Values Of Roughness Parameters Research Articles

Evaluation of Surface Roughness and Defect Formation after The Machining of Sintered Aluminum Alloy AlSi10Mg.

This article presents selected issues related to the workpiece surface quality after machining by the laser sintering of AlSi10MG alloy powder. The surfaces of the workpiece were prepared and machined by longitudinal turning with tools made of sintered carbides. The occurrence of breaches on the machined material surface was found, which negatively influence the values of 3D surface roughness parameters. The occurring phenomena were analyzed and proposals for their explanation were made. Guidelines for the machining of workpieces achieved by the laser sintering of powders were developed. The lowest value of the 3D roughness parameters was obtained for f = 0.06 mm/rev, ap = 0.5–1.0 mm, and for the nose radius of cutting insert rε = 0.8 mm. The results of research on the effect of cutting parameters on the values of parameters describing the surface quality are presented. Topography measurements and 3D surface roughness parameters are presented, as well as the results of a microscopic 3D surface analysis. Taguchi’s method was used in the research methodology.

Towards an Intelligent Approach for the Restitution of Physical Soil Parameters

The analysis of the radar response on natural surfaces has been subject of intense research during the last decades in the field of remote sensing. Unless the availability of accurate values of surface roughness parameter, the restitution of soil moisture from radar backscattering signal can constantly provide inaccurate estimates. Characterization of soil roughness is not fully understood, so a wide range of roughness values can be obtained for the same studied surface when using different measurement methodologies. Various studies have shown a weak agreement between experimental measurements of soil physical parameters and theoretical values under natural conditions. Due to this nonlinearity and its ill-posedness, the inversion of backscattering radar signal on soils for restitution of physical soil parameters is particularly complex. The aim of the present work is the restitution of soil physical parameters from backscattered radar signal using an adapted backscattering model to the soil proposed description. As our study focuses on little rough soils, we have adopted in this work a multi-layered modified multiscale bi-dimensional Small Perturbation Model (2D MLS SPM). Subsequently, we propose a new way of describing the dielectric constant, with the aim of including air fractions in the multiscale multilayer description of the soil. Calculating the dielectric constant is based on the consideration of a soil comprising two phases, a fraction of soil, and an air fraction. For the inversion method, a methodology of coupling between neural networks (NN) and genetic algorithms (GA) was carried on in order to restitute the physical properties of the soil. Samples were generated by the original MLS 2D SPM followed by a neural network to obtain the statistic soil moisture and MLS roughness parameters algorithm. thereafter, these restored values were modelled by the genetic algorithms to resolve, in part or in whole, the disagreement between the retrieval and original values.

Istraživanje i optimizacija uticaja parametara obrade na hrapavost površine kod obrade AISI 4340 čelika

This paper focuses on the experimental investigation of machining parameters such as cutting speed, feed rate and depth of cut influence over surface roughness parameters (Ra, Ry and Rt) during turning AISI 4340 steel. Further, in order to achieve smaller surface roughness parameter values, the machining parameters are optimized using Taguchi's technique Signal-to-Noise ratio (S/N ratio). Analysis of Variance (ANOVA) is performed to determine the most contributing factor that influences the surface roughness parameters. It is observed that the feed rate is the most significant factor contributing by 70.50%, depth of cut by 18.54% and cutting speed by 9.15%. From the optimum condition obtained, a confirmation experiment is performed and the results obtained shows that the surface roughness parameter values are reduced by 31.63% than the designed experimental values.

Class Ratio Transform with an Application to Describing the Roughness Anisotropy of Natural Rock Joints

In this study, we explore the potential of class ratio transform with an application to describing the roughness anisotropy of natural rock joints. Roughness smooth coefficient, used for suitably smoothing the roughness parameter values to realize an anisotropic model, is proposed to represent the apparent anisotropy of surface roughness. The geometric irregularities of roughness parameters in polar plots allow transforming to a regular roughness asperity pattern, which can be readily approximated by the ellipse function. The joint roughness coefficients in different orientations of natural rock joints were measured and revealed to be identical after applying the smoothing process using the class ratio transform method. The results show that the roughness smooth coefficient increases with sample size but decreases as azimuthal interval narrows. This method demonstrates the ability in describing the roughness anisotropy and inferring the roughness parameters Z2, Rp, and .

