High-Speed Additive Manufacturing Through High-Aspect-Ratio Nozzles

JOM ◽  
2018 ◽  
Vol 70 (3) ◽  
pp. 284-291 ◽  
Author(s):  
Leon Shaw ◽  
Mashfiqul Islam ◽  
Jie Li ◽  
Ling Li ◽  
S. M. Imran Ayub
Keyword(s):  
Additive Manufacturing ◽  
Aspect Ratio ◽  
High Aspect Ratio ◽  
High Speed

scholarly journals Numerical Investigation into Flutter and Flutter-Buffet Phenomena for a Swept Wing and a Curved Planform Wing

2019 ◽  
Vol 2019 ◽  
pp. 1-19 ◽  
Author(s):  
Mario Rosario Chiarelli ◽  
Salvatore Bonomo
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
High Speed ◽  
Sensitivity Study ◽  
Fuel Saving ◽  
Swept Wing ◽  
Instability Condition ◽  
Aspect Ratios ◽  
Numerical Studies ◽  
Classical Flutter

The results of numerical studies carried out on high-aspect-ratio wings with different planforms are discussed: the transonic regime is analysed for a swept wing and a curved planform wing. The wings have similar aspect ratios and similar aerodynamic profiles. The analyses were carried out by CFD and FE techniques, and the reliability of the numerical aerodynamic results was proven by a sensitivity study. Analysing the performances of the two wings demonstrated that in transonic flight conditions, a noticeable drag reduction can be obtained by adopting a curved planform wing. In addition, for such a wing, the aeroelastic instability condition, consisting in a classical flutter, is postponed compared to a conventional swept wing, for which a flutter-buffet instability occurs. In a preliminary manner, the study shows that, for a curved planform wing, the high speed buffet is not an issue and at the same time notable fuel saving can be achieved.

A Study on the Characteristics of Micro Deep Hole Machining Processes

2007 ◽  
Vol 364-366 ◽  
pp. 566-571
Author(s):  
Tae Il Seo ◽  
Dong Woo Kim ◽  
Myeong Woo Cho ◽  
Eung Sug Lee
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
High Speed ◽  
Printed Circuit Boards ◽  
Hole Drilling ◽  
Deep Hole ◽  
Machining Processes ◽  
Deep Hole Drilling ◽  
Micro Drilling ◽  
Hole Machining

Recently, the trends of industrial products move towards more miniaturization, variety and mass production. Micro drilling which take high precision in cutting work is required to perform more micro hole and high speed working. Especially, Micro deep hole drilling is becoming more important in a wide spectrum of precision production industries, ranging from the production of automotive fuel injection nozzle, watch and camera parts, medical needles, and thick multilayered Printed Circuit Boards(PCB) that are demanded for very high density electric circuitry. The industries of precision production require smaller holes, high aspect ratio and high speed working for micro deep hole drilling. However the undesirable characteristics of micro drilling is the small signal to noise ratios, wandering motion of drill, high aspect ratio and the increase of cutting force as cutting depth increases. In order to optimize cutting conditions, an experimental study on the characteristics of micro deep hole machining processes using a tool dynamometer was carried out. And additionally, microscope with built-in an inspection monitor showed the relationship between burr in workpieces and chip form of micro drill machining.

Enabling Robust Copper Fill of High Aspect Ratio Through Silicon Vias

2010 ◽  
Vol 2010 (1) ◽  
pp. 000176-000179
Author(s):  
Mark Willey ◽  
Damo Srinivas ◽  
Sesha Varadarajan ◽  
David Porter ◽  
Easwar Srinivasan ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
High Speed ◽  
High Performance ◽  
Process Window ◽  
Seed Technology ◽  
Aspect Ratios ◽  
Reducing Costs ◽  
Electroplating Process ◽  
Silicon Vias

Today's Through Silicon Via (TSV) processes are limited to aspect ratios of 10:1. High performance logic devices drive the need for aspect ratios approaching 20:1 in order to achieve the desired performance while simultaneously reducing costs. The reduced via area required on the wafer enables the designer to utilize less real estate on the die to reduce cost or to potentially add redundant vias to improve yield. However, current conventional processes and techniques are not capable of achieving robust fill on aspect ratios greater than 12:1. This presentation will highlight the technical challenges in achieving robust copper fill on super high aspect ratio TSV structures. Additionally, a compelling, economic solution pathway will be presented that integrates a low temperature conformal high quality dielectric isolation layer, a high step coverage Cu barrier / seed technology and a void free high speed electroplating process with a wide process window that could accelerate the adoption of the high aspect ratio TSV design schemes.

