Surface Roughness Conditions Research Articles

Analysis and Optimization of Surface Roughness and Microhardness for Roller Burnishing using Response Surface Methodology and Desirability Function Approach on Aluminum 63400

In the present study, response surface methodology (RSM) has been used to optimize roller burnishing process for aluminum alloy 63400 grade. Single roller burnishing tool (carbide) is used to burnish round aluminum alloy. Experiments were performed with Box and Wilson Central Composite Design (CCD). The machining factors controlled during experimentation are speed, feed, force and number of tool passes. The response parameters are surface roughness and microhardness. The most significant control factors on the surface roughness and microhardness were determined by analysis of variance (ANOVA). A controllable process parameter is correlated with surface roughness and microhardness by mathematical model. A quadratic regression analysis is performed to compute the correlation coefficient between the experimental and predicted values. The optimum surface roughness and microhardness foreseen by the model is found to agree well with the results of the experiment. To find the optimum value of both the response, desirability approach was used. The input parameters with most desirability value are selected as the optimum solution. Hence, the most desirable burnished condition desirability value 0.872 is speed 37.9[Formula: see text]m/min, feed 0.5[Formula: see text]mm/rev, force 35.49[Formula: see text]N and number of tool passes four. Surface roughness obtained is 0.524[Formula: see text][Formula: see text] m and microhardness is 125.02[Formula: see text]HV. This is the optimum condition for minimum surface roughness and maximum microhardness. The optimum surface finish and microhardness predicted by the model are found to agree well with the results of the experiment.

Optimization of Cutting Conditions for Surface Roughness in VMC 5-Axis

Vertical machining center (VMC) five-axis is advanced metal cutting process which used tomachine advanced materials for creating parts for industries like die, automotive, aerospace, machinerydesign, etc. Input parameters selection very important in VMC-five axis to obtain better surface finishon milled part and enhanced machining economics. In the present work, experimental analysis has beenplanned to study the significances of milling parameters on quality response, surface roughness (Ra) ofD3 steel. The experiments have been planned on D3 steel in VMC five axis as per Box-Behnken designof response surface methodology (RSM). Modeling and optimization have been done by hybrid RSMand Jaya optimization algorithm. The factor effects on Ra has been studied by analysis of signal-tonoise ratio. The concluding remarks has been drawn from the study

Surface roughness condition of field-aged polymer insulators at different installation area

<span>This paper presents surface degradation assessment based on surface roughness condition for various field-aged high voltage polymer insulators that were installed at different locations. The measurement of arithmetical mean surface roughness is done, and statistical analysis is implemented in this study. Three groups of insulators labeled as 6 years, 12 years, 18 years, and with their respective controlled samples are tested using a surface roughness tester. Data measurements from the testing are analyzed in conjunction with visual observation to investigate an indication of surface degradation within the groups. Further statistical analysis is applied for the comparison of the surface roughness conditions. In order to observe the environmental stress factors that will affect the roughness condition, within the installation area, the virtual three-dimensional mapping program represented the Earth based on satellite imagery is utilized. The correlation analysis on all that three groups has indicated the positive outcomes with the roughness increased with respect to the age of insulator that located in quite similar environmental stress conditions. Regardless of the age of an insulator, the degradation due to surface roughness condition can be used to indicate what levels of environmental stress around the installation area have.</span>

Introduction to this special section: Exploration geophysics in China

China ranks second and third in global oil and natural gas consumption, and fifth and sixth in global oil and natural gas production, respectively ( U.S. EIA, 2018 ). In the past 25 years, China's oil consumption has increased 3.5 times, and natural gas consumption is rising rapidly as well. China is increasing its investment in the petroleum industry, with a goal of significantly expanding domestic oil and gas production. Complex geology, rough surface conditions, and the need to explore deep targets, unconventional resources, and offshore reservoirs pose great challenges to geophysical exploration. Geophysical technologies in China thus have advanced significantly in data acquisition, processing, and interpretation. To demonstrate the development and applications of geophysical technologies in the exploration, development, and production of oil and gas resources, we invited academic and industry experts to present recent studies on exploration geophysics in China.

