Roughness Profile Research Articles

Microstructure-Sensitive modeling of surface roughness and notch effects on extreme value fatigue response

Fatigue life knockdown due to surface roughness induces local stress concentrations. Physical fatigue experiments are crucial to qualify materials for use but are limited in their capability to examine the mechanisms underlying the fatigue crack formation driving force due to these stress concentrations. Microstructure-sensitive computational models can aid in this regard and are employed in this work to examine the effects of surface roughness in Al 7075-T6. Digital microstructure models are subjected to crystal plasticity finite element method (CPFEM) simulations to examine the combined effects of microstructure and grain scale asperities on the driving force for fatigue crack formation. Following elastic–plastic shakedown, mesoscale volume-averaged fatigue indicator parameters (FIPs) are computed within fatigue damage process zones of grains. An increase in the intensity of realistic surface roughness profiles corresponds accordingly to larger FIPs but it is difficult to precisely interpret the mechanisms and effects of this intensification. We thus parametrically investigate surface asperities that couple with microstructure and lack of constraint on slip at the free surface to describe microstructure-sensitive surface roughness knockdown effects on fatigue resistance. The depth of a single valley (i.e., notch) due to surface roughness is found to be more detrimental to fatigue resistance than the radius (i.e., notch width, not to be confused with notch acuity). We also find that different crystallographic textures, grain morphologies, and number of sampled grains have a limited effect on the depth of influence of these notches.

Characterization of the topography generated by low plasticity burnishing using advanced techniques

This work investigates the surface topography of AISI 304 austenitic stainless steel after low plasticity burnishing through the evaluation of the average surface roughness (Ra), surface texture direction, areal power spectral density (APSD), scale-sensitive fractal analysis and continuous wavelet transform (CWT). The reason for adopting these approaches resides in the fact that traditional amplitude profile parameters neglect dynamic aspects of the process and geometric features of the burnished surface. The direction, periodicity and anisotropy of the surface texture were influenced by number of passes and burnishing speed and, in general, less severe plastic strain conditions tended to produce surfaces with strongly anisotropic characteristics, preferred direction of motifs, with power spectrum indicating a well-defined spatial frequency of peaks, lower fractal complexity and uniform profile distribution. The increase in surface strain severity produced surfaces with more diffuse directional characteristics, which tended to present surface isotropy, higher spatial frequency dispersion of the peaks and higher fractal complexity. Furthermore, the transition from an anisotropic to an isotropic surface can occur without changes in the average surface roughness. The continuous wavelet transforms analysis indicated a dynamic variation on the surface plastic strain when burnishing. The intermediary burnishing speed induced a strong disturbance with loss of periodicity of the roughness profile, resulting in a remarkable influence on the roughness profile in small scales. The increase in number of passes elevated the plastic strain severity, affecting the surface macrogeometric profile. The isotropic surface promoted a less severe stress concentration, reducing the tensile stresses and retarding crack nucleation, thus increasing the fatigue considerably.

Study of the Influence of the Surface Roughness of Knitted Fabrics from Natural Fibres on the Light Fastness of Their Colours

The article examines the influence of the surface properties of knitted fabrics from cotton and wool of various knitted structures on the light fastness of their colours. The surface properties of knitted fabrics of single plain, 1×1 rib and French piqué knitted structures were evaluated by determining their roughness using a non-contact optical method for processing digital images of the knitted fabric’s surface. The roughness profiles of the corresponding knitted fabric samples were obtained, and the main indicators of surface roughness were calculated: the profile height at ten points Rz and the arithmetic mean profile deviation Ra . Cotton knitted fabrics were dyed with the Bezaktiv Cosmos dye brand, which are bifunctional reactive dyes with monochlorotriazine / vinyl sulfone active groups, and wool knitted fabrics were dyed with acid dyes. The light fastness of the samples was evaluated after exposure to the Light Fastness Tester (Mercury-Tungsten Lamp) RF 1201 BS (REFOND) with a PCE-TCR 200 colorimeter. Colour measurements were averaged for each sample. Total colour difference (dE) was measured on the dyed cotton knitted fabrics samples after light exposure. According to the obtained roughness profiles of cotton and wool knitted fabrics, it can be concluded that the studied knitted fabrics are characterized by different roughness, which depends on their knitted structures. At the same time, a relationship was found between an increase in the roughness of knitted fabrics and the photodestruction of colours by reactive and acid dyes on cotton and wool knitted fabrics, respectively. The results show that the surface structure of knitted fabrics, that is the knitted structure, impacts the process of colour photodestruction and that the amount of dye that has undergone photodestruction increases with the increasing surface roughness of the knitted fabric.