Experimental Investigation of the Evaporation and Stability of a Meniscus in a Flat Microchannel

2011 ◽  
Vol 312-315 ◽  
pp. 1178-1183
Author(s):  
Souad Harmand ◽  
Khellil Sefiane ◽  
Rachid Bennacer ◽  
Nicolas Lancial
Keyword(s):  
Experimental Investigation ◽  
Aspect Ratio ◽  
High Aspect Ratio ◽  
High Speed ◽  
Evaporation Rate ◽  
Liquid Meniscus ◽  
Line Region ◽  
Three Phase ◽  
Increasing Temperature ◽  
Insight Into

We present the results of an experimental investigation of the evaporation of a liquid meniscus in a high aspect ratio micro-channel. The study investigates evaporation rates of a stationary liquid meniscus in a high aspect ratio microchannel, the wall of which is electrically heated using transparent resistive coating. Four different liquids are used as working fluids. We report on the dependence of the measured overall evaporation rate on the applied power. The results indicate, and consistently, that the evaporation rate increases with the applied power then peaks before declining. In order to gain insight into these results, we used thermographic infra red imaging to map the temperature field on the external wall of the microchannel. The measurements show that there is a good correlation between the maximum in the evaporative rate and the onset of instabilities of the interface. These instabilities, to our mind, are induced by an increasing temperature gradient along the microchannel wall around the three phase contact line region. These instabilities are revealed by a high speed camera used to record the behaviour of the interface during evaporation.

scholarly journals Thin-Rib and High Aspect Ratio Non-Stochastic Scaffolds by Vacuum Assisted Investment Casting

2019 ◽  
Vol 3 (2) ◽  
pp. 34
Author(s):  
Vitor H. Carneiro ◽  
Hélder Puga ◽  
Nuno Peixinho ◽  
José Meireles
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
Aspect Ratio ◽  
Investment Casting ◽  
High Aspect Ratio ◽  
Cellular Materials ◽  
Investment Model ◽  
Transportation Industry ◽  
Small Deviations

Cellular structures are a classic route to obtain high values of specific mechanical properties. This characteristic is advantageous in many fields, from diverse areas such as packaging, transportation industry, and/or medical implants. Recent studies have employed additive manufacturing and casting techniques to obtain non-stochastic cellular materials, thus, generating an in situ control on the overall mechanical properties. Both techniques display issues, such as lack of control at a microstructural level in the additive manufacturing of metallic alloys and the difficulty in casting thin-rib cellular materials (e.g., metallic scaffolds). To mitigate these problems, this study shows a combination of additive manufacturing and investment casting, in which vacuum is used to assist the filling of thin-rib and high aspect-ratio scaffolds. The process uses 3D printing to produce the investment model. Even though, vacuum is fundamental to allow a complete filling of the models, the temperatures of both mold and casting are important to the success of this route. Minimum temperatures of 250 °C for the mold and 700 °C for the casting must be used to guarantee a successful casting. Cast samples shown small deviations relatively to the initial CAD model, mainly small expansions in rib length and contraction in rib thickness may be observed. However, these changes may be advantageous to obtain higher values of aspect ratio in the final samples.

High-speed microprobe for roughness measurements in high-aspect-ratio microstructures

2017 ◽  
Vol 28 (3) ◽  
pp. 034009 ◽  
Author(s):  
Lutz Doering ◽  
Uwe Brand ◽  
Sebastian Bütefisch ◽  
Thomas Ahbe ◽  
Thomas Weimann ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
High Speed ◽  
Roughness Measurements
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