CO2 LASER ABLATION MICROCHANNEL BASED ON KOCH FRACTAL PRINCIPLE

2019 ◽  
Vol 27 (05) ◽  
pp. 1950141
Author(s):  
XUEYE CHEN ◽  
YUE TIAN ◽  
SHUAI ZHANG
Keyword(s):  
Mixing Time ◽  
Laser System ◽  
Scanning Speed ◽  
Mixing Efficiency ◽  
Thermal Bonding ◽  
Manufacturing Method ◽  
Laser Systems ◽  
Koch Fractal ◽  
Koch Fractal Principle ◽  
The Impact

In this paper, we focussed on the processing power of CO2 laser systems and the impact of scanning speed, scanning power and number of scans on the quality of microchannels. We created microchannels which are based on the Koch fractal principle through a flexible and low-cost CO2 laser system. The processing and manufacturing method of Koch fractal micromixer on polymethyl methacrylate (PMMA) substrate was also studied. The microchannel structure based on the Koch fractal principle can increase the contact area and mixing time of the fluid and improve the mixing efficiency of the micromixer. In the experiment, our speed is 2, 4 and 6[Formula: see text]mm/s, the number of scans is 2/3/4 times and the power is 4, 8 and 12[Formula: see text]W. As the power and number of scans increase and the speed decreases, the width and depth of the microchannel are changed more clearly, which contributes to the successful thermal bonding of the Koch fractal micromixer and avoids thermal bonding due to overvoltage. By comparing the experimental data, we found that the width and depth of the channel are ideal when the speed is 2[Formula: see text]mm/s, the number of scans is 4 and the power is 12[Formula: see text]W. Because of the lower cost of PMMA, the use of CO2 laser systems to fabricate microchannels on PMMA substrates will have broad application value, reduce cost and be easier to manufacture.

Numerical simulation of three-dimensional passive micromixer based on the principle of Koch fractal

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Siyue Xiong ◽  
Xueye Chen
Keyword(s):  
Numerical Simulation ◽  
Fluid Flow ◽  
Cross Section ◽  
Three Dimensional ◽  
Mixing Efficiency ◽  
Mixing Performance ◽  
Chaotic Convection ◽  
Passive Micromixer ◽  
Koch Fractal ◽  
Koch Fractal Principle

Abstract In this paper, We arrange the obstacles based on the Koch fractal principle (OKF) in the micromixer. By changing the fluid flow and folding the fluid, a better mixing performance is achieved. We improve the mixing efficiency by placing OKF and changing the position of OKF, then we studied the influence of the number of OKF and the height of the micromixer on the mixing performance. The results show that when eight OKF are staggered in the microchannel and the height is 0.2 mm, the mixing efficiency of the OKF micromixer can reach 97.1%. Finally, we compared the velocity cross section and velocity streamline of the fluid, and analyzed the influence of OKF on the concentration trend. Through analysis, it is concluded that OKF can generate chaotic convection in the fluid, and enhance the mixing of fluids by generating vortices and folding the fluid. It can effectively improve the mixing efficiency of the micromixer.

Mixing performance of an electroosmotic micromixer with Koch fractal structure

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Siyue Xiong ◽  
Xueye Chen
Keyword(s):  
Fractal Structure ◽  
Low Voltage ◽  
Mixing Efficiency ◽  
Electrode Position ◽  
Fractal Structures ◽  
Mixing Performance ◽  
Electrode Voltage ◽  
Koch Fractal ◽  
Koch Fractal Principle ◽  
Short Time

Abstract In this paper, we have designed a Koch fractal electroosmotic micromixer (KFEM). A low-voltage electroosmotic micromixer. In order to optimize the electrode position, Koch microchannel is designed according to the Koch fractal principle and the electrode pairs based on the fractal are arranged. Then the effect of electrode voltage, electrode distribution positions, the number of electrode pairs, two kinds of Koch fractal structures, Reynolds (Re) number and the frequency of alternating current (AC) on the mixing performance are studied. The results show that the mixing efficiency can reach 99% in a short time when the AC voltage is 1 V, the AC frequency is 12 Hz and the electroosmotic micromixer has two sets of electrode pairs.

scholarly journals Pulsed UV Laser Processing of Carbosilane and Silazane Polymers

Materials ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 372 ◽  
Author(s):  
Samuel Ligon ◽  
Gurdial Blugan ◽  
Jakob Kuebler
Keyword(s):  
Laser Beam ◽  
Laser Processing ◽  
Scanning Speed ◽  
Inert Atmosphere ◽  
Laser Wavelength ◽  
Uv Laser ◽  
Glass Substrates ◽  
Polymer Precursors ◽  
Laser Systems ◽  
Pre Treatment

Freestanding SiCNO ceramic pieces with sub-mm features were produced by laser crosslinking of carbosilane and silazane polymer precursors followed by pyrolysis in inert atmosphere. Three different pulsed UV laser systems were investigated, and the influence of laser wavelength, operating power and scanning speed were all found to be important. Different photoinitiators were tested for the two lasers operating at 355 nm, while for the 266 nm laser, crosslinking occurred also without photoinitiator. Pre-treatment of glass substrates with fluorinated silanes was found to ease the release of green bodies during solvent development. Polymer crosslinking was observed with all three of the laser systems, as were bubbles, surface charring and in some cases ablation. By focusing the laser beam several millimeters above the surface of the resin, selective polymer crosslinking was observed exclusively.

