Additive manufacturing (AM) is transforming all segments of the aerospace industry, including commercial and military aircraft, space applications, as well as missiles systems. Such transformation is due to the unique ability of AM to produce parts with complex designs, reduce manufacturing costs (material waste, assembly due to part consolidation, and the need for tools and fixtures), and fabricate parts with premium materials with small production runs and short turnaround times. AM allows the realization of advanced part designs that provide additional space, multifunctional parts, multimaterial parts, part consolidation, and parts that are difficult to machine. The capability of AM to fabricate freeform designs makes it very suitable for the aerospace industry. To date, aerospace companies, such as Boeing, have installed tens of thousands AM parts (including 200 unique nonmetallic part references) on 16 commercial and military aircraft. It has also started the production of titanium AM parts that will allow savings of up to three million USD per aircraft in the near future. GE Aviation is using metal AM to manufacture thousands of fuel nozzles annually for its new LEAP engine. Similarly, Airbus is utilizing metal AM brackets and bleed pipes on its aircraft. It is currently collaborating with Arconic on the production of large-scale AM airframe components and expects to produce 30 t of AM metal parts by December 2018. The main applications of AM in the aerospace industry are rapid prototyping, rapid tooling, and repair, as well as direct digital manufacturing (DDM) of parts made of metal, plastic, ceramic, and composite materials. Currently, the fastest growing application is DDM (final part manufacturing). For metal parts, the main AM technologies in aerospace applications are directed energy deposition and powder bed fusion. For nonmetallic parts, the dominant AM technologies are vat photopolymerization, material jetting, and material extrusion. This chapter reviews the applications, benefits, and opportunities of AM for the aerospace industry, describes the relevant AM technologies, and discusses the current challenges and potential applications.

Review of additive manufacturing technologies and applications in the aerospace industry

Fused Deposition Modeling (FDM) is a widely used additive manufacturing technology for fabrication of complex geometric parts using thermoplastic polymers. The quality issues and inferior properties of fabricated parts limited this process to manufacture parts for industrial level applications. Reinforcing the polymer with nanoparticles, short fibers or continuous fibers improve mechanical, thermal and electrical properties compared to the neat polymer. Several works have been carried out since last two decades to print quality products through FDM by using composite materials. The success of expanding this technique to industrial applications depends on the preparation of printable composite feedstock filament and printing without defects. This article reviews the challenges involved in the preparation of composite feedstock filaments and printing issues during the printing of nano composites, short and continuous fiber composites. The printing process of various thermoplastic composites ranging from amorphous to crystalline polymers is discussed. Also, detailed explanation is given about the analytical and numerical models used for simulating the FDM printing process and for estimating the mechanical properties of the printed parts. This critical review mainly helps the young researchers working in the area of processing of composite materials via 3D printing.

A critical review on the fused deposition modeling of thermoplastic polymer composites

Breakthrough in the printing tactics for stimuli-responsive materials: 4D printing

Exploring the potential of additive manufacturing for product design in a circular economy

The combination of materials with targeted optical properties and of complex, 3D architectures, which can be nowadays obtained by additive manufacturing, opens unprecedented opportunities for developing new integrated systems in photonics and optoelectronics The recent progress in additive technologies for processing optical materials is here presented, with emphasis on accessible geometries, achievable spatial resolution, and requirements for printable optical materials Relevant examples of photonic and optoelectronic devices fabricated by 3D printing are shown, which include light-emitting diodes, lasers, waveguides, optical sensors, photonic crystals and metamaterials, and micro-optical components The potential of additive manufacturing applied to photonics and optoelectronics is enormous, and the field is still in its infancy Future directions for research include the development of fully printable optical and architected materials, of effective and versatile platforms for multimaterial processing, and of high-throughput 3D printing technologies that can concomitantly reach high resolution and large working volumes

https://onlinelibrary.wiley.com/doi/pdf/10.1002/adom.201800419

Additive Manufacturing: Applications and Directions in Photonics and Optoelectronics.