Characterization of diffractive relief structures over large areas by stitching interference microscopic topography

The development of diffractive optical elements (DOEs)enables fascinatingly compact design and chromatic aberration correction. Fabrication errors of DOEs include periodic pattern error, relief profile error and roughness which affect imaging quality and diffraction efficiency. Characterization of the DOE requires thus multi-scale measurement of the surface topography over the full aperture of 10 mm scale. This paper presents a method based on the white light interferometry in combination of subaperture stitching. Firstly, the principle of measurement and subaperture layout design is introduced. The measuring system is easily set up by integrating a scanning platform with the interference microscope. Subaperture stitching algorithm is developed based on the surface height change related to the scanning motion error. The slope of the relief profile is used to model the deviations of overlapping point pairs induced by lateral shift and rotation. Finally, the topography and fabrication error of a Fresnel lens surface are experimentally obtained and characterized over the full aperture through stitching of totally 67 subapertures.

Artificially roughened solar air heating technology – A comprehensive review

• Various artificial roughness geometries used by various researchers have been reported in current review article. • Nu and f have been calculated for the twelve roughness geometries, and a comparison has been made to opt for the best roughness among them. • At Re = 24,000 perforated V-shape baffles gave the highest Nu compare to other roughness geometries, it has Nu 6.5 times higher than the smooth SAH. • Similarly, at Re = 24,000f for protrusion roughness has been found to have the lowest value of f compared to the other roughness geometries. For various heating applications like space heating, timber seasoning, food drying, HVAC processes, water desalination processes, etc., where a low to medium heating source is required, the solar air heater is the most promising device to supply the appropriate heated working fluid with least possible cost of heating processes. Over the years, the improvement in the performance of the SHAs has become a fascinating area of research. The thermal efficiency of SAH is low because the boundary layer generation on the absorber plate causes resistance to heat transmission. Artificial roughness is the most efficient technique to break the laminar boundary layer, hence improving heat transmission. In this paper, various artificial roughness geometries used by various researchers have been reported. Based on the correlations and optimum parameters for the respective roughness provided by the respective authors, Nu, f, and thermohydraulic performance parameter have been calculated for the eleven roughness geometries using Microsoft excel 2021, and a comparison has been made to opt for the best roughness among them. At Re = 24,000, internal conical ring obstacles with impinging jets give the highest Nu compared to other roughness geometries; which has Nu 4.89 times higher than the smooth SAH. Similarly, at Re = 24,000, f for discrete reverse NACA 0040 profile roughness has been found to have the lowest value of f compared to the other roughness geometries, and it has f as 1.32 times higher compared to the smooth SAH. Thermohydraulic performance parameter ( η ) was found highest for perforated conical disc inserts with helical corrugations roughness at R e < 16000 and lowest for perforated delta roughness at Re > 16000 . The thermohydraulic performance parameter ( η ) has a maximum value of 2.440 for a hybrid broken arc with staggered ribs roughness at Re = 24,000. It has been noted that tremendous numerical and experimental work has been reported in the literature. In this study, key findings are discussed, the influence of the various roughness parameters on heat transmission and pressure drop are summarized, and recommendations are also provided for future research.

Surface Characterization of Lüders Band on NiTi Shape Memory Alloy

The tensile deformation of NiTi alloy can proceeds in either homogeneous manner, or localized deformation via formation and propagation of macroscopic shear bands, that is commonly known as Lüders-like deformation. The high deformation strain within the localized deformed regions can result in the changes of surface characteristics of NiTi specimen. This paper studies the surface roughening effect associated with Lüders-like deformation of martensitic NiTi alloy, via surface characterization of polished surface and localized deformed region that consists of Lüders bands on tensile specimens, respectively. The surface roughness profile and roughness parameters of surface with Lüders bands are significantly different and higher as compared to the polished surface.

Effect of the Deposition Time on the Structural, 3D Vertical Growth, and Electrical Conductivity Properties of Electrodeposited Anatase-Rutile Nanostructured Thin Films.