The impact of photodarkening on mode instabilities in high-power fiber laser systems

2014 ◽  
Author(s):  
Cesar Jauregui ◽  
Hans-Jürgen Otto ◽  
Norbert Modsching ◽  
Oliver de Vries ◽  
Jens Limpert ◽  
...  
Keyword(s):  
Fiber Laser ◽  
High Power ◽  
Laser Systems ◽  
The Impact

scholarly journals Effect of Bottom Blowing Mode on Fluid Flow and Mixing Behavior in Converter

Metals ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 117
Author(s):  
Jiankun Sun ◽  
Jiangshan Zhang ◽  
Wenhui Lin ◽  
Xiaoming Feng ◽  
Qing Liu
Keyword(s):  
Refractory Lining ◽  
Mixing Time ◽  
Diffusion Path ◽  
Tracer Diffusion ◽  
Mixing Efficiency ◽  
Molten Bath ◽  
Local Flow ◽  
Average Value ◽  
Type Mode ◽  
Bottom Blowing

Bottom blowing agitation plays a crucial role in improving the reaction kinetics condition of molten bath during the steelmaking process. Herein, the influence of bottom blowing mode on the flow and mixing characteristics of molten bath and the abrasion characteristics of refractory lining in a 6:1 scaled-down model of a 100 t converter were investigated using physical and numerical simulations together. Eight bottom blowing modes were designed (uniform, three-point linear co-direction, three-point linear unco-direction, two-point linear, circumferential linear, A-type, V-type, and triangle alternating). The results indicated that bottom blowing mode has a significant effect on the local flow field at the inner ring of bottom tuyeres, the velocity interval distribution, and the turbulent kinetic energy, which in turn determines the tracer diffusion path and rate as well the mixing time of molten bath. Reasonable non-uniform bottom blowing modes promote the interaction between the various stirring sub-zones of the molten bath. Among them, the three-point linear co-direction mode and A-type mode have the highest mixing efficiency under the conditions of bottom blowing and combined blowing, respectively, which is superior to the uniform mode. In addition, the bottom blowing mode changed the location and degree of abrasion of the refractory lining, and the total abrasion of the non-uniform mode was reduced. The average value and fluctuation degree of integral wall shear stress for the A-type mode were minimal.

scholarly journals Human Dental Enamel and Dentin Structural Effects after Er:yag Laser Irradiation

2014 ◽  
Vol 15 (3) ◽  
pp. 283-287 ◽  
Author(s):  
Mateus Rodrigues Tonetto ◽  
Marcelo Ferrarezi de Andrade ◽  
Shelon Cristina Souza Pinto ◽  
Darlon Martins Lima ◽  
José Roberto Cury Saad ◽  
...  
Keyword(s):  
Laser Irradiation ◽  
Soft Tissues ◽  
Er:Yag Laser ◽  
Laser System ◽  
Dental Enamel ◽  
Target Tissue ◽  
Structural Effects ◽  
Ablation Process ◽  
Dental Tissues ◽  
Laser Systems

ABSTRACT Ideally projected to be applied on soft tissues, infrared lasers were improved by restorative dentistry to be used in hard dental tissues cavity preparations — namely enamel and dentin. This paper evidentiates the relevant aspects of infrared Erbium laser's action mechanism and its effects, and characterizes the different effects deriving from the laser's beams emission. The criteria for use and selection of optimal parameters for the correct application of laser systems and influence of supporting factors on the process, such as water amount and its presence in the ablation process, protection exerted by the plasma shielding and structural factors, which are indispensable in dental tissues cavity preparation related to restorative technique, are subordinated to optical modifications caused by the interaction of the energy dissipated by these laser light emission systems in the targeted tissue substrate. Clinical relevance Differences in the action of infrared Erbium laser system in regard to the nature of the ablation process and variations on the morphological aspects observed in the superficial structure of the target tissue irradiated, may be correlated to the structural optical modifications of the substrate produced by an interaction of the energy propagated by laser systems. How to cite this article Lima DM, Tonetto MR, de Mendonça AAM, Elossais AA, Saad JRC, de Andrade MF, Pinto SCS, Bandéca MC. Human Dental Enamel and Dentin Structural Effects after Er:yag Laser Irradiation. J Contemp Dent Pract 2014;15(3):283-287.

