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The purpose of this paper is to describe a procedure to simulate impact-driven liquid jets by computational fluid dynamics (CFD). The proposed CFD model is used to investigate nozzle flow behavior under ultra-high injection pressure and jet velocities generated by the impact driven method (IDM).

A CFD technique was employed to simulate the jet generation process. The injection process was simulated by using a two-phase flow mixture model, while the projectile motion was modeled the moving mesh technique. CFD results were compared with experimental results from jets generated by the IDM.

The paper provides a procedure to simulate impact-driven liquid jets by CFD. The validation shows reasonable agreement to previous experimental results. The pressure fluctuations inside the nozzle cavity strongly affect the liquid jet formation. The average jet velocity and the injection pressure depends mainly on the impact momentum and the volume of liquid in the nozzle, while the nozzle flow behavior (pressure fluctuation) depends mainly on the liquid volume and the impact velocity.

Results may slightly deviate from the actual phenomena due to two assumptions which are the liquid compressibility depends only on the rate of change of pressure respected to the liquid volume and the super cavitation process in the generation process is not taken into account.

Results from this study will be useful for further designs of the nozzle and impact conditions for applications of jet cutting, jet penetration, needle free injection, or any related areas.

This study presents the first success of employing a commercial code with additional user defined function to calculate the complex phenomena in the nozzle flow and jet injection generated by the IDM.

This study aims to experimentally investigate the effect of the powder material characteristics on the qualities of the binder jetting additive manufacturing parts both before and after post processing (sintering).

Three different types of the 316L stainless steel powder feedstock with various mean particle sizes and size distributions were studied. The influence of the powder particle size distributions and pore sizes on the powder bed packing densities and on the dynamics of the binder droplet-powder bed interactions were characterized. In addition, the surface roughness and densities of these parts both in the green state and after sintering were studied.

The results revealed the significant role of the powder feedstock characteristics on the liquid binder/powder bed interaction and consequently on the dimensional accuracies of the green parts. It was observed that the parts printed with the smaller mean particle sizes resulted in better surface finish and higher final densities after sintering. Furthermore, the hardness of the sintered parts produced with smaller powder particles exhibited higher values compared to the parts fabricated with the larger particles. On the other hand, larger particle sizes are advantageous for various green part qualities including the dimensional accuracies, green part densities and surface roughness.

This study establishes more comprehensive correlations between the powder feedstock characteristics and various quality criteria of the printed binder jetting components in both green and sintered states. These correlation are of critical importance in choosing the optimal process parameters for a given material system.

This study aims to describe the effects of capillary forces or action, viscosity, gravity and inertia via the computational fluid dynamics (CFD) analysis. The study also includes distribution of the binder droplet over the powder bed after interacting from different heights.

Additive manufacturing (AM) has revolutionized many industries. Binder jetting (BJT) is a powder-based AM method that enables the production of complex components for a wide range of applications. The pre-densification interaction of binder and powder is vital among various parameters that can affect the BJT performance. In this study, BJT process is studied for the binder interaction with the powder bed of SS316L. The effect of the droplet-powder distance is thoroughly analysed. Two different droplet heights are considered, namely, h1 (zero) and h2 (9.89 mm).

The capillary and inertial effects are predominant, as the distance affects these parameters significantly. The binder spreading and penetration depth onto the powder bed is influenced directly by the distance of the binder droplet. The former increases with an increase in latter. The binder distribution over the powder bed, whether uniform or not, is studied by the stream traces. The penetration depth of the binder was also observed along the cross-section of the powder bed through the same.

In this work, the authors have developed a more accurate representative discrete element method of the powder bed and CFD analysis of binder droplet spreading and penetration inside the powder bed using Flow-3D. Moreover, the importance of the splashing due to the binder’s droplet height is observed. If splashing occurs, it will produce distortion in the powder, resulting in a void in the final part.

The purpose of this paper is to present an exhaustive review of research studies and activities in the inkjet printing of conductive materials.

