Dependence Of Roughness Research Articles

Experimental testing of roughness parameters during vibratory lapping of flat surfaces

The basic design parameters and operational conditions of an enhanced vibratory lapping machine are considered. The main purpose of the research is to define the influence of different machining regimes on the roughness parameters of flat surfaces of parts made of C22 steel. The experiments are carried out at different controllable conditions of the vibratory lapping process: amplitudes of vibrations of the upper lap, forced frequencies, machining durations, and lapping paste types. The obtained results are shown in the form of bar charts describing the dependencies of the surface roughness on the machining conditions mentioned above. The major scientific novelty consists in the further development of the technologies of lapping and polishing of flat surfaces using vibratory machines with an electromagnetic drive. The presented research can be used by engineers and technologists while improving existent designs of vibratory lapping-polishing machines, as well as enhancing the corresponding machining processes.

Effect of plasticizers on the rheological properties of xanthan gum - starch biodegradable films

The effect of plasticizers, namely glycerol, sorbitol, and citric acid, on the structural and mechanical properties of biodegradable films obtained from xanthan gum (XG) and starch was studied. The plasticizing effect of glycerol, sorbitol, and citric acid on XG-starch films is justified by the destruction of intermolecular contacts between starch and XG macromolecules and the redistribution of hydrogen bonds in the system as a result of the hydrotropic action of plasticizer molecules. The use of glycerol proved to be the most effective for regulating the deformation of films, while the use of sorbitol to preserve strength. The dependence of the film roughness on the type and concentration of plasticizers was characterized. The smallest values of protrusions on the surface of XG-starch films were found in the presence of sorbitol. Considering the effect of the concentration of plasticizers on the stickiness of the surface of XG-starch films and their structural and mechanical properties, 1.5 % concentration of glycerol, sorbitol and citric acid was determined as optimal.

From creep to flow: Granular materials under cyclic shear

When unperturbed, granular materials form stable structures that resemble the ones of other amorphous solids like metallic or colloidal glasses. Whether or not granular materials under shear have an elastic response is not known, and also the influence of particle surface roughness on the yielding transition has so far remained elusive. Here we use X-ray tomography to determine the three-dimensional microscopic dynamics of two granular systems that have different roughness and that are driven by cyclic shear. Both systems, and for all shear amplitudes Γ considered, show a cross-over from creep to diffusive dynamics, indicating that rough granular materials have no elastic response and always yield, in stark contrast to simple glasses. For the system with small roughness, we observe a clear dynamic change at Γ ≈ 0.1, accompanied by a pronounced slowing down and dynamical heterogeneity. For the large roughness system, the dynamics evolves instead continuously as a function of Γ. We rationalize this roughness dependence using the potential energy landscape of the systems: The roughness induces to this landscape a micro-corrugation with a new length scale, whose ratio over the particle size is the relevant parameter. Our results reveal the unexpected richness in relaxation mechanisms for real granular materials.

Modeling Form Roughness Induced by Tidal Sand Waves

AbstractTide‐dominated sandy shelf seas, such as the Dutch North Sea, are covered by sand waves. Yet, basin‐scale hydrodynamic models do not include any sand wave information because their grid sizes are too coarse to resolve sand waves individually. We explore the possibility of parametrizing the effects of sand waves on the larger‐scale tidal flow by means of a form roughness. Specifically, our aim is to see to what extent the flow over a sand wave field can be reproduced by that over a flat seabed with an increased effective roughness (accounting for both grain and form roughness). To do so, we use two process‐based hydrodynamic models: a second order perturbation approach, and Delft3D. Both models demonstrate that the presence of sand waves causes amplitude decrease and phase shift of the tidal flow. We explore the dependencies of form roughness on different sand wave characteristics (wavelength, height and asymmetry). Shorter and higher sand waves cause a higher form roughness, while our analysis does not reveal any dependency on sand wave asymmetry. Notably, the consideration of a tidal flow, characterized by several tidal constituents, each represented by an amplitude and a phase, results in a more complex form roughness analysis than in a fluvial setting, where the flow is unidirectional and steady. We thus obtain an amplitude‐based form roughness and a phase‐based form roughness, each yielding a different value, yet displaying the same qualitative dependencies.

