scholarly journals Fabrication of anisotropic wetting surface with asymmetric structures using geometrical similarity and capillary force

2019 ◽  
Vol 7 (1) ◽  
Author(s):  
Ye-Eun Lee ◽  
Dong-Ki Lee ◽  
Young Hak Cho
Keyword(s):  
Capillary Force ◽  
Flow Characteristics ◽  
Longitudinal Direction ◽  
Liquid Droplets ◽  
Pdms Mold ◽  
Si Substrate ◽  
Asymmetric Flow ◽  
Molding Process ◽  
Asymmetric Structures ◽  
Geometrical Similarity

Abstract In the present study, we proposed a fabrication process of anisotropic wetting surfaces with asymmetric grooved parallelogram structures employing basic MEMS processes and micro transfer molding process. A Si substrate and a PDMS mold from Si master were easily self-aligned due to geometrical similarity (all Si wafer have same crystal planes) so that parallelogram microchannels could be formed between the Si substrate and PDMS mold. The parallelogram channels were filled with SU-8 via capillary force, and then the SU-8 parallelogram structures were transferred to an adhesive polymer film. Finally, we obtained an anisotropic wetting surface with SU-8 parallelogram structures, which showed the characteristics of anisotropic wetting and asymmetric flow. The liquid droplets could easily wet in the longitudinal direction of the structures, and the asymmetric flow characteristics of the droplets in the direction perpendicular to the longitudinal direction of the structures could be observed.

scholarly journals Study on Stability of a Novel Binder System Based on Palm Stearin in Metal Injection Moulding Application

2007 ◽  
Vol 4 (2) ◽  
pp. 1
Author(s):  
Muhammad Hussain Ismail ◽  
Norhamidi Muhamad ◽  
Aidah Jumahat ◽  
Istikamah Subuki ◽  
Mohd Afian Omar
Keyword(s):  
Injection Molding ◽  
Flow Characteristics ◽  
Injection Pressure ◽  
Palm Stearin ◽  
Steel Powder ◽  
Metal Injection Molding ◽  
Injection Molding Process ◽  
Binder System ◽  
Molding Process ◽  
Flow Activation Energy

Metal Injection Molding (MIM) is a wellestablished technology for manufacturing a variety of complex and small precision parts. In this paper, fundamental rheological characteristics of MIM feedstock using palm stearin are theoretically analyzed and presented. The feedstock consisted of gas atomized 316L stainless steel powder at three different particle size distributions and the binder system of palm stearin (PS) and polyethylene (PE). The powder loading used was 60vol % for all samples (monosize 16 µm, monosize 45 µm, and bimodal 16 µm + 45 µm) and the binder system of 40vol %(PS/PE = 40/60). The viscosity of MIM feedstock at different temperatures and shear rates was measured and evaluated. Results showed that, the feedstock containing palm stearin exhibited suitable rheological properties by increasing the fluidity of feedstock in MIM process. The rheological results also showed a pseudoplastic flow characteristics, which poses higher value of shear sensitivity (n) and lower value of flow activation energy (E), that are both favourable for injection molding process. The green parts were successfully injected and exhibited adequate strength for handling by optimizing the injection pressure and temperature.

Large Eddy Simulations of Film Cooling Flow Fields From Cylindrical and Shaped Holes

2008 ◽  
Author(s):  
D. H. Leedom ◽  
S. Acharya
Keyword(s):  
Film Cooling ◽  
Flow Characteristics ◽  
Flow Fields ◽  
Large Eddy Simulations ◽  
Delivery Tube ◽  
Asymmetric Flow ◽  
Specific Mass ◽  
Cooling Flow ◽  
Large Eddy ◽  
Coolant Delivery

Large Eddy Simulations (LES) of cylindrical, laterally diffused, and console holes are performed, and the resulting flow field data is presented. The motivation for performing LES is to enable more accurate simulations and to obtain a better understanding of the flow physics associated with complex hole shapes. The simulations include the coolant delivery tube and the feeding plenum chamber, and are performed for a specific mass flow rate of coolant per unit width of blade. A crossflow inlet is used on the plenum, and the resulting asymmetric flow characteristics are investigated. Coolant delivery tube flow fields are investigated in detail. Results show qualitative agreement with reported trends of improved film coverage with diffused and console holes.

