Magnetorheological micro jet polishing (MMJP) technology has great potential for polishing components with complex surfaces, cavities, and microstructures. However, there is a lack of in-depth and systematic research ...
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Magnetorheological micro jet polishing (MMJP) technology has great potential for polishing components with complex surfaces, cavities, and microstructures. However, there is a lack of in-depth and systematic research on the material removal characteristics of MMJP under different processing parameters, which hinders its engineering application. This study developed a numerical model for MMJP using the Volume of Fluid (VOF) multiphase flow model and the K-W turbulence model, which was used to analyze the interaction between the flow field and the workpiece during the polishing process. To clarify the material removal process, the material removal mechanism of MMJP was investigated. The forces acting on individual abrasives in the flow field were analyzed, and a material removal model for MMJP was established based on the Preston equation. Additionally, a combined approach of simulation and experimentation was used to study the effects of different processing parameters on material removal and polishing performance. The experimental results were consistent with the numerical predictions, demonstrating the reliability of the CFD model. Finally, an orthogonal optimization experiment was designed to determine the influence hierarchy of various process factors on the polishing results. Using the optimal process parameter combination, aluminum alloy workpieces were polished, with the surface roughness reduced from 355 nm to 253 nm. This study provides theoretical support and processing guidance for the industrial application of MMJP.
Viscosity reduces when heavy crude oil forms oil-in-water (o/w) emulsion in water or brine and can be easily transported through the pipeline. In this study, an oil/water (o/w) emulsion was prepared using crude oil an...
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Viscosity reduces when heavy crude oil forms oil-in-water (o/w) emulsion in water or brine and can be easily transported through the pipeline. In this study, an oil/water (o/w) emulsion was prepared using crude oil and water as continuous and dispersed phases using two different non-ionic surfactants, hydrogenated castor oil ethoxylate with 40 mol of ethylene oxide, and castor oil ethoxylate with 40 mol of ethylene oxide. The advantage of using non-ionic surfactants is that they are biodegradable, are not affected by the salinity of water and their emulsion can be easily separated. An interaction plot and Box-Behnken Design (BBD) approach were used to optimize oil: water ratio, pH, and surfactant concentration to minimize the consumption of chemicals. O/W emulsions were characterized by optical microscopy, drop size distribution, and Attenuated total reflectance (ATR)-Fourier transform infrared spectroscopy (FTIR). A stability study was performed by gravity separation and turbiscan analysis. 2-10 v/v % toluene and n-heptane were mixed with crude oil for dilution, and viscosities were compared with the result obtained from the emulsification of crude oil using two different 1 v/v % nonionic surfactants. Using COMSOL Multi-Physics software, a pressure drop calculation was performed, and a velocity profile was developed considering the transportation of crude oil as well as o/w emulsion (containing hydrogenated castor oil ethoxylate with 40 mol of ethylene oxide as surfactant) through the pipeline.
Chlorine dioxide is a well known powerful disinfectant. Although there are several chemical and electrochemical methods developed for on-line chlorine dioxide generation, the details are mostly confined as patents. We...
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Chlorine dioxide is a well known powerful disinfectant. Although there are several chemical and electrochemical methods developed for on-line chlorine dioxide generation, the details are mostly confined as patents. We studied in this work the electrochemical generation of dissolved chlorine dioxide from an un-buffered solution of sodium chlorite and sodium chloride mixture in an un-divided electrochemical cell set-up with RuO2-coated-Ti anode and Pt-coated-Ti cathode under constant current mode. Various processparameters including feed flow rate ( 10 to 150 ml/min), feed solution pH (2.3 to 9.4), concentration of sodium chloride ( 0 to 170 mM), concentration of sodium chlorite ( 0 to 7.7 mM), and the applied current ( 100 to 1,200 mA) were optimized. Experiments were conducted by performing single pass experiments, with no circulation. The current efficiency and the power consumption were calculated for the optimized conditions, and compared with IrO2 electrode of our previous investigation.
This article aims to investigate the means to obtain optimal hot stamping processparameters and the influence of the stochastic variability of these parameters on forming quality. A multi-objective stochastic approac...