Atmospheric dry deposition processes of particles on urban and suburban surfaces: Modelling and validation works

Dry deposition process is one of the important pathways for the removal of particles from atmosphere. It is the result of a combination of different environmental and physical factors as atmospheric conditions, particle properties, characteristics of the canopy. For this latter factor, urban canopy represents unevenly combinations of different types of surface elements that increases the complexity of deposition process phenomena. Therefore, particle dry deposition on urban surfaces is not easy to configure and, although empirical or semi-empirical models in literature have been developed to address this aspect, there is not standardized and commonly accepted criteria, especially for submicron particles. In this paper, comparisons of different dry deposition models and measurement data by experimental campaigns, covering for different surface roughness conditions, i.e. from four Italian cities and urban environments of other countries, are performed. Giardina et al. (2017b) model, by using a Brownian diffusion resistance as proposed in this paper, seems to capture the main dry deposition processes for the examined contexts.

Electrical Properties of Thermal Oxide on 3C-SiC Layers Grown on Silicon

In this paper, the electrical properties of a thermal oxide (SiO2) grown onto 3C-SiC layers on silicon were investigated, by monitoring the behavior of MOS capacitors. In particular, the growth rate of thermal SiO2 was dependent on the different surface roughness condition. However, independent of the roughness a high density of positive charge was detected. The sample having the smooth surface (subjected to CMP) showed a notably improved dielectric breakdown (BD) field. However, the best BD on macroscopic MOS capacitors was still far from the ideal behavior. Additional insights could be gained employing a nanoscale characterization that revealed the detrimental role of persisting extended defects in the semiconductor. In the semiconductor region far from extended defects the nanoscale BD kinetics was nearly ideal.

A numerical study on interface shearing of granular Cosserat materials

This article presents the interface shearing behaviour of a granular soil layer in contact with a bounding structure under motion. For this purpose, an elasto-plastic Cosserat continuum model (EPCCM) and finite element method (FEM) in the updated Lagrange frame are employed. Plane quasi-static shearing of a granular soil layer, bounded by upper and lower rigid boundaries with different surface roughness conditions, is simulated under free dilatancy and constant vertical pressure. Herein, the additional Cosserat kinematical boundary constraints along the bounding surfaces allow a more detailed description of the surface roughness. Specific emphasis is given to the effects of surface roughness as well as the boundary conditions of the entire system on the shear behaviour of layer. According to the obtained results, the shear band location is different in an infinite or finite shear layer depending on the adopted boundary constraints. Further numerical simulations of plane interface shearing are also carried out here using discrete element method (DEM), complementary to Cosserat FE analyses, to better understand the micro-mechanics of granular media near interfaces. FE results are compared with those of experiments as well as DEM simulations and reasonable agreements are seen. The evolution and distribution of state variables and polar quantities in DEM simulations are in proper accordance with the predictions of Cosserat FE model.

Satellite surface soil moisture from SMAP, SMOS, AMSR2 and ESA CCI: A comprehensive assessment using global ground-based observations

