Macroscopic Effects of Surface Roughness in Confined Air-Flow

Materials: Processing, Characterization and Modeling of Novel Nano-Engineered and Surface Engineered Materials ◽

10.1115/imece2002-33831 ◽

2002 ◽

Cited By ~ 1

Author(s):

M’hamed Boutaous ◽

Patrick Bourgin

Keyword(s):

Experimental Data ◽

Mathematical Model ◽

Surface Roughness ◽

Spatial Distribution ◽

Surface Topography ◽

Air Flow ◽

Threshold Value ◽

Squeeze Flow ◽

Real Surface ◽

Plastic Films

The general framework deals with the winding of thin plastic films. It is well known by the man-of-the art that the “windability” of plastic films is mainly governed by their surface topography. One key issue is then to optimize their surface topography so that to improve the quality of the wound roll. In a previous work, we proposed a simple model which considers the flow of an air layer squeezed between a solid smooth substrate and a plastic film sample : it was shown experimentally that the macroscopic characteristics of the flow are connected to the film roughness, but how? To answer this question, we assimilate the confined air flow to a flow through a periodic array of cylinders. A mathematical model based on homogenization techniques was proposed, where the heights of the cylinders, their diameter and their spatial distribution are the governing parameters. In the present paper, we propose pertinent parameters which describes the real surface roughness of plastic films fairly well. The measurements were carried out by using a 3D roughness measurement device. The first observation is that the films roughness distribution is not uniform, but forms “packages” (agglomerates) giving place to large packs of roughness. We made a sampling at different levels expressed by the percentage of peaks exceeding some given height. The heights of the peaks over a threshold value are averaged and the corresponding averaged value will be regarded as the initial gap in the squeeze flow model. Now, the networks of cylinders is built as follows : • The cylinder diameters is the averaged width of the large peaks, • The distance between the cylinder axes is the mean value of the spatial distribution of the peaks. Thus, for each type of film, the threshold value will be the only adjustable parameter. Introducing these parameters into the mathematical model which predicts the evolution of the squeezed air layer and comparing to the experimental data, the following results are obtained: (1) It is possible to adjust one single parameter so that to obtain a very good agreement between the experimental data and the theoretical results. (2) The smoother the film, the more important the highest peaks are in terms of air leakage.

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Macroscopic Effects of Surface Roughness in Confined Air Flow

Journal of Fluids Engineering ◽

10.1115/1.1669034 ◽

2004 ◽

Vol 126 (2) ◽

pp. 216-222

Author(s):

M’hamed Boutaous ◽

Patrick Bourgin

Keyword(s):

Surface Roughness ◽

Air Flow ◽

Threshold Value ◽

Real Surface ◽

Plastic Films ◽

Wound Rolls ◽

Theoretical Predictions ◽

Flow Through ◽

Thin Plastic

The general framework deals with the winding of thin plastic films, in order to obtain good-quality rolls. This issue is tightly connected to the thickness of the residual air layer entrapped between the film layers. It is then of importance to optimize the surface topography of the films so that to improve the quality of the wound rolls. In a previous work, we proposed a simple model for the flow of an air layer squeezed between a solid smooth substrate and a plastic film sample: it was shown experimentally that the macroscopic characteristics of the flow are connected to the film roughness, but how? In order to answer this question, we assimilated the confined air flow to a flow through a periodic array of cylinders and a mathematical model based on homogenization techniques was developed. In the present paper, we search for pertinent parameters which describe the real surface roughness of plastic films. The experiments were carried out by using a 3-D roughness measurement device and the first observation is that the roughness distribution is not uniform. We made a sampling expressed by the percentage of peaks exceeding some given height threshold. The corresponding experimental parameters are used to define the network of cylinders. For each type of film, the threshold value is the only adjustable parameter and the following results are obtained: It is possible to adjust this parameter so that to obtain a very good agreement between the experimental data and the theoretical predictions. In addition, the smoother the film, the more important the highest peaks are in terms of air leakage.