TiO2 time-dependent electrodeposited thin films were synthesized using an electrophoretic apparatus. The XRD analysis revealed that the films could exhibit a crystalline structure composed of ~81% anatase and ~6% rutile after 10 s of deposition, with crystallite size of 15 nm. AFM 3D maps showed that the surfaces obtained between 2 and 10 s of deposition exhibit strong topographical irregularities with long-range and short-range correlations being observed in different surface regions, a trend also observed by the Minkowski functionals. The height-based ISO, as well as specific surface microtexture parameters, showed an overall decrease from 2 to 10 s of deposition, showing a subtle decrease in the vertical growth of the films. The surfaces were also mapped to have low spatial dominant frequencies, which is associated with the similar roughness profile of the films, despite the overall difference in vertical growth observed. The electrical conductivity measurements showed that despite the decrease in topographical roughness, the films acquired a thickness capable of making them increasingly insulating from 2 to 10 s of deposition. Thus, our results prove that the deposition time used during the electrophoretic experiment consistently affects the films’ structure, morphology, and electrical conductivity.

The new method for hydraulic calculations of a district heating (DH) network

How to estimate the exact value of pressure losses within a district heating (DH) network been in service for decades, which a pump at pumping station should compensate to achieve maximum benefits and the lowest costs relative to the scenario of the started process of transition to 4th generation district heating (4GDH)? Geographic Information System (GIS) software Zulu© was used to model a DH network and evaluate how specific location will affect hot water flow rates. Pressure, roughness and hydraulic resistance profiles were plotted using hydraulic optimisation software ZuluThermo©– GIS Zulu© add-in. While the new arrangement does not reduce pressure losses themselves, the corrected arrangement provides economic advantage due to lower operation costs and more stable hydraulic profiles. That means that end sections of DH network between the transmission line and consumers become more effective. By calculating pressure loss and temperature degradation the method also allows to detect an optimum location to connect a new consumer where the minimum modernisation is needed. Working with data-driven network models makes it possible to obtain a lot of positive effects at the same time including the main - the DH utility sells more heat and becomes more profitable as the losses are lower. • To ensure low-temperature energy supply, its consumption for pumping is assessed. • Steady-state calculation method is used to evaluate pressure and flow distribution. • To verify, portable ultrasonic flow rate meter&traditional pressure sensors are used. • Electricity consumption is decreased by 394.74 kW, the saving effect is up to 6%. • Effect is achieved by lowering losses, clarifying friction factor&relative roughness.

Numerical simulation of low reynolds number 2-d rough blade compressor cascade

In this paper, a double-circular-arc cascade was used as the research object to study the effect of roughness on the compressor cascade under the conditions of different incoming attack angles. The Reynolds number of the cascade is 1.5×105 . The profile of the suction surface is changed to simulate the change in surface roughness. A uniformly distributed 238 control points were selected on the suction surface profile of the smooth blade. The 238 points are increased randomly along with the normal phase of the wall, and a smooth curve connects these points to obtain a rough suction surface profile. In this study, numerical simulation methods were used to calculate the cascade flow field under 5 kinds of attack angles and 6 kinds of suction surface roughness (including smooth surface). In this paper, k−ω SST and large eddy simulation were used for numerical simulation calculation with the model respectively. The calculation results show that the effect of roughness on the flow field of the cascade is different under different angles of attack. When 70&lt;ks+&lt;130 the rough suction surface can increase the lift coefficient of the compressor blade.

Recovery of impenetrable rough surface profiles via CNN-based deep learning architecture

ABSTRACT In this paper, a convolutional neural network (CNN)-based deep learning (DL) architecture for the solution of an electromagnetic inverse problem related to imaging of the shape of the perfectly electric conducting (PEC) rough surfaces is addressed. The rough surface is illuminated by a plane wave and scattered field data is obtained synthetically through the numerical solution of surface integral equations. An effective CNN-DL architecture is implemented through the modelling of the rough surface variation in terms of convenient spline type base functions. The algorithm is numerically tested with various scenarios including amplitude only data and shown that it is very effective and useful.

Joint roughness profiling using photogrammetry

We propose an automated camera setup for photogrammetric roughness analysis in the laboratory environment. The developed fast and low-cost automation setup can be very useful for tedious and laborsome manual field logging practices. The photographs are processed in MATLAB to obtain disparity maps. Coding routines for stereo photogrammetry and digital measurements are written in MATLAB. Secondly, 6 effecting factors (projecting an image onto core face, depth of field, brightness, camera-to-object to baseline distance ratio, projected image size, and occlusion) influencing noise in roughness depth maps computed by employing stereo photogrammetry are investigated. After deciding the best values that allow the lowest amount of noise, depth maps of 6 core faces are computed. Using the 3D point cloud generated, roughness profile measurements are made. Then, 8 profile measurements are made for each core face, both manually and digitally. The accuracy of the disparity maps has been verified by comparing 48 joint roughness coefficient (JRC) measurements made manually using a profile gauge. It was proved that surface roughness can be measured very fast in millimetric accuracy with an average root mean square error (RMSE) of 3.50 and mean absolute error (MAE) of 3.02 by the help of the proposed set-up and calibration.