The Influence of Cutting Parameters on Surface Topography During Turning Marine Pump Shafts

Abstract One of the greatest problems of modern production techniques is the achievement of an appropriate quality at minimal costs and accompanied by the production efficiency increase. Therefore, while designing the production process. The technology used should have a considerable influence on the durability and reliability of machine parts to be produced. During finish treatment, the final dimensions as well as functional properties are imparted to a given element by application of proper treatment type. The engineer has a range of production techniques to choose for the proper surface layer formation. Conventional turning machines belong to the basic equipment of ships, because in sea conditions, they enable the execution of a spare part or carrying out the necessary operations in the process of their regeneration. The use of modern cutting tools makes it possible to obtain a surface with low values of surface roughness parameters. The use of new generation cutting inserts on conventional lathes can cause problems for operators. The lack of the ability to ensure proper of treatment condition and setting errors of cutting tools contribute to the damage of the cutting insert or the surface of the workpiece. The article presents the results of influence of different cutting parameters on surface topography during turning process of stainless steel. A shaft made of 304L stainless steel was used for the research. The cutting process was carried out on a universal TUM 25B x 500 centre lathes. During the turning the following machining parameters were used: cutting speed Vc [m/min], feed f [mm/rev] and depth of cut ap [mm].The turning process was conducted by a cutting tool with CCGT 09T302 UM, CCGT 09T304 UM and CCGT 09T308 UM inserts. Measurement of surface topography was carried out by T8000 profilometer.

Surface quality simulation with neural networks in AZ91D Mg alloy milling

The mathematical model presented in this paper describes the process of milling AZ91D Mg alloy with the TiAlN-coated tool. The experimental data from the neural network training served to determine the effect of various milling parameters on the surface roughness of the workpiece. The 2D roughness measurements were taken on the end-faces of specimens and focused on the set of three parameters – Ra, Rz and RSm. The tests were performed at constant parameters (tool geometry, workpiece strength properties and technological machine properties), variable parameters (cutting speed, feed per tooth, depth of cut) and output variables (Ra, Rz, Rsm). The simulations were executed by means of the artificial neural networks, modelled with Statistica Neural Network software. Two types of neural networks were employed: MLP (Multilayered Perceptron) and RBF (Radial Basis Function). The comparative analysis showed that the discrepancy between the results of simulation and the results obtained from experimental tests is on an acceptable level, not exceeding 15%. The above result confirms that ANNs can be successfully used as a tool for a selection of technological parameters, enabling obtaining the desired values of surface roughness parameters without the need for time-consuming machining tests.

Progress in simplifying hydrologic model parameterization for broad applications to post‐wildfire flooding and debris‐flow hazards

AbstractPredicting the timing of overland flow in burned watersheds can help to estimate debris‐flow timing and the location of debris‐flow initiation. Numerical models can produce flow predictions, but they are limited by our knowledge of appropriate model parameters. Moreover, opportunities to test and calibrate model parameters in post‐wildfire settings are limited by available data (measurements of debris‐flow timing are rare). In this study, we use a unique data set of rainfall and flow‐timing data to test the extent to which model parameters can be generalized from an individual watershed to other watersheds (0.01 km 2 to >1km 2) within a burned area. Simulations suggest that a single, low, saturated hydraulic conductivity value can be used in post‐wildfire landscapes with reasonable results. By contrast, we found that watershed‐scale effective Manning roughness parameter values decrease as a power‐law function of basin drainage area. Thus a Manning roughness parameter calibrated for a single basin within a burned area may not provide adequate results in a different watershed. However, when flow velocity is modeled independently for hillslopes and channels, and different roughness parameters are used for those morphometric units, there is no drainage‐area dependence on the roughness parameters. Moreover, we found that it was possible to use field‐measured grain size data to parameterize the roughness for both hillslopes and channels. Thus our results show that, employing this generalizable approach, it is possible to use field measurements to fully parameterize a model that produces peak flow timing to within a few minutes in storms lasting several hours. Further, we demonstrate how model simulations can be leveraged to identify areas within a watershed that are most susceptible to debris flows. This modeling approach could be used for decision making in hazardous burned areas and would be especially useful in ungaged basins. © 2019 John Wiley & Sons, Ltd.