Impact response of a low-cost randomly oriented fiber foam core sandwich panel

2018 ◽  
Vol 52 (25) ◽  
pp. 3429-3444 ◽  
Author(s):  
Ezequiel Buenrostro ◽  
Daniel Whisler
Keyword(s):  
Mechanical Properties ◽  
Sandwich Panel ◽  
Low Cost ◽  
Three Dimensional ◽  
Cost Effective ◽  
Foam Core ◽  
Fiber Reinforced ◽  
Manufacturing Method ◽  
Manufacturing Techniques ◽  
The Impact

Three-dimensional fiber-reinforced foam cores may have improved mechanical properties under specific strain rates and fiber volumes. But its performance as a core in a composite sandwich structure has not been fully investigated. This study explored different manufacturing techniques for the three-dimensional fiber-reinforced foam core using existing literature as a guideline to provide a proof of concept for a low-cost and easily repeatable method comprised of readily available materials. The mechanical properties of the fiber-reinforced foam were determined using a three-point bend test and compared to unreinforced polyurethane foam. The foam was then used in a sandwich panel and subjected to dynamic loading by means of a gas gun (103 s−1). High-strain impact tests validated previously published studies by showing, qualitatively and quantitatively, an 18–20% reduction in the maximum force experienced by the fiber-reinforced core and its ability to dissipate the impact force in the foam core sandwich panel. The results show potential for this cost-effective manufacturing method to produce an improved composite foam core sandwich panel for applications where high-velocity impacts are probable. This has the potential to reduce manufacturing and operating costs while improving performance.

scholarly journals Effect of Process Parameters and Material Properties on Laser Micromachining of Microchannels

Micromachines ◽  
2019 ◽  
Vol 10 (2) ◽  
pp. 123 ◽  
Author(s):  
Matthew Benton ◽  
Mohammad Hossan ◽  
Prashanth Konari ◽  
Sanjeewa Gamagedara
Keyword(s):  
Process Parameters ◽  
Laser System ◽  
Three Dimensional ◽  
Microfluidic Devices ◽  
Scanning Speed ◽  
Transient Heat Conduction ◽  
Laser Micromachining ◽  
Rapid Phase ◽  
Widespread Application ◽  
Optimization Of Process Parameters

Laser micromachining has emerged as a promising technique for mass production of microfluidic devices. However, control and optimization of process parameters, and design of substrate materials are still ongoing challenges for the widespread application of laser micromachining. This article reports a systematic study on the effect of laser system parameters and thermo-physical properties of substrate materials on laser micromachining. Three dimensional transient heat conduction equation with a Gaussian laser heat source was solved using finite element based Multiphysics software COMSOL 5.2a. Large heat convection coefficients were used to consider the rapid phase transition of the material during the laser treatment. The depth of the laser cut was measured by removing material at a pre-set temperature. The grid independent analysis was performed for ensuring the accuracy of the model. The results show that laser power and scanning speed have a strong effect on the channel depth, while the level of focus of the laser beam contributes in determining both the depth and width of the channel. Higher thermal conductivity results deeper in cuts, in contrast the higher specific heat produces shallower channels for a given condition. These findings can help in designing and optimizing process parameters for laser micromachining of microfluidic devices.

scholarly journals Impact Toughness of FRTP Composites Produced by 3D Printing

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5654
Author(s):  
Milan Vaško ◽  
Milan Sága ◽  
Jaroslav Majko ◽  
Alan Vaško ◽  
Marián Handrik
Keyword(s):  
3D Printing ◽  
Mechanical Testing ◽  
Impact Load ◽  
Production Method ◽  
Research Area ◽  
New Production ◽  
Manufacturing Method ◽  
Continuous Fibre ◽  
Research Activities ◽  
The Impact

The additive manufacturing represents a new production method of composites reinforced with a continuous fibre. In recent times, the material produced by this new manufacturing method constituted a replacement for conventional materials—e.g., steel in many technical areas. As the research on FRTP composites is currently under way, the purpose of this article is to add information to the mosaic of studies in this research area. The scientific articles published until now have focused especially on mechanical testing, such as tensile and bending mechanical testing and their assessment. Therefore, the authors decided to carry out and assess the impact test of the FRTP composites produced by 3D printing because this area offers a large extent of research activities. We observed the influence of the reinforcement in the form of the micro-fibre carbon in the thermoplastic (Onyx) or a continuous reinforcement fibre in the lamina on the specimen’s behaviour during the impact load processes. The results of the experimental measurements show that the presence of a continuous fibre in the structure significantly affects the strength of the printed specimens; however, the design process of the printed object has to take into account the importance of selecting a suitable fibre type. The selection of a suitable strategy for arranging the fibre in the lamina and the direction of the impact load against the position of the fibre seem to be very important parameters.

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