Influence of Shot Peening on the Wear Behaviour of Medium Carbon Steel

Abstract Influence of shot peening on the wear behaviour of medium carbon, C55 steel was experimentally verified. Experimental work included determination of the chemical composition, heat treatment, microstructure evaluation, mechanical properties measurement, shot peening treatment, the magnitude of the compressive residual stresses was evaluated, roughness profiles measurement and finally the friction tests. The results evidence the significant role played by the applied shot peening on wear behaviour of medium carbon steel. An important effect of surface roughness has been demonstrated. The coefficient of friction after shot peening compared to ground surface increased, 1.44 – 1.85 times.

Surface shape reconstruction from phaseless scattered acoustic data using a random forest algorithm.

Recent studies have demonstrated that acoustic waves can be used to reconstruct the roughness profile of a rigid scattering surface. In particular, the use of multiple microphones placed above a rough surface as well as an analytical model based on the linearised Kirchhoff integral equations provides a sufficient base for the inversion algorithm to estimate surface geometrical properties. Prone to fail in the presence of high noise and measurement uncertainties, the analytical approach may not always be suitable in analysing measured scattered acoustic pressure. With the aim to improve the robustness of the surface reconstruction algorithms, here it is proposed to use a data-driven approach through the application of a random forest regression algorithm to reconstruct specific parameters of one-dimensional sinusoidal surfaces from airborne acoustic phase-removed pressure data. The data for the training set are synthetically generated through the application of the Kirchhoff integral in predicting scattered sound, and they are further verified with data produced from laboratory measurements. The surface parameters from the measurement sample were found to be recovered accurately for various receiver combinations and with a wide range of noise levels ranging from 0.1% to 30% of the average scattered acoustical pressure amplitude.

Experimental Investigation on Al 6061 and Al 2024 Aluminium alloys for achieving Surface Roughness using CNC Vertical Face Milling Process

Abstract: The influence of process factors and the integrity of the surface roughness are investigated experimentally in the current study on the metals Al6061 and Al2024. In order to conduct vertical cutting tests for both base alloys, a mixed level L9 orthogonal array is used. An optical emission spectrometer is used to analyse the chemical composition. SEM is used to analyse the microstructure of the materials used to discover tiny inertinitic precipitates in an aluminum matrix using ANOVA Table value. Mild steel was the tool employed, and surface topography and 2D roughness profile data were used to assess the surface integrity of cut surfaces. The experimental trials with various degrees of process parameters, such as Taguchi L9 orthogonal array. In determining surface roughness, speed, feed, and depth of cut are determined to be the most important variables.

Nitrogen Supersaturation into AISI420 Mold for Precise Machining

The plasma nitriding conditions and processing parameters were controlled to attain the high-density nitrogen ion and NH-radical populations and to form the nitrogen supersaturated layer into AISI420 type martensitic stainless steel mold substrate at 673 K for 14.4 ks and 28.8 ks. Thicker nitrided layer than 80 mm was attained for fine machining of the optical diffraction elements onto this nitrided AISI420 mold surface. The average hardness in this nitrogen supersaturated layer reached 1400 HV. After this hardness testing and microstructure analysis, the machinability test was performed to describe the ductile mode cutting behavior of nitrogen-supersaturated work by using the PCD (Poly-Crystalline Diamond)-chip tool. Higher average nitrogen solute content than 4 mass% was responsible for fine turning by PCD-chip and CVD (Chemical Vapor Deposition)-diamond coated cutting tools without any damages and for precisely finishing the mold surface with the lower maximum surface roughness than 10 nm on the machined mold surface. The low roughness and homogeneous machined surface profile proved that the nitrogen supersaturated AISI420 series stainless steel was adaptive as a stamping mold of chalcogenide glasses with high dimensional accuracy and demolding capacity.

Nonequilibrium plastic roughening of metallic glasses yields self-affine topographies with strain-rate and temperature-dependent scaling exponents

We study nonequilibrium roughening during compressive plastic flow of initially flat Cu$_{50}$Zr$_{50}$ metallic glass using large-scale molecular dynamics simulations. Roughness emerges at atomically flat interfaces beyond the yield point of the glass. A self-affine rough topography is imprinted at yield and is reinforced during subsequent deformation. The imprinted topographies have Hurst exponents that decrease with increasing strain-rate and temperature. After yield, the root-mean-square roughness amplitude grows as the square-root of the applied strain with a prefactor that also drops with increasing strain-rate and temperature. Our calculations reveal the emergence of spatial power-law correlations from homogeneous samples during plastic flow with exponents that depend on the rate of deformation and the temperature. The results have implications for interpreting and engineering roughness profiles.