Additive Manufacturing (AM) is a game changing production technology for aerospace applications. Fused deposition modeling is one of the most widely used AM technologies and recently has gained much attention in the advancement of many products. This paper introduces an extensive review of fused deposition modeling and its application in the development of high performance unmanned aerial vehicles. The process methodology, materials, post processing, and properties of its products are discussed in details. Successful examples of using this technology for making functional, lightweight, and high endurance unmanned aerial vehicles are also highlighted. In addition, major opportunities, limitations, and outlook of fused deposition modeling are also explored. The paper shows that the emerge of fused deposition modeling as a robust technique for unmanned aerial vehicles represents a good opportunity to produce compact, strong, lightweight structures, and functional parts with embedded electronic.

/pdf/fused-deposition-modeling-for-unmanned-aerial-vehicles-uavs-1kyvd34gb2.pdf

Fused Deposition Modeling for Unmanned Aerial Vehicles (UAVs): A Review

Unmanned aerial vehicles (UAVs) have shown promising benefits in many applications. This has been enabled by the emergence of additive manufacturing (AM), which give the designers a large amount of geometrical freedom. In this paper, a novel design process of fused deposition modelling (FDM) combining both topology and infill optimization is introduced for AM of high performance porous structures. Tensile testing of FDM printed samples was first carried out to study the effect of the build orientation on the mechanical properties of acrylonitrile butadiene styrene (ABS) samples. It was found that samples built perpendicular to the load axis were the weakest with a tensile strength of 29 MPa and Young's modulus of 1960 MPa. The materials properties were fed to the finite elements analysis (FEA) for geometrical topology optimisation, aiming to maximise stiffness and reduce weight of those parts. Afterwards, an infill optimisation was carried out on the topology optimised parts using different mesostructures such as honeycomb, triangular and rectangular to achieve high structural performance. The results showed that triangular pattern with 50% infill density had the lowest developed stresses, less mass and strain energy when compared to other structures. Optimum UAVs parts of a quadcopter were successfully manufactured, assembled, and tested.

/pdf/additive-manufacturing-of-porous-structures-for-unmanned-3wzjirvrns.pdf

Additive Manufacturing of Porous Structures for Unmanned Aerial Vehicles Applications

It is a very well-known fact that polyamide powders age during processing in laser sintering. Therefore, the recycling rate of used powder is typically limited to around 50 % and it has to be mixed with new, virgin powder, before the next build job can be started. The aging of the polymer powder between its production and processing, in contrast, has hardly been investigated so far and has received little attention. In order to investigate the effects of storage time, optical, thermal and rheological tests were carried out on two batches of PA2200 powder, which had been stored for 5.5 and 6.5 years respectively. Compared to freshly produced powders, aging effects were clearly visible.

Shelf life of polyamide 12 (pa2200) laser sintering powder

By monitoring the recoating process within polymer laser sintering production, it was shown that multiple powder-spread-flaws can be detected. Those groove-like flaws are expected to be the result of agglomerates jamming between the recoater and the last powder layer. This work is analyzing the interaction between powder-spread-flaws and part properties, showing the influence of the recoating process on the performance of laser sintering parts. Therefore, artificial powder-spread-flaws are applied to the build jobs of tensile test specimens which are measured and analyzed regarding the elongation at break, strength and fracture position. For the characteristics of the flaws, the artificial grooves are varied in depth and width. Furthermore, the position of the flaw is changed form mid part to close to surface areas. It was shown, that several flaws are visible at the part surface, resulting in stress concentration and reduced performance. But there are as well parts with flaw-layers, which are not visible after the build process on the part. Those parts can have significantly reduced mechanical properties as well.

Helge Klippstein

Papers

Fused Deposition Modeling for Unmanned Aerial Vehicles (UAVs): A Review

Additive Manufacturing of Porous Structures for Unmanned Aerial Vehicles Applications

Shelf life of polyamide 12 (pa2200) laser sintering powder

Powder spread flaws in polymer laser sintering and its influences on mechanical performance