Relationship between edge roughness in mask pattern and charging in plasma etching

AbstractThe edge roughness (ER) developed in the mask pattern during the plasma etching process harms the perfect pattern transformation from mask to substrate. To understand and ultimately manipulate plasma‐induced ER, this study investigated the interplay between charging and nanoscale roughness of an isolated rough mask hole in the plasma etching process using a modeling framework, which consisted of a surface etching module, a surface charging module, and a profile evolution module. Specifically, on the one hand, the distributions of the spatial electric field (E‐field) and etching rate were simulated for the rough mask surface being etched. It is revealed that the distribution of the etching rate is similar with that of E‐field clinging to the mask surface, and both of them reach their maximum strength around the mask hole edge and gradually becomes uniform/nonuniform with the decrease of the value of the dominant amplitude/wavelength of roughness; on the other hand, a string algorithm was used to simulate the evolution rule for a rough profile of a mask hole with etching time under various values of roughness parameters. The simulated evolution of the profile has good agreement with experimental observation. The charging effect contributes to the enhancement of the root mean square roughness. Additionally, the influence of roughness parameters on the charging time versus root mean square was also examined. The mechanism behind these results was analyzed systematically. This study will greatly contribute toward improving the physical and chemical properties of the mask or optimizing the etching technique.

Thermohydraulic performance enhancement of a new hybrid duct solar air heater with inclined rib roughness

In this work, a new hybrid duct configuration of solar air heater is analytically investigated to improve the thermal performance of the system. The proposed design consists of parallel pass air flow paths with rectangular and triangular cross sections at upper and lower sides of the absorber plate. Both the sides of the absorber plates are roughened with inclined shape ribs. The roughness parameters are configured with relative roughness pitch at the bottom of the plate (Pb/eb) of 4–16, relative roughness height of e/Dh ranges from 0.021 to 0.050 and relative angle of arc of (α/60) 0.5–1. Based on the analytical results it is concluded that the maximum effective efficiency is 80.1% for roughness pitch of 8, relative roughness height of 0.021 and relative angle of arc of (α/60) 0.5, at the mass flow rate of 0.045 kg/s at the upper and lower duct. The effect of the mass flow fraction (i) on the thermal performance of the solar air heater is also analyzed. The system improves the thermal and effective efficiency by 22.4% and 18.1% when compared to conventional rectangular duct parallel pass SAH. The design plots are developed to find the optimum values of roughness parameters with respect to ambient conditions.

Combination of spectroscopic ellipsometry and spectroscopic reflectometry with including light scattering in the optical characterization of randomly rough silicon surfaces covered by native oxide layers

