: mechanical characterization