Comprehensive assessments on the reliability of remotely sensed soil moisture products are undeniably essential for their advancement and application. With the establishment of extensive dense networks across the globe, mismatches between satellite footprints and ground single-point observations can be feasibly relieved. In this study, five remotely sensed soil moisture products, namely, the Soil Moisture Active Passive (SMAP), two Soil Moisture and Ocean Salinity (SMOS) products, the Land Parameter Retrieval Model (LPRM) Advanced Microwave Scanning Radiometer 2 (AMSR2) and the European Space Agency (ESA) Climate Change Initiative (CCI), were systematically investigated by utilizing in-situ soil moisture observations from global dense and sparse networks. Distinguished from previous studies, several perturbing factors comprising the surface temperature, vegetation optical depth (VOD), surface roughness and spatial heterogeneity were taken into account in this investigation. Furthermore, products' skills under various climate regions were also evaluated.Through the results, the SMAP product captures temporal trends of ground soil moisture, exhibiting an averaged R of 0.729, whereas for overall accuracy, ESA CCI outperformed other products with a slightly smaller ubRMSE of 0.041 m3 m−3 and a bias of −0.005 m3 m−3. This complementarity between SMAP and ESA CCI was further demonstrated under different climate conditions and can afford the reference of their integration for a more reliable global soil moisture product. Though some underestimations still exist, the newly developed SMOS- INRA-CESBIO (SMOS-IC) was illustrated to gain considerable upgrades with regard to R and ubRMSE compared to SMOS-L3 product, especially in dense VOD conditions achieving the highest R compared to other products.Generally, the underestimations of the European Centre for Medium-Range-Weather Forecasts (ECMWF) surface temperature used for SMOS under moderate or high VOD, heterogeneity, and most surface roughness conditions were consistent with the underestimations of the soil moisture product and provide the directions of product promotions. As for LPRM surface temperature, the worse skills can partially explain the unsatisfactory performances for LPRM soil moisture products. In spite of relatively acceptable skills of SMAP and SMOS-IC soil moisture products concerning R under moderate or dense VOD, small surface roughness, low heterogeneity conditions and temperate and cold climate types, advances in soil moisture products under high or even slightly low VOD, high roughness or topography complexity and heterogeneity, as well as in tropical or desert regions, remain challenging. It is expected that these findings can contribute to algorithm refinements, product enhancements (e.g., fusion and disaggregation) and hydrometeorological usages.

Dendritic Morphologies of Hot-Dip Galvanized Zn-0.2 Wt Pct Al Coatings on Steel Sheets

The dendritic morphologies of hot-dip galvanized Zn-0.2 wt pct Al coatings on steel sheets with two different surface roughness conditions were systematically examined as functions of the inclination angle and axis of the Zn basal plane with respect to the sheet surface by using electron backscattered diffraction. When the inclination axis of the basal plane was $$ \langle 1\bar{2}10 \rangle $$ , the dendrite changed its morphology by following the sequence of six-fold → eight-fold → elongated X → elongated X + C patterns with increasing inclination angle. When the inclination axis was $$ \langle 10\bar{1}0 \rangle $$ , the sequence of morphological patterns on the mirror-polished steel substrate was six-fold → eight-fold → two-fold → four-fold, whereas, for the steel substrate with a rough surface, the eight-fold pattern was missing in the sequence. These sequences of morphological changes indicated the presence of a third family of preferred dendritic growth directions, in addition to the two previously known families of $$ \langle 10\bar{1}0 \rangle $$ and $$ \langle 0001 \rangle $$ . The third growth direction family is proposed to be those normal to the $$ \left\{ {1\bar{2}11} \right\} $$ planes. The absence of the eight-fold pattern on the rough steel surface was attributed to the surface undulation that perturbed the growth in the six weakly preferred directions toward the two strongly preferred $$ \langle 10\bar{1}0 \rangle $$ directions.

Effect of the specific surface topography on surface wettability of chromium-based coatings

ABSTRACTSurfaces featuring hydrophobic behaviour are generally prepared by a wide spectrum of technologies featuring different process complexity (anodic oxidation, lithography, electrodepositing, etc.). The aim of the work was to use a relatively simple method of magnetron sputtering to prepare metallic hydrophobic surface. Chromium coatings were selected due to their high adhesion to steel and corrosion resistance while conserving certain level of hardness and ductility. The tested coatings included pure Cr and pure Cr with CrN interlayer. The resulting contact angle value of up to 111° has confirmed hydrophobic behaviour. The resulting surface morphology is formed by almost perfectly developed crystals in the shape of hexagonal pyramids providing a suitable surface roughness conditions for hydrophobicity.