A combined method of spectroscopic ellipsometry and spectroscopic reflectometry is employed for the optical characterization of randomly rough surfaces of silicon single crystal covered with very thin native oxide layers within spectral range 197–1240 nm (1.0–6.3 eV). It is shown that random roughness of the samples of this system exhibits a wide interval of spatial frequencies so that the Rayleigh–Rice theory, scalar diffraction theory for coherent light and scalar diffraction theory with including light scattering must be used to achieve good fits of experimental data. The ellipsometric data are compatible with the Rayleigh–Rice theory within the entire spectral range while the reflectometric data must be processed separately within two sub-ranges using two different theoretical approaches. In one of the sub-ranges the combination of Rayleigh–Rice theory and scalar diffraction theory for coherent light is utilized for obtaining good fits of the corresponding experimental data of reflectance. Within the latter sub-range the scalar diffraction theory including the influence of light scattering on reflectance enables us to achieve good fits. Further, it is shown that using this combined method the values of basic roughness parameters, i.e. the rms values of heights, autocorrelation lengths and rms values of slopes of roughness irregularities, can be determined together with thickness values of the native oxide layers. A comparison of the results achieved optically with those determined by atomic force microscopy is performed. The assessment of efficiency of spectroscopic ellipsometry and spectroscopic reflectometry in characterizing random roughness with the wide interval of spatial frequencies is also presented.

Overview of mechanistic particle resuspension models: comparison with compilation of experimental data

In this study, several mechanistic models for particle removal from substrates were introduced and their predictive ability was tested. Empirically optimized parameters for a selected set of particle-substrate combinations were obtained and the ability of these models to predict resuspension for a large number of particle-substrate combinations and flow conditions using the published experimental data was explored. Our analysis showed that accurate predictions for a broad spectrum of particle-substrate combinations require accounting for substrate roughness and particle non-sphericity. From analysis of our compiled experimental data set, it was determined that the shear velocities required for particle resuspension follow a log-normal distribution, with geometric standard deviations in the range of 1.4 to 1.7. From comparison of the calculated and measured critical shear velocities, we found that a critical roughness parameter value of Δc = 0.774 is a reasonable estimate for most real substrates. We show that the combination of parameters determined from our study and models that account for roughness and particle non-sphericity, it is possible to predict particle resuspension from most substrates with reasonable accuracy.

Research about the quality of the surface after turning out of duralumin alloy

This paper describes a study concerning the inner turning of a piece of duralumin, using 6 values of the feed. The shapes and micro-geometry of the resulting chips have been observed experimentally and these are explained by the large deformations in the cutting area. The processed surfaces, both by enlarging them to a microscope and by measuring the roughness have been experimentally studied. Also, the sections of chips are analysed, giving the theoretical and real dimension values, also interpreted on the basis of the deformations in the cutting area. Also, values of roughness parameters are presented.

Comparative Study Regarding the Surface Roughness of Highly Viscous Flowable Composites After Immersion in Acidic Drinks

The aim of the present study was to assess, by profilometry, the effect of different immersion regimes in Coca-Cola drink on the surface roughness of two highly viscous flowable composite resins. The studied materials were Gradia Direct LoFlo (GC Corporation,Tokyo, Japan) and Micro Esthetic flow-viscous (Bisico, Germany). Fifteen cylindrical samples having the of 5 mm and the thickness of 2 mm were made from each material using plastic molds placed on glass plates. The samples were light-cured for 40s on both sides through the glass plates, to ensure complete polymerization of the material. They were divided into two groups as follows: Group I. Gradia Direct LoFlo and Group II. Micro Esthetic flow-viscous. Specimens of each group were then randomly divided into 5 subgroups. In subgroup A (control group) 4 samples were kept only in artificial saliva. In subgroups B-E (each having 4 samples) the samples were immersed in Coca-Cola drink according to 4 different protocols. The mean values of roughness parameters, Ra, were calculated. The Kolmogorov-Smirnov normality test was used to determine the distribution of data in groups. ANOVA and Tukey post hoc statistical tests were used to compare the results from the groups. For both materials, the highest surface roughness was determined for the samples that were submerged 7 times/day in Coca Cola. The assessment of surface microstructure of the samples, after immersion, revealed for both materials a statistically significant increase of Ra values.