Electroless Deposition of Gold Nanoparticles Over Silicon-based Substrates

2007 ◽  
Vol 990 ◽  
Author(s):  
Hassan Borteh ◽  
Nick Ferrell ◽  
Randall Butler ◽  
Susan Olesik ◽  
Derek Hansford
Keyword(s):  
Gold Nanoparticles ◽  
Metallic Nanoparticles ◽  
Pdms Mold ◽  
Molding Process ◽  
Transfer Molding ◽  
Adsorbed Proteins ◽  
Electron Beam Induced Current ◽  
Silicon Based ◽  
Inexpensive Procedure ◽  
Proteins And Peptides

ABSTRACTThe use of proteins and peptides to deposit and pattern metallic nanoparticles is becoming increasingly important. This method provides an inexpensive procedure to produced patterned and continuous metallic nanoparticles on variety of substrates such as silicon dioxide, silicon nitride, and polyimide. In this work, we explore the use of proteins and peptides for patterning and depositing gold nanoparticles. We used two different peptides or proteins for this experiment. One is 3XFLAG peptide from Sigma-Aldrich and the other one is bovine serum albumin (BSA). To pattern the peptides on the substrates we used two different methods, photolithography and micro-transfer molding. In photolithography, S1813 photoresist was patterned on the substrates through clean room process. In the micro-transfer molding process, a PDMS mold was made out of photoresist pattern. Polypropylmethacrylate (PPMA) was spin coated on the PDMS mold and stamped on the substrate in a high temperature. The proteins were adsorbed on the surface either physically or covalently. To deposit gold nanoparticles, the substrates with adsorbed proteins were covered with aqueous HAuCl4 solution. The proteins catalyze gold nanoparticles reduction from the solution. To characterize nanoparticles we used SEM and Electron Beam Induced Current (EBIC).

Design and Manufacturing of the Injection Mold for Metal-Inserted Rubber Parts Using CAD/CAM/CAE Technologies: A Case Study of the Engine Mounting

2008 ◽  
Author(s):  
Supasit Rodkwan ◽  
Wacharapong Chookaew ◽  
Rungtham Panyawipart ◽  
Chana Raksiri
Keyword(s):  
Flow Characteristics ◽  
Injection Pressure ◽  
Injection Mold ◽  
Butadiene Rubber ◽  
Molding Process ◽  
Engine Mounts ◽  
System A ◽  
Design And Manufacturing ◽  
Cad Cam ◽  
Trial And Error Method

In general, rubber parts used in automotive applications are designed and manufactured without any inserts; it is significant, however, that for certain parts, such as an engine mounting that, the metal core must be used to increase the compressive strength of products. With the lack of numerical tools used to predict the rubber flow characteristics and the interaction between rubber and metal insert during the molding process, mold designers must rely on their experience and the trial-and-error method to design molds. Therefore, in this research, an application of CAD/CAM/CAE on the design and manufacturing of an injection mold for the engine mounting rubber made of a blend of Natural Rubber (NR) and AcryloNitrile-Butadiene Rubber (NBR) is performed. A CAD model of the part is constructed and then a two-cavity mold as well as various runner patterns and gate positions are designed and further analyzed using CAE. Subsequently, with use of the CAM system, a metal-inserted mold and related components are manufactured and used to produce the rubber engine mounts on the vertical rubber injection machine. The empirical and numerical resulting parameters, including part geometry, injection pressure, and part temperature at various injection stages, correlate well. This information provides mold designers and manufacturers a better understanding of the rubber behavior during curing in the metal-inserted rubber molding process so that various mold components can properly designed and effectively used. Consequently, better mold and product quality with less defects as well as reduced production time can be obtained.

scholarly journals High-speed transport of liquid droplets in magnetic tubular microactuators

2018 ◽  
Vol 4 (12) ◽  
pp. eaau8767 ◽  
Author(s):  
Wenwei Lei ◽  
Guanglei Hou ◽  
Mingjie Liu ◽  
Qinfeng Rong ◽  
Yichao Xu ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Capillary Force ◽  
High Speed ◽  
Magnetic Particles ◽  
Liquid Droplets ◽  
Open Surface ◽  
Liquid Motion ◽  
Practical Applications ◽  
Closed Tube ◽  
Droplet Splitting