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Air Flow in Yarn Texturing Nozzles

Journal of Engineering for Industry ◽

10.1115/1.3187118 ◽

1987 ◽

Vol 109 (3) ◽

pp. 197-202 ◽

Cited By ~ 10

Author(s):

M. Acar ◽

R. K. Turton ◽

G. R. Wray

Keyword(s):

Experimental Data ◽

Mathematical Model ◽

Experimental Work ◽

Air Flow ◽

Air Jet ◽

Continuous Filament ◽

The Mathematical Model ◽

Experimental Nozzle ◽

Good Agreement

The air-jet texturing process, a purely mechanical means of texturing continuous filament yarns, is described. Industrial texturing nozzles are reviewed and categorized in two groups, either as converging-diverging or cylindrical type nozzles. A mathematical model is developed for the complex airflow in cylindrical type texturing nozzles, and experimental data obtained from various nozzles verify the flow predicted by this model. The mathematical model is also shown to be in good agreement with the data obtained from a modified experimental nozzle, which has a trumpet shaped diverging exit. Further experimental work with a scaled-up model of a typical industrial texturing nozzle is also reported.

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Study and Optimisation of Process Parameter in Turning Of EN 45 - Spring Steel Material Under Dry And MQL Conditions

E3S Web of Conferences ◽

10.1051/e3sconf/202018401051 ◽

2020 ◽

Vol 184 ◽

pp. 01051

Author(s):

Kosaraju Satynarayana ◽

Kumkuma Rajkiran ◽

Kalemula Sai Kiran

Keyword(s):

Experimental Data ◽

Mathematical Model ◽

Surface Roughness ◽

Spring Steel ◽

Depth Of Cut ◽

Machining Parameters ◽

Anova Analysis ◽

Steel Material ◽

Magnetic Steel ◽

Minimum Quality

Minimum quality lubrication has shown a noticeable changes with machining outcomes. MQL is one of updated technologies that have been prevailing in contributions towards production and environment enhancement. Present papers deals with the turning of EN 45 steel material which is commonly known to be spring material. En 45 one of the magnetic steel material with low manganese and high amount of carbons is turned under dry and MQL condition. DOE has been prepared with L9 taguchi. Machining factors of speed (75, 100, 125 m/min), feed (0.1, 0.2, 0.3 mm/rev) and depth of cut (0.3, 0.6, 0.9 mm). The surface roughness were optimized by considering the machining parameters of speed, feed, and depth of cut. For both the condition dry and MQL it was observed that speed at 125m/min, feed at 0.1 and depth of cut at 0.3mm was found optimum condition. The regression equation and mathematical model was generated using the experimental data. Furthermore the ANOVA analysis was performed and observed that in case of dry turning speed found to be most influencing parameter and in case of MQL turning Feed was found to be most influencing parameter.

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Mathematical Modelling of Electric Discharge Machining of Al (6351)-SiC-B4C Hybrid Composite

International Journal of Recent Technology and Engineering - 2 ◽

10.35940/ijrte.d1053.1284s419 ◽

2020 ◽

Vol 8 (4S4) ◽

pp. 163-166

Keyword(s):

Experimental Data ◽

Mathematical Model ◽

Surface Roughness ◽

Mathematical Modelling ◽

Electric Discharge ◽

Electrode Wear ◽

Electric Discharge Machining ◽

Pulse On Time ◽

The Mathematical Model ◽

Time Pulse

The Electric Discharge Machining (EDM) has emerged as one of the major machining method for the machining of hard-to- machine materials and composites. This paper aims at creating a mathematical model for the machining of the Al(6351)-SiC-B4C composites based on the experimental data and compare the same to identify the level of errors between the mathematical model and the experimental results. This paper was aimed as an attempt to develop a mathematical model for the output parameters viz. Electrode Wear ratio and Surface roughness based on the input parameters viz. current, pulse-on-time, pulse duty-factor and gap voltage.