Influence of chemistry and surface roughness of various thermal barrier coatings on the wettability of molten sand

High temperature wettability experiments were carried out to investigate how chemistry and surface roughness affect wetting characteristics of molten sand several promising thermal/environmental barrier coatings. Contact angle experiments were performed on varying as-sprayed and polished yttria-stabilized zirconia (YSZ), rare-earth oxide-YSZ (REO-YSZ), and rare-earth silicate coatings subjected to molten synthetic sand at 1260 °C. The results showed that the spreading rate of molten sand was higher on silicate-based environmental barrier coatings (~60°/min) than on Zr-based thermal barrier coatings (~25°/min). Increased surface roughness had opposite effects on the wettability depending on the reactivity of the coatings. Wettability decreased on coatings such as YSZ (which did not react with sand) but increased for REO-YSZ coatings (which formed reaction products with sand). It was found that while the REO-YSZ coatings were able to promote formation of the apatite that performed as a sealing layer to reduce further infiltration, molten sand wetting increased. YSZ was found to have greater wetting resistance in the roughened state while the REO-YSZ coatings had greater wetting resistance in the polished state. Surface energy, microstructure, and molten sand penetration also play a key role in the wetting kinetics and are discussed. This work reveals the dependency of chemistry and surface roughness on influencing the “sandphobicity” (analogous to hydrophobicity) of a material and provides insights for optimizing these variables to realize more “sandphobic” coatings.

Evolution of the mixed mode FPZ and fracture roughness of Beishan granite after coupled thermo-hydro-mechanical treatment

Deep surrounding rocks contain a network of longitudinally intersecting fissures. Exploration of their fracture process zone (FPZ) size evolution during mixed loading and fracture surface roughness after failure has always been a hot topic, especially for coupled thermo–hydro–mechanical (THM) treatment. This study takes Beishan granite as the research object. The fracture surface roughness and FPZ length were obtained using Grasselli statistical and mixed strain–displacement methods. Finally, an electron microscope was employed to observe the fracture surface after failure at different temperatures and loading angles. Results reveal a notable temperature and load dependence of the fracture surface roughness and FPZ length evolution. In the low-temperature stage (25°C–300°C), the mineral primarily exhibited transgranular fractures and the average fracture surface roughness showed a slightly decrease with increasing temperature. In the high-temperature stage (500℃–650℃), the degree of internal damage to the prepared specimens substantially increased, with intergranular fractures being the dominant fracture mode, and rapid roughness growth occurred. Under the same temperature condition, the roughness value was in the order of mode I > mixed mode > mode II. The FPZ length increased, stabilized, and decreased as the load increased. In the low-temperature stage, the FPZ length reached its maximum value at the maximum load, whereas in the high-temperature stage, the FPZ length was fully developed before the peak load. Under the same loading angle condition, the FPZ lengths corresponding to the three loading modes followed the order of mode I < mixed mode < mode II.

An incremental approach for calculating dominance-based rough set dependency

An incremental approach for calculating dominance-based rough set dependency

Impact of air jet impingement technology on the strength of tissue paper

Impinging air jets can be used to dewater, heat, and dry the web of tissue paper. High velocities of the air jets degrade the paper, and appropriate adjustments to the jet velocity and the distance of the nozzle from the surface of the wet web are crucial to obtain the highest quality product. This work investigated the correlation between the velocity of the air jet and the strength of paper subjected to the impingement method. Papers with an initial moisture content of 20% and various pulp mixes were tested, and the physical properties of papers were explored. After impinging an air jet, different tensile strength limits were obtained in the machine and cross directions. The paper had lower apparent density and higher roughness compared to classical pressing. The dependence of tensile strength and roughness on the fibers composition also was determined. Increasing the amount of eucalyptus fibers in impingement dewatered paper resulted in a decrease in its tensile strength and roughness. The value of elongation before breaking was the highest for softwood papers after the impingement method. The maximum velocity of an air jet that can be used to dewater or dry paper without the risk of damage to the papers was determined.

The choice of the magnetic abrasive action method for processing cutting plates

The existing methods of processing workpieces between two pole tips are described in detail. It is proved that the addition of movements in the process of magnetic abrasive treatment significantly increases the production capabilities, and the plates are obtained with a radius specified by technologists and other geometric parameters. The developed method and device make it possible to process plates on different machines and at different technological parameters. Graphs of the dependence of roughness, material removal and plate radius on processing parameters are described in detail. In conclusion, conclusions are drawn about the viability of the method, as well as the prospects for the development of the magnetic abrasive treatment method. Key words. Operating surfaces, regular microgeometry, material removal per unit area, magnetic abrasive polishing, rounding of the tool cutting edge, two-pole tips

Single-cell fluid-based force spectroscopy reveals near lipid size nano-topography effects on neural cell adhesion.