Investigating silk yield and morphological changes in silk fibres obtained from silkworms fed with Ag and/or $$\hbox {TiO}_{2}$$ nanoparticles

Natural polymers like silk can be augmented in vivo with metallic elements to improve their intrinsic properties and stability. This study demonstrates the uptake of Ag and/or $$\hbox {TiO}_{2}$$ nanoparticles as diet supplements by silkworms. Nanoparticles dose on morphological changes in silk fibroin fibres and a change in overall silk yield was investigated. Though significant fibre reinforcement with Ag and/or $$\hbox {TiO}_{2}$$ was not noticed; an increase of 6% in the silk production was observed when silkworms fed with a particular composition of $$\hbox {Ag} + \hbox {TiO}_{2}$$ nanoparticles (0.37 mM each) in their diet. Here, an average diameter of the degummed silk fibre was $${\sim }10.91 \upmu \hbox {M}$$ with a roughness parameter value $$R_{\mathrm{q}}$$ being 134. This value is comparable to silk fibres obtained from silkworms fed with $$\hbox {Ag} + \hbox {TiO}_{2}$$ (0.22 $$+$$ 0.53 mM) nanoparticles and this $$R_{\mathrm{q}}$$ value was also low when compared to the other tested compositions with nanoparticles. Silks from the control samples (devoid of nanoparticles in their feed) had high diameter fibres and are with low $$R_{\mathrm{q}}$$ values and silk yield. However, nanoparticle supplementation to the silkworm’s diet resulted in low diameter silk fibres with varying roughnessess and with improved silk yield for the tested doses.

“Mechanically prepared copper surface in oxidizing and non-oxidizing conditions”

In the present work surface roughness of copper samples after mechanical surface preparation processes (polishing, grinding, sand-blasting) and after exposure in non-oxidizing (high purity argon) and oxidizing (air) conditions at 700 and 750 °C have been evaluated by contact profilometer and by fractal analysis. Quantitative description of surfaces that are hidden from the sight of conventional methods is possible by fractal analysis, e.g. in the present work, the roughness of Cu2O/Cu boundary has been evaluated under oxide layer. It has been pointed out, that in both oxidizing and non-oxidizing conditions initial surface roughness of copper is affected by annealing at high temperature: at 700 °C surface roughness of polished and ground samples increased but at 750 °C decreased in comparison to surface roughness prior to heat treatment. For sand-blasted samples in both oxidizing and non-oxidizing conditions the lowest values of surface roughness parameters were obtained at 750 °C. It is then concluded that two phenomena are responsible for such effect: chemical reaction between copper and oxygen and surface diffusion of copper due to high temperature of annealing.

Influence of the Ball Vibrorolling Parameters on the Surface Roughness and on the Superficial Layer Hardness

The vibroburnishing is a process of surface plastic deforming applied to parts made of metallic materials to diminish the surface roughness, to increase the microhardness of the superficial layer, to generate internal stresses more convenient in certain service conditions of the parts. Practically, the ball vibrorolling process appeared as a result of including a vibratory motion. A ball is used as a deformation tool, as in the case of the more known process of burnishing. The analysis of the vibrorolling process showed that the simplest and the most accessible way of changing the process results could be based by considering the workpiece peripheral rotation speed and the longitudinal feed, respectively. An experimental research was proposed and performed to establish some empirical mathematical models that highlight the influence exerted by the workpiece peripheral rotation speed and by the longitudinal feed on the values of theRasurface roughness parameter and on the thickness of the hardened surface layer at the ball vibrorolling of the external cylindrical surfaces. The investigation considered also the influence of the distance from the test sample surface on the variation of the Vickers microhardness in the test sample superficial layer.

Hydrophobicity, Freezing Delay, and Morphology of Laser-Treated Aluminum Surfaces.

