scholarly journals Research Part Surface Position Influence on Metal Removal and Steady-State Roughness During Vibro-Abrasive Processing

2021 ◽  
Vol 2131 (5) ◽  
pp. 052020
Author(s):  
Aleksei Mordovtsev ◽  
Viktor Butenko ◽  
Aleksei Astashkin
Keyword(s):  
Steady State ◽  
Material Removal ◽  
Metal Removal ◽  
External Surface ◽  
Internal Surface ◽  
Triangular Prism ◽  
Internal Surfaces ◽  
Dependence Graphs ◽  
Part Surface ◽  
Experimental Researches

Abstract The paper is devoted to the study of part surface position and its influence on metal removal and steady-state rougness during vibro-abrasive processing. The article raises the differences between vibro-abrasive processing of external and internal part surfaces. Theoretical dependencies analysis for determination on part material removal and surface steady-state roughness is carried out. It is known that available theoretical dependencies do not take into account part surface position for material removal and the steady-state roughness calculation. Experimental researches to determine internal surface material removal with external surface isolation were carried out. The influence of part surface position on the steady-state roughness is investigated. Based on obtained experimental results, the dependence graphs of material removal and roughness on the processing time are constructed. The comparative analysis of the part surface position influence on material removal and the steady-state roughness during vibro-abrasive processing is carried out. The results showed that material removal volume from the internal surface more than from the external for short part length, however material removal volume from the external surfaces grows significantly in case of part length increasing, while from the internal surfaces is not significant. It is established that the internal surface steady-state roughness is ∼1.55 times higher than external surface steady-state roughness after processing in triangular prism 15×15, grit 16.

scholarly journals Phosphatidylethanolamine distribution and fluidity in outer and inner membranes of the gram-negative bacterium Erwinia carotovora

1980 ◽  
Vol 188 (1) ◽  
pp. 131-135 ◽  
Author(s):  
S D Shukla ◽  
C Green ◽  
J M Turner
Keyword(s):  
Outer Membrane ◽  
External Surface ◽  
Internal Surface ◽  
Erwinia Carotovora ◽  
Negative Bacterium ◽  
Membrane Structures ◽  
Membrane Bilayer ◽  
Inner Membrane ◽  
Gram Negative ◽  
Internal Surfaces

1. The distribution of phosphatidylethanolamine, the major lipid of Erwinia carotovora, was investigated in intact bacteria, spheroplasts and outer- and inner-membrane preparations, with the amino-group reagent 2,4,6-trinitrobenzenesulphonic acid. Only 4% was found on the external surface of the outer membrane with 30% on the internal surface, whereas the inner membrane had 27 and 38% on its external and internal surfaces respectively. Some comparative studies were made with three other bacteria. 2. The fluidity of the membranes of E. carotovora was studied by using the fluorescent probe 1,6-diphenylhexa-1,3,5-triene. Results were consistent with the hydrocarbon region of the outer membrane bilayer being less fluid than that of the inner one. 3. On the basis of these and other results a model for the outer- and inner-membrane structures of E. carotovora is proposed.

scholarly journals Reducing the Roughness of Internal Surface of an Additive Manufacturing Produced Steel Component by Chempolishing and Electropolishing

2018 ◽  
Author(s):  
Pawan Tyagi ◽  
Tobias Goulet ◽  
Christopher Riso ◽  
Robert Stephenson ◽  
Nitt Chuenprateep ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Counter Electrode ◽  
External Surface ◽  
Internal Surface ◽  
Critical Issue ◽  
Critical Factors ◽  
Post Processing ◽  
Steel Component ◽  
Internal Surfaces ◽  
Very High