Nano-roughness has shown great potential in enhancing high-fidelity electrogenic cell interfaces, owing to its characteristic topography comparable to proteins and lipids, which influences a wide range of cellular mechanical responses. Gaining a comprehensive understanding of how cells respond to nano-roughness at the single-cell level is not only imperative for implanted devices but also essential for tissue regeneration and interaction with complex biomaterial surfaces. In this study, we quantify cell adhesion and biomechanics of single cells to nano-roughened surfaces by measuring neural cell adhesion and biomechanics via fluidic-based single-cell force spectroscopy (SCFS). For this, we introduce nanoscale topographical features on polyimide (PI) surfaces achieving roughness up to 25 nm without chemical modifications. Initial adhesion experiments show cell-specific response to nano-roughness for neuroblastoma cells (SH-SY5Y) compared to human astrocytes (NHA) around 15 and 20 nm surface roughness. In addition, our SCFS measurements revealed a remarkable 2.5-fold increase in adhesion forces (150-164 nN) for SH-SY5Y cells cultured on roughened PI (rPI) surfaces compared to smooth surfaces (60-107 nN). Our data also shows that cells can distinguish changes in nano-roughness as small 2 nm (close to the diameter of a single lipid) and show roughness dependence adhesion while favoring 15 nm. Notably, this enhanced adhesion is accompanied by increased cell elongation upon cell detachment without any significant differences in cell area spreading. The study provides valuable insights into the interplay between nano-topography and cellular responses and offers practical implications for designing biomaterial surfaces with enhanced cellular interactions.

ДОСЛІДЖЕННЯ ШОРСТКОСТІ ПОВЕРХНІ ПРИ ОБТОЧУВАННІ ХРОМОМОЛІБДЕНОВОЇ СТАЛІ

Surface roughness is one of the parameters of product quality, that’s why the research of cutting mode impact on surface roughness is a current topic. The diversity of cutting tools and materials to be worked leads to the need for more detailed study of the impact of cutting modes on surface roughness.Previous researches have established that the radius of curvatureof cutting tool and the cutter feed have an impact on surface roughness. There are also studies for assessing cutting speed and cutting depth effects on surface roughness. But these studies are not complete and exhaustive, because they have been done for selected materials, cutting tools and cutting modes.The aim of the research described in the article is a scientific inquiry of cutting mode impact on surface roughness in turning of chromium-molybdenum steel 38ХМand the search for optimal cutting modes for this steel.The mathematical relationship between surface roughness and cutter feed, cutting depth, cutting speed was written in the form of power function. The range of variation was chosen. Regression coefficients were defined on the methodology of full factor experiment of type 23. The constructed mathematical model has been checked for adequacy. The equation of surface roughness dependence on cutting mode in turning of 38ХМsteel was obtained.Finding the best possible combinations of cutter feed, cutting depth, cutting speed values for turning of 38ХМsteel was undertaken using the Taguchi method. It was based on the search for technological modes in which the evaluated quality parameter is least affected by uncontrolled factors.As a result of the research it is established that cutting speed and cutting feed have the greatest impact on surface rough-ness. It is also shown that cutting depth has a negligible impact on surface roughness. It is proved that the machining processed at small cutting depthand small feed and large cutting speed is most appropriate. The optimal cutting modes for turning, providing minimal surface roughness are determined.Thus, the complex use of full factor experiment method and the Taguchi method made it possible not only to obtain the equation for the dependence, but also to determine optimal cutting modes.