Until recently, superhydrophobicity was considered as a hint to predict surface icephobicity, an association of concepts that is by no means universal and that has been proven to depend on different experimental factors and material properties, including the actual morphology and chemical state of surfaces. This work presents a systematic study of the wetting and freezing properties of aluminum Al6061, a common material widely used in aviation, after being subjected to nanosecond pulsed IR laser treatments to modify its surface roughness and morphology. All treated samples, independent of their surface finishing state, presented initially an unstable hydrophilic wetting behavior that naturally evolved with time to reach hydrophobicity or even superhydrophobicity. To stabilize the surface state and to bestow the samples with a permanent and stable hydrophobic character, laser-treated surfaces were covered with a thin layer of CF x prepared by plasma-enhanced chemical vapor deposition. A systematic comparison between freezing delay (FD) and wetting properties of water droplets onto these plasma-/polymer-modified laser-treated surfaces that, under conditions where a heterogeneous nucleation mechanism prevails, surface morphology rather than the actual value of the surface roughness parameter the key feature for long FD times. In particular, it is found that surface morphologies rendering a Cassie-Baxter wetting regime longer FDs than those characterized by a Wenzel-like wetting state. It is that laser treatment, with or without additional coverage with thin CF x coatings, affects wetting and ice formation behaviors and might be an efficient procedure to mitigate icing problems on metal surfaces.

РЕГЛАМЕНТАЦИЯ ПАРАМЕТРОВ ШЕРОХОВАТОСТИ ФУНКЦИОНАЛЬНЫХ ПОВЕРХНОСТЕЙ ДЕТАЛЕЙ МАШИН В ТЕХНОЛОГИЧЕСКОЙ ДОКУМЕНТАЦИИ

On the basis of the probability theory approach to the formation of surface roughness parameters in machinery during machining there is offered an algorithmic solution of an urgent problem of the regulations of roughness parameters for machinery functional surfaces in technological documentation. The algorithmic solutions for the following parameter versions are developed (RSS 2.309-73): the highest value; the smallest value; a value range; a rated value with ultimate deviations; an indication of two and more parameters. The theoretical investigation results may serve as a starting point for the further development of theory and practice for the technological support of roughness parameters in machinery functional surfaces with the required reliability. 
 Foe a wide actual realization of investigation results the solution of a number of problems is needed: 1) the development of standards or guide information on the regulations in technological documentation of required technological values of roughness parameters; 2) the further development of investigations in the field of technological support reliability of quality parame-ters (including roughness) of blank surfaces in the course of machining in technologically flexible systems.

Correlations development for Nusselt number and friction factor in a dimpled surface heat exchanger tube

ABSTRACTThe present experimental investigation is focused on the study of heat transfer and pressure drop of heat exchanger tube fitted with dimpled ribs on the inner wall. The effect of geometrical parameters, predominantly the streamwise spacing, spanwise spacing, and dimpled depth to print diameter has been investigated. The heat exchanger tube has streamwise spacing () in range of 15–35, spanwise spacing () in range of 15–35, ratio of dimpled depth to print diameter () of 0.5–1.5, and Reynolds number () ranges from 5,000 to 27,000. Experimental results show that the heat transfer and thermal hydraulic performance enhances by 4.19 times and 2.53 times, respectively, for of of 15, of 15, and of 1.0. The experimental data collected are utilized for the development of the statistical correlations for and for selected values of roughness parameters and flow Reynolds number.

Research of Thermoplastics Turning after Workpiece Ultrasonic Treatment

The results of experimental studies of a new method for turning billets from thermoplastic polymers such as caprolon and fluoroplastic are presented. The technical essence of the method is in workpiece advanced processing by ultrasonic vibrations using preliminary machining. Experimental studies were carried out on a lathe which is equipped with an ultrasonic oscillatory system. Roughness level profilograms of the caprolon and fluoroplastic treated surfaces are used for visual and operational control of the turning process. The results of the experimental verification of the developed method confirmed the expediency of its implementation since the use of advanced ultrasonic treatment during turning of thermoplastics leads to a decrease in the roughness level of the treated surface of the part as evidenced by the values ​​of roughness parameters and the type of chips obtained.