Reducing the surface roughness of an additively manufactured (AM) component is one of the most critical factors in determining the suitability of an AM component. As produced surface roughness of an AM component is very high. This prohibits the direct utilization of AM components for the intended applications. For most of the engineering applications, surface roughness must be reduced significantly. Reducing surface roughness is exponentially more challenging for the internal surfaces of a component. This paper reports research in the area of post processing interior surfaces of an AM component. Electropolishing and chemical polishing (chempolishing) methods were applied to reduce the surface roughness of the internal surface. It was found that chempolishing was very effective in simultaneously reducing the internal and external surface roughness of steel AM components for any complicated AM shape and geometry. The electropolishing methodology employed was very effective in reducing the surface roughness of the internal or external surfaces as long as a counter electrode could be positioned in the proximity of the surface to be polished. However, electropolishing produced better performance on the outer surfaces as compared to chempolishing. This paper summarizes research efforts to tackle the critical issue of reducing the surface roughness of complex AM components.

Kerusakan Pada Material Pipa Air Bersih Akibat General Corrosion

2019 ◽  
Vol 16 (2) ◽  
Author(s):  
M. N. Setia Nusa
Keyword(s):  
Chemical Composition ◽  
Failure Analysis ◽  
External Surface ◽  
Internal Surface ◽  
General Corrosion ◽  
Water Pipe ◽  
Corrosion Attack ◽  
Corrosion Failure ◽  
Environment Factor

Water pipe of 4.5” diameter and has been operated for 8 year having failure due to corrosion attack on its external and internal surface. It is conducted failure analysis to find out the cause of corrosion by having testing examination of visual fractography, metalography,, SEM EDAX, hardness and chemical composition. Testing and examination results show that the failure / corroded pipe has a for in of general corrosion on the external surface due to environment factor or ground factor arround the pipe and on the internal surface was influenced by excessive root weld creating protrude which then causing turbolens and deposite to accelerate corrosion attack.Pipa berdiameter 4.5” yang berfungsi mengalirkan air bersih dan telah beroperasi selama 8 tahun, terjadi kerusakan berbentuk korosi pada permukaan luar pipa dan permukaan dalam. Untuk itu dilakukan analisa kerusakan untuk mengetahui penyebab terjadinya korosi dengan pengujian dan pemeriksaan secara visual,Fractography, Metallography, SEM, EDAX, Uji Kekerasan dan Uji Komposisi Kimia. Hasil pemeriksaan dan pengujian pada pipa yang rusak / korosi berbentuk jenis general korosi pada permukaan luar pipa yang diakibatkan faktor lingkungan atau tanah disekitar pipa, sedangkan pada bagian dalam pipa dipengaruhi oleh adanya lelehan pengelasan yang kurang sempurna sehingga menimbulkan benjolan yang mengakibatkan aliran air didalam pipa tidak lancar sehingga terjadi turbolensi yang menimbulkan endapan dan mengakibatkan percepatan terjadinya korosi.Keywords: Pipe, environtment, turbolens, corrosion, failure

scholarly journals Experimental Determination of the Heat Transfer Coefficient of Real Cooled Geometry Using Linear Regression Method

Energies ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 180
Author(s):  
Asif Ali ◽  
Lorenzo Cocchi ◽  
Alessio Picchi ◽  
Bruno Facchini
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Transfer Coefficient ◽  
Linear Regression ◽  
Surface Temperature ◽  
Transfer Coefficient ◽  
External Surface ◽  
Internal Surface ◽  
Regression Method ◽  
Thermal Transient

The scope of this work was to develop a technique based on the regression method and apply it on a real cooled geometry for measuring its internal heat transfer distribution. The proposed methodology is based upon an already available literature approach. For implementation of the methodology, the geometry is initially heated to a known steady temperature, followed by thermal transient, induced by injection of ambient air to its internal cooling system. During the thermal transient, external surface temperature of the geometry is recorded with the help of infrared camera. Then, a numerical procedure based upon a series of transient finite element analyses of the geometry is applied by using the obtained experimental data. The total test duration is divided into time steps, during which the heat flux on the internal surface is iteratively updated to target the measured external surface temperature. The final procured heat flux and internal surface temperature data of each time step is used to find the convective heat transfer coefficient via linear regression. This methodology is successfully implemented on three geometries: a circular duct, a blade with U-bend internal channel, and a cooled high pressure vane of real engine, with the help of a test rig developed at the University of Florence, Italy. The results are compared with the ones retrieved with similar approach available in the open literature, and the pros and cons of both methodologies are discussed in detail for each geometry.