Noise-aware and correlation analysis-based for fuzzy-rough feature selection

Feature selection has gained significant attention, with a focus on removing redundant or irrelevant features to improve subsequent machine learning tasks. The fuzzy rough set is extensively utilized for feature selection because of its ability to manage uncertainty. The fuzzy dependency-based approach represents an effective branch within the domain of fuzzy rough set models. However, it has been revealed that fuzzy dependency function is not robust to noise data while the noise objects often occur. Furthermore, as the size of dataset increases, the computational complexity of evaluating metrics also tends to increase due to potentially unnecessary computational effort. Hence, to address both of these research issues simultaneously, we propose a fuzzy rough correlation-based feature selection algorithm, denoted as FRCB. The introduction of neighborhood radius constraints and granularity conditions aims to interpret and mitigate the impact of noisy data by partitioning objects into a Core-Boundary-Outlier structure. A more robust hybrid fuzzy relation and correlation-based fuzzy rough dependency is proposed by considering the representativeness and attractiveness of the core to other objects within the internal class, as well as the impacts on other objects in external classes. To minimize processing overhead and time complexity, redundant features are identified through correlation analysis, which involves evaluating, ranking, and grouping before proceeding to the next iteration. The experiments were conducted using eleven datasets. The analysis of the noise curves and the raw data curve indicates that the proposed correlation-based fuzzy rough dependency is more robust than other benchmarking methods. Moreover, the results of the classification and running time comparisons indicate that the FRCB algorithm proposed in this study exhibits superior performance compared to the baseline methods.

Investigation of the Change in Roughness and Microhardness during Laser Surface Texturing of Copper Samples by Changing the Process Parameters

The aim of this research is to achieve a high-quality and long-lasting laser marking of ammunition, which is of interest to the defense industry. The study is about the effects of speed, raster pitch and power on the roughness and microhardness of the marked areas of copper samples. The experiments were carried out with a fiber laser and a copper bromide laser—modern lasers widely used in industrial production. Laser power, scan speed and raster step were varied to determine their effects on the resulting microhardness and surface roughness. The lasers operate in different wavelength ranges, with the optical laser operating at 1064 nm in the near-infrared region and the copper bromide laser at 511 nm and 578 nm in the visible region, allowing the influence of wavelengths on the process to be investigated. The roughness and microhardness velocity dependence for three powers and two pulse durations for the fiber laser were obtained from the experimental data. The dependence of roughness and microhardness on the raster step for both types of lasers was also demonstrated.

Size and pressure dependence lattice thermal conductivity of Wurtzite GaN nanowires

The size and pressure effect on lattice thermal conductivity (LTC) of Wurtzite GaN NWs with diameters of 97, 100, 126, and 160 nm in the temperature range (2–350) K fitted to those reported experimental data. The investigations were based on the Debye-Callaway model along with the Clapeyron and Murnaghan equations, for both longitudinal and transverse modes of phonons. by considering in the calculations, the nanosized dependence of melting temperature, lattice volume, Debye temperature, and group velocity. Nanosized melting temperature is used to calculate its related parameters of melting enthalpy, melting entropy, and surface energy. In this work, the nanosized dependence relation for the Gruneisen parameter gives values of 0.14475 for 160 nm and increases to 0.14535 for 97 nm. While its modification due to the applied pressure reduces its value. The relations are obtained for the nanosized dependence of surface roughness, Casimir length, dislocation concentration and lattice scattering factor, enabling this model to obtain LTC free from fitting parameters. The model was then applied successfully on 50 and 30 nm NWs diameter for this binary semiconductor.

Influence of Surface Preparation on the Microstructure and Mechanical Properties of Cold-Sprayed Nickel Coatings on Al 7075 Alloy

This work presents the effect of surface roughness (Al 7075) on the microstructure and mechanical properties of cold-sprayed nickel coatings. Coating analysis included substrate surfaces and coating geometry, microstructure characterization, microhardness, nanohardness, elastic modulus, and adhesion. The results show that the surface preparation had a significant effect on coating adhesion and microstructure. The coating deposited at the highest gas temperature revealed a dense microstructure, showing very good adhesion of the impacting powder particles to the substrate and good bonding between deposited layers. The Ni grains with different shapes (elongated, equiaxed) and sizes of a few dozen to several hundred nanometres were present in the splats. An increase in temperature caused significant growth in coating thickness as a result of the powder grains’ higher velocity. Moreover, higher gas temperature resulted in the enhancement of micro- and nanohardness, elastic modulus, and adhesion. The adhesive bond strength of Ni coatings in the tested temperature ranges from 500 °C to 800 °C increased with the increase in the surface roughness of the substrate. For the Al 7075 coarse grit-blasted (CG) substrate with the highest roughness, the adhesion reached the highest value of 44.6 MPa when the working gas was at a temperature of 800 °C. There were no distinct dependencies of surface roughness and thickness on the mechanical properties of the cold-sprayed nickel coating.