Magnetic field–induced droplet actuation has attracted substantial research interest in recent years. However, current magnetic-controlled liquids depend primarily on magnetic particles added to a droplet, which serves as the actuator on an open surface. These liquids inevitably suffer from droplet splitting with the magnetic particles or disengaging with the magnet, possibly leading to sample contamination, which severely limits their transport speed and practical applications. Here, we report a simple and additive-free method to fabricate magnetic tubular microactuators for manipulating liquid droplets by magnetism-induced asymmetric deformation, which generates an adjustable capillary force to propel liquids. These magnetic tubular microactuators can drive various liquid droplets with controllable velocity and direction. A speed of 10 cm s−1can be achieved, representing the highest speed of liquid motion driven by an external stimulus–induced capillary force in a closed tube found so far.

scholarly journals Study on Stability of a Novel Binder System Based on Palm Stearin in Metal Injection Moulding Application

2007 ◽  
Vol 4 (2) ◽  
pp. 1 ◽  
Author(s):  
Muhammad Hussain Ismail ◽  
Norhamidi Muhamad ◽  
Aidah Jumahat ◽  
Istikamah Subuki ◽  
Mohd Afian Omar
Keyword(s):  
Injection Molding ◽  
Flow Characteristics ◽  
Injection Pressure ◽  
Palm Stearin ◽  
Steel Powder ◽  
Metal Injection Molding ◽  
Injection Molding Process ◽  
Binder System ◽  
Molding Process ◽  
Flow Activation Energy

Metal Injection Molding (MIM) is a wellestablished technology for manufacturing a variety of complex and small precision parts. In this paper, fundamental rheological characteristics of MIM feedstock using palm stearin are theoretically analyzed and presented. The feedstock consisted of gas atomized 316L stainless steel powder at three different particle size distributions and the binder system of palm stearin (PS) and polyethylene (PE). The powder loading used was 60vol % for all samples (monosize 16 µm, monosize 45 µm, and bimodal 16 µm + 45 µm) and the binder system of 40vol %(PS/PE = 40/60). The viscosity of MIM feedstock at different temperatures and shear rates was measured and evaluated. Results showed that, the feedstock containing palm stearin exhibited suitable rheological properties by increasing the fluidity of feedstock in MIM process. The rheological results also showed a pseudoplastic flow characteristics, which poses higher value of shear sensitivity (n) and lower value of flow activation energy (E), that are both favourable for injection molding process. The green parts were successfully injected and exhibited adequate strength for handling by optimizing the injection pressure and temperature.

Effect of In-Plane Fiber Tow Waviness Upon the Tensile Strength Characteristics of Fiber Reinforced Composites of Carbon/Epoxy AS4/3501-6

2015 ◽  
Author(s):  
Sai Bhargav Pottavathri ◽  
Rajeev Nair ◽  
Ramazan Asmatulu
Keyword(s):  
Stiffness Matrix ◽  
High Stress ◽  
Local Stress ◽  
Longitudinal Direction ◽  
Stress Concentrations ◽  
Molding Process ◽  
Buckling Mode ◽  
Severity Factor ◽  
Fiber Waviness ◽  
Mechanical Methods

The purpose of this study was to investigate the strength and effectiveness when induced with ‘in-plane fiber tow waviness’ in a composite ply of carbon/epoxy AS4/3501-6. Fiber waviness is usually induced by infusion processes and inherent in fabric architectures. Composite structural details like ply drops and ply joints can cause serious fiber misalignment. These are usually dependent on parameters such as ply thickness, percentage of plies dropped, and mold geometry and pressure, and pressure of the resin which slides the dry fibers during the resin transfer molding process. Fiber disorientation due to fiber tow waviness in ‘in-plane’ direction has been the subject of recent studies on wind turbine blade materials and other aerospace laminates with reports of compression strengths and failure strains that are borderline, depending upon the reinforcement architecture, matrix resin and environment. Waviness is expected to reduce compressive strength due to two primary factors. The fibers may be oriented in such a way that the geometry that results because of the orientation may exacerbate the basic fiber, strand, or layer buckling mode of failure. The waviness could also shift the fiber orientation of the axis of the ply longitudinal direction which eventually results in matrix dominated failures for plies normally orientated in the primary load direction (0°). Both global and local stress & strain values generated by the finite element model were validated by the traditional mechanical methods using ply/local stiffness matrix and global/reduced stiffness matrix. A precise geometry of waviness on different materials was modeled with different wave severity factor and a parametric study was conducted. Three different defects were modeled where the angle of misalignment ranged from 5 to 15 degrees with wavelength ranging from 1 inch to 1.5 inches and amplitude ranging from 0.03 inches to 0.7 inches. This revealed the effect of ‘in-plane fiber tow waviness’ on the stress distribution and loss of strength in carbon/epoxy AS4/3501-6. The results clearly show that the effect of ‘in-plane fiber tow waviness’ leads to resin rich areas which causes high stress concentrations and decrease in the strength ratio, ultimately leading to delamination’s.