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This article aims to investigate the means to obtain optimal hot stamping processparameters and the influence of the stochastic variability of these parameters on forming quality. A multi-objective stochastic approach, integrating response surface methodology (RSM), multi-objective genetic algorithm optimization non-dominated sorting genetic algorithm II (NSGA-II) and the Monte Carlo simulation (MCS) method is proposed in this article to achieve this goal. RSM was used to establish the relationship between the processparameters and forming quality indices. NSGA-II was utilized to obtain a Pareto frontier, which consists of a series of optimal processparameters. The MCS method was employed to study and reduce the influence of a stochastic property of these processparameters on forming quality. The results confirmed the efficiency of the proposed multi-objective stochastic approach during optimization of the hot stamping process. Robust optimal processparameters guaranteeing good forming quality were also obtained using this approach.
A "one step" finite element method called the Inverse Approach (IA) has been developed to estimate the large elasto-plastic strains in thin sheet metallic parts obtained by deep drawing. In this work the dev...
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A "one step" finite element method called the Inverse Approach (IA) has been developed to estimate the large elasto-plastic strains in thin sheet metallic parts obtained by deep drawing. In this work the development status of the IA for the analysis and optimum process design of industrial parts is presented. The first part of the paper deals with the improvements on the analysis with analytical formula to consider the restraining forces due to the drawbeads. The second part deals with the optimization procedure combining the IA, a BFGS algorithm and analytical sensitivity analysis to optimize material parameters and restraining forces. Two applications are presented to demonstrate the applicability of the proposed optimization procedure. (C) 2003 Elsevier B.V. All rights reserved.
作者:
Long, YangtaoHe, HuCent South Univ
Coll Mech & Elect Engn State Key Lab Precis Mfg Extreme Serv Performance Changsha 410083 Peoples R China
Wire bonding remains widely utilized in numerous products today due to its mature technology and costeffectiveness. However, improper bonding parameters can result in damage to the metal layer at the bonding interface...
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Wire bonding remains widely utilized in numerous products today due to its mature technology and costeffectiveness. However, improper bonding parameters can result in damage to the metal layer at the bonding interface, leading to the formation of "craters." Therefore, it is worthwhile for continuous optimization of the bonding process. The presented work employs finite element modeling to investigate the thermo-compression ultrasonic bonding process, focusing on the impact of bonding parameters on the stress at the bond pad interface. It was observed that the main determinant of bonding strength is the peripheral ring area, where the FAB adheres to the bond pad. Furthermore, excessive bonding pressure was found to result in over compression and subsequent separation at the bonding interface. In the experiment, it was discovered that bonding force had the most significant influence on shear strength, followed by ultrasonic current, whereas bonding time exhibited a less pronounced effect. However, there was no significant difference in pull strength under different bonding processparameters. The optimized processparameters were determined to be 110 mA for ultrasonic current, 25 ms for bonding time, and 20 gf for bonding force. Finally, the mapping relationship between the bonding ball size parameter (bonding ring area S : the inner ring represents the capillary's inner diameter, while the outer ring represents the capillary's contact with the outermost boundary) and shear strength was determined: as S increases, the shear strength decreases. This indicates that this dimensional parameter has the potential to serve as a nondestructive indicator for predicting shear strength.
Chlorine dioxide is potentially a powerful oxidant with environmentally compatible application in several strategic areas relating to pollution control typically for water disinfection, and its sustained production is...
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Chlorine dioxide is potentially a powerful oxidant with environmentally compatible application in several strategic areas relating to pollution control typically for water disinfection, and its sustained production is a key factor for its successful application. Although increased attention has been paid for on-line chlorine dioxide generation by several chemical and electrochemical methods, the details are mostly confined as patents. We studied in this work the electrochemical generation of chlorine dioxide from an un-buffered solution of sodium chlorite and sodium chloride mixture in an un-divided electrochemical cell under constant current mode, with a view to optimize various processparameters, which have a direct bearing on the chlorine dioxide formation efficiency under laboratory conditions. The effect of feed flow rate (10-150 ml min(-1)), feed solution pH (2.3-5.0), concentration of sodium chloride (0-169.4 mM), concentration of sodium chlorite (0-7.7 mM), and the applied current (100-1200 mA) on the formation of dissolved ClO2 gas in solution and the pH of the product-containing solution was investigated by performing single pass experiments, with no circulation, in a cell set-up with Ti/IrO2 anode and Ti/Pt cathode. The current efficiency and the power consumption were calculated for the optimized conditions. (C) 2008 Elsevier B.V. All rights reserved.