The prediction of load distribution in four-row cylindrical roller bearings under the elastohydrodynamic lubrication based on boundary element method

In order to get the prediction of load distribution in four-row cylindrical roller bearing under the elastohydrodynamic lubrication (EHL), a new bearing Boundary Element Method (BEM) is proposed, which is based on the elastic contact BEM and EHL theory. Firstly, the basic theories of the bearing BEM are introduced. Secondly, the basic equations of the EHL theory of finite length line contact are described, and the calculation program is compiled by the Finite Difference Method (FDM), by which the EHL characteristics of four-row cylindrical roller bearing under smooth condition are analyzed. Thirdly, the thickness of lubricant oil film and the surface roughness are coupled with the boundary integral equation in the form of contact clearance, and also the friction coefficient equation derived by EHL theory. The boundary integral equation of bearing BEM under the EHL condition is established, and the calculation program is compiled. Then, load and pressure distributions of a four-row cylindrical roller bearing are simulated numerically under different surface roughness conditions. Finally, the load distribution of the four-row cylindrical roller bearing is tested, and the experimental data and the simulation results are compared, which proves the validity and effectiveness of the new bearing BEM.

Influence of Water Absorption on Static Friction of Pure and Friction-Modified PA6 Polymers

In the present study, static coefficients of friction of pure and friction modified (FM) polyamide 6 (PA6) polymers against primer-coated steel surfaces were investigated under a series of nominal contact pressures and by considering the influences of water absorption by the polymer, temperature, counter-body surface roughness and lubrication conditions. Under the majority of the test conditions investigated, FM PA6 exhibited lower static friction than pure PA6. Under unlubricated conditions, this was due to the low adhesion of the FM PA6 provided by its friction modifying inclusions; while under lubricated conditions, a combination of softening due to water absorption and decreased adhesion provided by its friction modifiers enabled lower static friction, especially at medium and high contact pressures.

Comparison of high-resolution airborne soil moisture retrievals to SMAP soil moisture during the SMAP validation experiment 2016 (SMAPVEX16)

The NASA's Soil Moisture Active Passive (SMAP) mission conducted a field experiment with its partners over two 40-km agricultural domains in Iowa and Manitoba in the summer of 2016 to address concerns observed in SMAP soil moisture (SM) retrievals over agricultural areas. The experiment featured airborne Passive Active L-band System (PALS) flights over each domain with intensive ground measurements and dense networks of SM monitoring stations. With two intensive observation periods separated in time (May 28–June 20 and July 14–August 16), the flights captured both early-season/low vegetation and later-season/high-vegetation conditions. The comparison of the PALS brightness temperature (TB) measurements to the SMAP TB observed over the sites resulted in root mean square difference (RMSD) of 2.8 K and 4.0 K for vertical and horizontal polarizations, respectively. The subsequent SM analysis rescaled the PALS TB with the SMAP TB to allow equitable comparisons between the SM retrievals from the two instruments. The PALS SM retrieval algorithm used the SM sampled by the ground teams during the overpass days for tuning, and was parameterized by a high-resolution vegetation water content product calibrated using vegetation samples collected during the experiment. The tuning process was not able to find a satisfactory result with a temporally constant set of parameters in the single channel algorithm for the two intensive observation periods of the experiment. This result indicated that the rapid change in the vegetation structure during the growth stages and likely variation in the surface roughness conditions were not compatible with rigid parameterization over the entire period. However, using seasonally variable parameters we found that it was possible to retrieve soil moisture with satisfactory accuracy. Comparative analysis with the SMAP SM product included aggregation of the PALS SM to the SMAP pixel-scale. The RMSD between the PALS SM and the aggregated manual field samples was <0.04 m3/m3 with Pearson correlation >0.85 for both sites. The comparison between different in situ sources indicated that the soil moisture network measurements were not the source of the large biases observed for SMAP over the sites reported in earlier studies. Therefore, the results suggested the rapidly growing vegetation and the early-season surface condition changes not captured by the SMAP algorithm caused the SMAP retrieval errors. In addition, the significant deviations of the vegetation water content used by the SMAP product from the calibrated vegetation water content obtained during the experiment compounds the problem.