ANALYSING THE INFLUENCE OF TECHNOLOGICAL PARAMETERS ON THE PROCESS OF LASER MARKING OF SURFACE OF ANODISED ALUMINIUM SAMPLES

The requirements for marking in terms of contrast and durability are constantly increasing. In order to meet all these challenges, it is necessary to carry out research leading to the optimisation and increase in efficiency of the technological process of laser marking. In the case of aluminium, the contrast and durability of the marking depend on the values of the laser marking parameters. In order to determine the optimal laser marking method, experimental studies have been carried out, controlling the power, speed, frequency, pulse duration and line raster step for a specific anodised aluminium. The studies carried out were analysed and subsequently optimized to obtain a contrast marking. A Rofin PowerLine F 20 Varia fiber laser system and aluminium alloy 1050 with anodised surface were used for the research. The surface changes after the laser treatment were analysed using a laser scanning microscope and contrast determination method. The dependence of contrast and roughness on speed, power, frequency and raster step was analysed. Comparative plots of contrast and roughness variations versus laser marking technological parameters were constructed.

АНАЛИЗ ВЛИЯНИЯ ОТНОСИТЕЛЬНОЙ ШЕРОХОВАТОСТИ ТРУБОПРОВОДОВ НА ПОТЕРИ НАПОРА

The dependence of the relative roughness of pipelines on pressure losses at different flow rates of the liquid medium is studied

Regional Variations in the Spreading‐Rate Dependence of Abyssal Hill Roughness as Indicators of Mantle Heterogeneity

AbstractAbyssal hills are potential proxy records of mid‐ocean ridge faulting and volcanism, as well as the spreading rates and mantle properties that influence these processes. Satellite gravity‐based global prediction of abyssal hill root‐mean‐square (RMS) heights could provide such a proxy, but are broadly influenced off‐axis by pelagic sediment cover, which can lower their values by preferentially filling lows. Here I formulate a sediment‐corrected RMS height prediction by estimating an empirical relationship between mean RMS and sediment thickness as a function of spreading rate. I utilize these values to investigate regional variations in the spreading‐rate dependence of mean RMS across eight regions world‐wide, focusing on half spreading rates &lt;40 mm/yr where spreading rate dependence is strongest. I find that regional variations in this relationship are significant, likely indicating heterogeneity in mantle properties between the different regions.

Frictional power dissipation in a seismic ancient fault

The frictional power per unit area Q˙ (product of frictional traction τ and slip rate u˙ in MW m−2) dissipated during earthquakes triggers fault dynamic weakening mechanisms that control rupture nucleation, propagation and arrest. Although of great relevance in earthquake mechanics, Q˙ cannot, with rare exceptions, be determined by geophysical methods. Here we exploit theoretical, experimental and geological constraints to estimate Q˙ dissipated on a fault patch exhumed from 7-9 km depth. According to theoretical models, in polymineralic, silicate rocks the amplitude (< 1 mm) of the grain-scale roughness of the boundary between frictional melt (pseudotachylyte) and host rock decreases with increasing Q˙. The dependence of grain-scale roughness with Q˙ is due to differential melt front migration in the host rock minerals. This dependence is confirmed by friction experiments reproducing seismic slip where pseudotachylytes were produced by shearing tonalite at Q˙ ranging from 5 to 25 MW m−2. In natural pseudotachylytes across tonalites, the grain-scale roughness broadly decreases from extensional to compressional fault domains where lower and higher Q˙ are expected, respectively. Analysis of the natural dataset calibrated by experiments yields Q˙ values in the range of 4-60 MW m−2 (16 MW m−2 average value). These values, estimated in small fault patches, are at the lower end of broad estimates of Q˙ (3-300 MW m−2) obtained from frictional tractions (30-300 MPa) and fault slip rates (0.1-1 m/s) assumed as typical of upper crustal earthquakes.

ИССЛЕДОВАНИЕ ЗАКОНОМЕРНОСТЕЙ ФОРМИРОВАНИЯ МИКРОПРОФИЛЯ ОБРАБОТАННОЙ ПОВЕРХНОСТИ ПРИ ХОНИНГОВАНИИ С ПРЕДВАРИТЕЛЬНОЙ КРИОГЕННОЙ ОБРАБОТКОЙ

This article is devoted to the study of the regularities of the formation of the microprofile of the treated surface during honing with preliminary cryogenic treatment. The dependence of surface roughness on processing modes during honing with preliminary cryogenic treatment of products from low-carbon steels has been studied. Mathematical models of these processes in the form of regression equations are obtained. Empirical curves of dependencies of the roughness parameter Ra are constructed using the Microsoft Excel 9.0 application package and the MathCAD 15.0 package.