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Direct X-Ray Response of Self-Scanning Photodiode Arrays

Advances in X-ray Analysis ◽

10.1154/s0376030800008107 ◽

1975 ◽

Vol 19 ◽

pp. 587-596 ◽

Cited By ~ 2

Author(s):

Louis N. Koppel

Keyword(s):

Experimental Data ◽

Mathematical Model ◽

Spatial Distribution ◽

Spectral Sensitivity ◽

Low Energy ◽

Resolving Power ◽

X Rays ◽

X Ray ◽

Wavelength Dispersive Spectrometer ◽

Photodiode Arrays

Self-scanning photodiode arrays were tested for their ability to measure the spatial distribution of low-energy x rays in a wavelength dispersive spectrometer. X-ray spectral sensitivity was measured with a calibrated de source of nearly-monochromatic characteristic-x rays with photon energies in the range of 1.5 to 8 keV. Photodiode response was found to be linear with x-ray flux. Exposure to large doses of copper radiation did not effect sensitivity. A mathematical model that describes the experimental data is presented. We found that spatial resolving power was lowered by the dispersal of photogenerated charges. This effect was investigated with collimated beams and is described with a formula that predicts the loss of diode signals.

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Periodic Homogeneization Techniques As a Way to Account for Surface Roughness in a Confined Air Flow

10.1115/imece2001/fed-24904 ◽

2001 ◽

Author(s):

Patrick Bourgin ◽

M’hamed Boutaous ◽

Pierre Woehl

Keyword(s):

Surface Roughness ◽

Internal Stress ◽

High Speed ◽

Average Distance ◽

Air Flow ◽

Film Surface ◽

Roughness Coefficient ◽

Spatial Period ◽

Plastic Films ◽

Order Of Magnitude

Abstract The motivation of the study is concerned with high speed winding of plastic films (i.e. PET). During this process, some air is entrapped between the first wrap and the roll being wound. It is well known that the residual air layer between the plastic layers has a strong influence on the internal stress state within the roll. The surface roughness of the film plays an important role on these aerodynamic effects and consequently on the internal stress. Nevertheless, the mechanisms involved are not clarified yet. As a first step, an experimental study was conducted with the aim of characterizing the global flow kinetics of an air layer squeezed between a plastic film sample and a smooth substrate. In so doing, a new parameter was defined: some sort of a “dynamic roughness coefficient”. Nevertheless, the correlation between this parameter and those which describe the topography of a film surface (static) needed to be established. Using the tools of 3D roughness measurements, it was observed that the heights of the peaks and the mean distances between them are of the same order of magnitude as the average distance between the opposite surfaces. We therefore assimilated the surface topography to a periodic array of cylinders of known dimensions, their spatial period and their height being of the same order as the interlayer distance. In such conditions, the air flow squeezed in the space confined between the two surfaces is studied by using an approach based on periodic homogeneization techniques. The first tendencies indicate that a good qualitative agreement exists between the global experimental data and the theoretical results.

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Mathematical Model of Flat Surface Machining Inaccuracies due to Elastic Strains of Technological System

Mechanical Engineering and Computer Science ◽

10.24108/0918.0001426 ◽

2018 ◽

pp. 1-14 ◽

Cited By ~ 1

Author(s):

I. I. Kravchenko

Keyword(s):

Mathematical Model ◽

Vector Field ◽

Model Development ◽

Technological System ◽

Mutual Arrangement ◽

Real Surface ◽

Main Bearing ◽

Flat Surfaces ◽

Internal Surfaces ◽

Elastic Strains

The paper considers the mathematical model development technique to build a vector field of the shape deviations when machining flat surfaces of shell parts on multi-operational machines under conditions of anisotropic rigidity in technological system (TS). The technological system has an anisotropic rigidity, as its elastic strains do not obey the accepted concepts, i.e. the rigidity towards the coordinate axes of the machine is the same, and they occur only towards the external force. The record shows that the diagrams of elastic strains of machine units are substantially different from the circumference. The issues to ensure the specified accuracy require that there should be mathematical models describing kinematic models and physical processes of mechanical machining under conditions of the specific TS. There are such models for external and internal surfaces of rotation [2,3], which are successfully implemented in practice. Flat surfaces (FS) of shell parts (SP) are both assembly and processing datum surfaces. Therefore, on them special stipulations are made regarding deviations of shape and mutual arrangement. The axes of the main bearing holes are coordinated with respect to them. The joints that ensure leak tightness and distributed load on the product part are closed on these surfaces. The paper deals with the analytical construction of the vector field F, which describes with appropriate approximation the real surface obtained as a result of modeling the process of machining flat surfaces (MFS) through face milling under conditions of anisotropic properties.

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