scholarly journals Elastic-plastic transition stresses in a transversely isotropic thick-walled cylinder subjected to internal pressure and steady-state temperature

2009 ◽  
Vol 13 (4) ◽  
pp. 107-118 ◽  
Author(s):  
Thakur Pankaj
Keyword(s):  
Steady State ◽  
Internal Pressure ◽  
Isotropic Material ◽  
Internal Surface ◽  
Transversely Isotropic ◽  
Percentage Increase ◽  
Transversely Isotropic Material ◽  
Elastic Plastic ◽  
Steady State Temperature ◽  
Walled Cylinder

Elastic-plastic transitional stresses in a transversely isotropic thick-walled cylinder subjected to internal pressure and steady-state temperature have been derived by using Seth's transition theory. The combined effects of pressure and temperature has been presented graphically and discussed. It has been observed that at room temperature, thick-walled cylinder made of isotropic material yields at a high pressure at the internal surface as compared to cylinder made of transversely isotropic material. With the introduction of thermal effects isotropic/transversely isotropic cylinder yields at a lower pressure whereas cylinder made of isotropic material requires less percentage increase in pressure to become fully-plastic from its initial yielding as compared to cylinder made of transversely isotropic material.

scholarly journals Investigation an assisting electrode powder mixed electrical discharge machining of nonconductive ceramic

2021 ◽  
Author(s):  
Dragan Rodic ◽  
Marin Gostimirovic ◽  
Milenko Sekulic ◽  
Borislav Savkovic ◽  
Branko Strbac
Keyword(s):  
Surface Roughness ◽  
Tool Wear ◽  
Material Removal Rate ◽  
Electrical Discharge ◽  
Material Removal ◽  
Metal Removal ◽  
Electrical Discharge Machining ◽  
Removal Rate ◽  
Positive Effects ◽  
Assisting Electrode

Abstract It is well known that electrical discharge machining can be used in the processing of nonconductive materials. In order to improve the efficiency of machining modern engineering materials, existing electrical discharge machines are constantly being researched and improved or developed. The current machining of non-conductive materials is limited due to the relatively low material removal rate and high surface roughness. A possible technological improvement of electrical discharge machining can be achieved by innovations of existing processes. In this paper, a new approach for machining zirconium oxide is presented. It combines electrical discharge machining with assisting electrode and powder-mixed dielectric. The assisting electrode is used to enable electrical discharge machining of nonconductive material, while the powder-mixed dielectric is used to increase the material removal rate, reduce surface roughness, and decrease relative tool wear. The response surface method was used to generate classical mathematical models, analyzing the output performances of surface roughness, material removal rate and relative tool wear. Verification of the obtained models was performed based on a set of new experimental data. By combining these latest techniques, positive effects on machining performances are obtained. It was found that the surface roughness was reduced by 18%, the metal removal rate was increased by about 12% and the relative tool wear was reduced by up to 6% compared to electrical discharge machining with supported electrode without powder.

scholarly journals Plasma Catalysis: Distinguishing between Thermal and Chemical Effects

Catalysts ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 185 ◽  
Author(s):  
Guido Giammaria ◽  
Gerard van Rooij ◽  
Leon Lefferts
Keyword(s):  
Gas Phase ◽  
Surface Area ◽  
Thermal Effects ◽  
External Surface ◽  
Plasma Chemistry ◽  
Internal Surface ◽  
Plasma Power ◽  
External Surface Area ◽  
Internal Surface Area ◽  
Chemical Effects