This paper gives a detailed literature survey of research carried out in inkjet printing of conductive materials.

This article explains the inkjet printing process and the various types of conductive inks. It then examines the various factors that affect the quality of inkjet printed interconnects such as printing parameters, materials and substrate treatments. Methods of characterising both the inkjet printing process and the electrical properties of printed conductive materials are also presented. Finally relevant applications of this technology are described.

Inkjet printing is currently one of the cheapest direct write techniques for manufacturing. The use of this technique in electronic manufacturing, where interconnects and other conductive features are required is an area of increasing relevance to the fields of electronics manufacturing, packaging and assembly. This review paper would therefore be of great value and interest to this community.

This review paper aims to introduce the inkjet printing as a tool for fabrication of flexible/wearable sensors. It summarizes inkjet printing techniques including various modes of operation, commonly used substrates and inks, commercially available inkjet printers and variables affecting the printing process. More focus is on the drop-on-demand printing mode, a strongly considered printing technique for patterning conductive lines on flexible and stretchable substrates. As inkjet-printed patterns are influenced by various variables related to its conductivity, resistivity, durability and dimensions of printed patterns, the main printing parameters (e.g. printing multilayers, inks sintering, surface treatment, cartridge specifications and printing process parameters) are reported. The embedded approaches of adding electronic components (e.g. surface-mounted and optoelectronic devices) to the stretchable circuit are also included.

In this paper, inkjet printing techniques for fabrication of flexible/stretchable circuits will be reviewed. Specifically, the various modes of operation, commonly used substrates and inks and variables affecting the printing process will be presented. Next, examples of inkjet-printed electronic devices will be demonstrated. These devices will be compared to their rigid counterpart in terms of ease of implementation and electrical behavior for wearable sensor applications. Finally, a summary of key findings and future research opportunities will be presented.

In conclusion, it is evident that the technology of inkjet printing is becoming a competitor to traditional lithography fabrication techniques, as it has the advantage of being low cost and less complex. In particular, this technique has demonstrated great capabilities in the area of flexible/stretchable electronics and sensors. Various inkjet printing methods have been presented with emphasis on their principle of operation and their commercial availability. In addition, the components of a general inkjet printing process have been discussed in details. Several factors affect the resulting printed patterns in terms of conductivity, resistivity, durability and geometry.

The paper focuses on flexible/stretchable optoelectronic devices which could be implemented in stretchable circuits. Furthermore, the importance and challenges related to printing highly conductive and highly stretchable lines, as well as reliable electronic devices, and interfacing them with external circuitry for power transmission, data acquisition and signal conditioning have been highlighted and discussed. Although several fabrication techniques have been recently developed to allow patterning conductive lines on a rubber substrate, the fabrication of fully stretchable wearable sensors remains limited which needs future research in this area for the advancement of wearable sensors.

This paper aims to find the optimal deposition conditions for achieving the homogenous structure of the silver layers onto three types of polymeric substrates as well as on the rigid substrates. For this reason, the detailed investigation of the silver-based layers deposited at different technological conditions by microscopic methods is presented in this paper.

The special test pattern has been designed and deposited at different substrate temperatures by using two types of generally available silver-based nano-inks. Cross-sections and 3D profiles of the deposited silver layers have been profoundly analysed by using the optical profiler Sensofar S Neox on the generally used polymeric (PI, PET and PEN) and rigid substrates (951 and 9K7 LTCC, glass and alumina).

The results prove the strong correlation between the substrate temperature during the deposition process and the final shape of the created structure which has the a direct impact on the layers’ homogeneity. The results also prove the theory of the coffee ring effect creation in the inkjet printing technology.

The main benefit of this paper lies in the possibility of the homogeneity achievement of the deposited silver-based layers on the several polymeric and rigid substrates by managing the temperature during the deposition. The paper also offers the comparative study of nano-inks’ behaviour on several polymeric and rigid substrates.