Connectivity of rough contacts in plane and axially symmetric cases

It is customary to assume that a contact of rough elastic solids is always multiply connected, i.e. have regions in it where contact surfaces are apart of each other and contact pressure is zero. The issue of the connectivity in rough elastic contacts has both theoretical and practical interest. In this paper we extend the earlier conducted analysis of rough contacts in plane formulation on the case of axially symmetric rough elastic contacts and compare our findings. The main goal of the paper is to obtain an analytical solution of axially symmetric rough elastic contact and analyze its properties such as contact connectivity and contact pressure smoothness compared to the smoothness of the surface roughness profile. This goal is achieved by using solution expansions in Legendre orthogonal polynomials. In case of a plane contact of rough elastic solids it has been achieved using the solution expansions in Chebyshev orthogonal polynomials. In both axially symmetric and plane cases of rough elastic contacts the ranges of contact parameters for which contacts are singly connected have been determined.

Self-aligned liquid crystals and enhanced electro-optical properties on solution-processed aluminum gallium tin zinc oxide surfaces

An aluminum gallium tin zinc oxide (AlGaSnZnO) film was fabricated by brush coating to create a directional micro/nano structure. Atomic force microscopy was used to observe the physical change in the film surface after brush coating, and the difference in the surface modification according to the curing temperature was analyzed through line profile and surface roughness studies. Changes in the chemical composition of the surface were analyzed through X-ray photoelectron spectroscopy. The liquid crystal (LC) alignment characteristics were analyzed through polarized optical microscopy, pretilt angle, and thermal stability tests. It was confirmed that the orientation direction of LC molecules changed from vertical to horizontal due to the difference in the surface modification at a curing temperature of 180 °C or higher, and stable LC orientation and excellent electro-optical properties were achieved. Brush-coated AlGaSnZnO film is an effective alignment film that controls the LC alignment characteristics with a simple process and can be applied in various fields.

Roughness investigation of steel 316L parts fabricated by Metal Fused Filament Fabrication

Metal Fused Filament Fabrication attracted significant interest in both academia and industry to fabricate net-shape engineering components via low-cost 3D printing technology. However, many fields such as the roughness control and prediction are still unexplored. These aspects are very important to consider especially when the process is used for the fabrication of functional parts: the roughness, in fact, deeply influences the functionality of a component in terms of friction, contact deformation, heat, electric current conduction, etc. Aim of this work is to fulfill the lack of knowledge about the prediction of the obtainable roughness in this process. For the purpose an in-depth analysis of the effect of the processing parameters on surface roughness profiles obtained at green and sintered stages is reported. The experiment is planned using the Design of Experiments technique and the data are collected followed a rigid procedure developed for the scope. The results show that the profiles are markedly affected by the process parameters and depend upon the deposition angles. Green and sintered parts show different behaviors caused by different underling mechanisms. The complexity of the process is highlighted and described by regression models for different deposition angles. The models set allows for a multiple optimization in order to achieve processing parameters combinations able to satisfy desired requirements.

After-Machining Surface Layer of Composite Coatings Obtained by Thermal Spraying

The surface of machine elements is changed to improve their mechanical properties. Ceramic-metal composite coatings are mainly used to increase the durability of machine parts. Therefore, new materials are constantly searched for application in the future development of metal and ceramic composites. The nickel and iron elements are usually used as a base and Al2O3 as tough particles. The welding technology for applying alloy and composite coatings is widely used. The common technology used to apply composite coatings is thermal spraying. It is a simple technology and very useful for the production or regeneration of machines. The surface layer is very rough and porous after applying the coating by thermal spraying. In order to obtain the proper surface quality of alloy and composite coatings, after-machining should be used. Many parts of machines strive to achieve an accurate surface. Therefore, a certain roughness is often required. The arithmetic mean of the ordinates of the surface roughness profile was (Ra = 0.16–1.25 μm). The article presents the influence of finishing on the roughness of the surface layer of the coating. After plastic working and machining, the roughness of the surface layer of the coating was reduced. However, it can be seen that, after plastic working, there is a strengthening of the surface layer of the coating and most of the pores were closed.