This paper investigates the influence of carrier gas flow on the external flow field of coaxial powder feeding nozzle. FLUENT software was adopted to establish gas-solid two-phase flow. The simulation of powder stream...
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This paper investigates the influence of carrier gas flow on the external flow field of coaxial powder feeding nozzle. FLUENT software was adopted to establish gas-solid two-phase flow. The simulation of powder stream field under different carrier gas flow was also carried out. Results show that the larger the flow of carrier gas is, the higher the gas flow field velocity at the nozzle outlet is. At the same time, the concentration at the convergence point is lower, and the convergent point is maintained at 0.015 m. Under the condition of 4 L/min, the powder flow convergence is good. When it exceeds 4 L/min, powder spot diameter increases. The experiment of powder aggregation and laser cladding forming were completed, which shows that the forming effect is the best one under the condition of 4 L/min. It is consistent with the simulation analysis results and has a high reference to the optimization of the processparameters of coaxial nozzle.
Three-dimensional free-bending is a new and an advanced forming technology to manufacture the complex metal hollow components with continuously varying radius. In this study, the principle, process analysis, and the C...
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Three-dimensional free-bending is a new and an advanced forming technology to manufacture the complex metal hollow components with continuously varying radius. In this study, the principle, process analysis, and the CNC control of free-bending were introduced in detail. The characteristics of the free-bending process, such as the motion trace scope of bending die and the stress variation in the free-bending process, were numerically investigated through finite element method using ABAQUS finite element code. With the simulation model, the material correction factor (Km) of copper was determined and the correction factor (Kc) for the clearance between the tube and bending die was also proposed. Moreover, the effects of the key processparameters including the clearance between the tube and bending die (Delta c), the distance between the center of the bending die and the head of guide sleeve (A), and the axial feeding velocity (v) on the forming quality of the tubular bending components were studied as well. Through the finite element simulation and analysis, the optimum parameters (Km, Kc, Delta c, A, and v) used in the free-bending process of the tubular component are summarized and the forming process design of the copper tubular component was also obtained. Based on the forming process design, the simulation and bending test of the copper tubular component were carried out, and the dimensions of the bending components gave a very good agreement with the results obtained from finite element modeling. Furthermore, there was no obvious cross section distortion, excessive thickening, and thinning of wall thickness of the formed tubular components. It is concluded that the three-dimensional free-bending technology is a novel forming process used to manufacture a sound complex three-dimensional hollow component with asymmetric cross sections and continuous varying radii.
Electrochemical machining has the characteristics of no loss of processing cathode, high processing efficiency and good accuracy, and can process complex deep special-shaped holes at one time with simple feed motion. ...
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Electrochemical machining has the characteristics of no loss of processing cathode, high processing efficiency and good accuracy, and can process complex deep special-shaped holes at one time with simple feed motion. This paper uses electrochemical machining technology to solve the problem of complex deep special-shaped holes that are difficult to machine and designs a three-sided feed-type cathode. Firstly, the gap electric field was simulated and analyzed using COMSOL simulation software. The simulation results show that the width of the insulating layer on both sides of the end and wall of the cathode key tooth slot tip is 0.5 mm, and the rounded angle formed by the deep special-shaped hole key tooth tip is reduced to 0.11 mm after machining. Secondly, a simulation analysis of the gap electrolyte flow field and temperature field was carried out. The simulation results show that the gap electrolyte flow velocity is higher and the flow uniformity is better for the cathode structure with 10 through-holes, and the temperature of the gap electrolyte can be controlled below 30 & DEG;C, which significantly improves the forming accuracy of the deep special-shaped hole. Finally, process tests were carried out and the best combination of processparameters was obtained by the S/N ratio and grey correlation method. The simulation effectively shortens the cathode development cycle and optimizes the cathode structure.
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