To Fabricate Bragg Grating on D-Shaped Optical Fibre by Micro-Pressing Method

2013 ◽  
Vol 311 ◽  
pp. 472-476
Author(s):  
Fang Chang Hsu ◽  
Farn Tsei Chen ◽  
Chi Ting Ho
Keyword(s):  
Optical Fiber ◽  
Interference Lithography ◽  
Bragg Grating ◽  
Test Results ◽  
Pdms Mold ◽  
Molding Process ◽  
Replication Process ◽  
Pressing Method ◽  
The Core ◽  
Surface Grating

In this paper, we proposed a method to fabricate a D-shaped optical fiber of Bragg surface grating filter component by D-shaped fiber polishing along with photolithography、holographic interference lithography technologies and micro-molding process. The optical fiber was side-polished until it reaches the core of fiber. The master Bragg grating was first fabricated on the positive photoresister by using the holography interference lithography, then the patterned resist was used as a mother mold to transfer the pattern onto a hard polydimethylsiloxane (hPDMS)/ polydimethylsiloxane (PDMS) mold. The gratings pattern on hPDMS/PDMS was then transferred onto the UV polymer on the surface of a D-shaped fiber using a UV replication process. The transmission spectra of the resulting gratings were measured, with test results showing the transmission dip of -17dB , and 3-dB-transmission bandwidth of 9nm.

On the Prediction of Hydrodynamic Forces Acting on a Ship Moving at Constant Drift

2006 ◽  
Author(s):  
N. Sulficker Ali ◽  
G. Dhinesh ◽  
K. Murali ◽  
V. Anantha Subramanian
Keyword(s):  
Fluid Dynamics ◽  
Computational Study ◽  
Flow Characteristics ◽  
Lateral Force ◽  
Asymmetric Flow ◽  
Mean Velocity ◽  
Drift Angle ◽  
Towing Tank ◽  
Computational Fluid Dynamics Cfd ◽  
Yaw Moment

The effect of drift angle on a ship is investigated through towing tank tests and using Computational Fluid Dynamics (CFD). Resistance and wave elevations obtained from the computational study are validated with experimental results. Detailed free surface, mean velocity and pressure flow fields on the hull surface are obtained from the computational study for Fn ranging from 0.16 to 0.22 and for drift angle β = 0, 5 and 10°. The lateral force, yaw moment and asymmetric flow characteristics are brought out in the computational study.

The effect of longitudinal microstriations and their profiles on the drag of flat plates

1999 ◽  
Vol 213 (8) ◽  
pp. 775-785 ◽  
Author(s):  
K Parker ◽  
A T Sayers
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
Flow Characteristics ◽  
Longitudinal Direction ◽  
Turbulent Energy ◽  
Viscous Drag ◽  
Turbulent Shear ◽  
Flat Plates ◽  
Lower Velocity ◽  
Aspect Ratios

The use of surface modifications as a means of reducing viscous drag on a body has potential aerodynamic and hydrodynamic applications. V-grooves of specific dimensions are machined in a longitudinal direction onto the surface of a smooth plate and the resulting effect on the drag force of the plate is observed. Experiments show that V-grooves (riblets) could reduce turbulent skin friction drag by up to 7 per cent, depending on the size of the groove. The drag-reducing performance of riblets with aspect ratios, h/s, of 0.22 and 1 are examined. A boundary layer analysis of the turbulent flow characteristics over the smooth surface and the riblet surfaces indicated an increase in the laminar sublayer thickness and local Reynolds number while reducing the boundary layer thickness for the ribbed surfaces. A maximum drag reduction of 6.83 per cent was recorded for the surface covered with the symmetric riblet, at a Reynolds number of 117 101. It is felt that riblets hamper the momentum and turbulent energy exchange from regions of high velocity to lower-velocity regions. Riblets impede the cross-flow of stream-wise vortices that prevail in the viscous sublayer of a turbulent boundary layer. By suppressing these streamwise vortices, turbulent mixing and hence turbulent shear stress are reduced. Results obtained agree with results suggested from research elsewhere.

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