The goal of this study is to develop a method to distinguish between plasma chemistry and thermal effects in a Dielectric Barrier Discharge nonequilibrium plasma containing a packed bed of porous particles. Decomposition of CaCO3 in Ar plasma is used as a model reaction and CaCO3 samples were prepared with different external surface area, via the particle size, as well as with different internal surface area, via pore morphology. Also, the effect of the CO2 in gas phase on the formation of products during plasma enhanced decomposition is measured. The internal surface area is not exposed to plasma and relates to thermal effect only, whereas both plasma and thermal effects occur at the external surface area. Decomposition rates were in our case found to be influenced by internal surface changes only and thermal decomposition is concluded to dominate. This is further supported by the slow response in the CO2 concentration at a timescale of typically 1 minute upon changes in discharge power. The thermal effect is estimated based on the kinetics of the CaCO3 decomposition, resulting in a temperature increase within 80 °C for plasma power from 0 to 6 W. In contrast, CO2 dissociation to CO and O2 is controlled by plasma chemistry as this reaction is thermodynamically impossible without plasma, in agreement with fast response within a few seconds of the CO concentration when changing plasma power. CO forms exclusively via consecutive dissociation of CO2 in the gas phase and not directly from CaCO3. In ongoing work, this methodology is used to distinguish between thermal effects and plasma–chemical effects in more reactive plasma, containing, e.g., H2.

scholarly journals Mode of Action of Chronotropic Agents in Cardiac Purkinje Fibers

1974 ◽  
Vol 64 (3) ◽  
pp. 320-342 ◽  
Author(s):  
Richard W. Tsien
Keyword(s):  
Surface Charge ◽  
External Surface ◽  
Membrane Surface ◽  
Internal Surface ◽  
Phosphodiesterase Inhibitors ◽  
Common Mechanism ◽  
Pacemaker Activity ◽  
Response Curves ◽  
Voltage Shift ◽  
Cardiac Purkinje Fibers

Hauswirth et al. (1968) proposed that epinephrine acts on iKK2 by adding its own positive charge to the external membrane surface near the iKK2 channel. This hypothesis was tested by using noncationic compounds, theophylline and R07-2956, which mimicked epinephrine's effects on pacemaker activity and on iKK2. In maximally effective doses, theophylline or R07-2956 occluded the effect of epinephrine, indicating a shared final common mechanism. Since theophylline and R07-2956 are noncationic at pH 7.4, the common mechanism cannot be a direct change in external surface charge. On the contrary, epinephrine does not interfere with the voltage shift produced by La+++, which is thought to modify the external surface charge. The results argue against the original hypothesis but leave open the possibility that an alteration in internal surface charge generates the observed voltage shift. The potency of theophylline and R07-2956 as phosphodiesterase inhibitors suggests that the final common mechanism begins with the elevation of intracellular cyclic AMP, leading to a saturable process which limits the voltage shift's magnitude. This hypothesis is used to generate dose-response curves describing the combined effects of epinephrine and theophylline, and these are compared with experimental data.

Laser Balancing Demonstration on a High-Speed Flexible Rotor

1979 ◽  
Author(s):  
R. S. DeMuth ◽  
D. P. Fleming ◽  
R. A. Rio
Keyword(s):  
Material Removal ◽  
High Speed ◽  
Metal Removal ◽  
Flexible Rotor ◽  
Test Rig ◽  
Laser Material ◽  
Removal Method ◽  
Before And After ◽  
Optical Configuration ◽  
Neodymium Glass

This paper describes a flexible rotor system used for two-plane laser balancing and an experimental demonstration of the laser material removal method for balancing. A laboratory test rotor was modified to accept balancing corrections using a laser metal removal method while the rotor is at operating speed. The laser setup hardware required to balance the rotor using two correction planes is described. The test rig optical configuration and a neodymium glass laser were assembled and calibrated for material removal rates. Rotor amplitudes before and after balancing, trial and correction weights, rotor speed during operation of laser, and balancing time were documented. The rotor was balanced through the first bending critical speed using the laser material removal procedure to apply trial weights and correction weights without stopping the rotor.

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