Hydraulic Performance of Concrete Block Pavement under High Rainfall Intensities

High rainfall intensity will generate different response on the concrete block pavement (CBP) performance. A study found that larger openings of CBP did not lead more water penetrated. In other study, larger openings can lead greater decrease in runoff velocity. The correlation between the openings, water penetration and runoff velocity has remained unclear. In this study, we investigated hydraulic performance of CBP as an impact of surface roughness condition, under high rainfall intensities, saturated sub-base layer, and various slope surfaces. We conducted experiment using a 2 m by 6 m of rectangular CBP layer with herringbone 90 and basket-weave pattern. We used a modified dye tracing method in view to monitor the surface flow velocity under various high rainfall intensities. The results showed that hydraulic performance of surface runoff in the CBP layer was more influenced by the surface roughness condition. The roughness condition was very sensitive to the change in surface configuration of the CBP. The relationship between rainfall intensity, surface slope and roughness number followed polynomial functions. A further study is required to investigate the appropriate quality of CBPs, which have high durability applied over a steep slope surface and under high rainfall intensities.

On the flash temperature under the starved lubrication condition of a line contact

Abstract To investigate the effect of the inlet starvation severity on the flash temperature, which dictates the scuffing failure, a thermal mixed elastohydrodynamic lubrication model is developed for line contacts operating under the starved lubrication condition. Utilizing a generalized Newtonian Reynolds equation, the lubricant viscosity dependence on the shear rate, as well as on the pressure and temperature, is incorporated for the proper and accurate modeling of the tribological behavior under the high sliding condition. A film fraction parameter is employed in the Reynolds equation to include the starvation and cavitation description. Considering different operating and surface roughness conditions, a parametric study is performed to show an asymptotic relationship between the flash temperature and the inlet starvation severity.

Effect of bond-coat surface roughness on failure mechanism and lifetime of air plasma spraying thermal barrier coatings

This work investigates the failure mechanism of an air plasma spraying (APS) thermal barrier coatings (TBCs) with various bond coat (BC) surface toughness under constant temperature loading condition. Results show that the increased BC surface roughness decreased the lifetime. Moreover, the relationship between the TGO depth and the lifetime can be well described by linear law. The failure mechanism of the TBCs samples was studied by cross-sectional morphologies observation and using the finite element method (FEM). Cracks in the TBCs samples with higher BC surface roughness are initiated from the defects on the BC caused by Al depletion in the BC layer. However, cracks in the samples of TBCs with lower BC surface roughness condition preferentially occur at the TC-TGO interface. This finding could be attributed to the high mismatch stresses in the TC-TGO interface.

Effect of surface roughness on film formation properties of screw tightening lubricant PIB

Abstract This paper describes the film formation properties of polyisobutylene (PIB) lubricant under various surface roughness conditions. PIB lubricant has been proposed as a new type of screw tightening lubricant, however the lubrication mechanism in the screw tightening process is yet to be understood. In this study, the in-situ observation tests were conducted under the starved lubrication condition, in which a thin film lubrication regime was simulated. The results showed that film thickness was greater than the surface roughness. Under the high roughness conditions, the time at which direct contact was prevented was shorter. In addition, the occurrence of wear was related to the lambda ratio Λ, and under the high roughness conditions, the friction coefficient increased with time owing to expansion of the wear area. It was also shown that under the fully starved condition, the shear stress did not depend on the shear rate, moreover, its value was constant under all roughness conditions. These results suggest that (i) solid-like PIB film was formed on the contact area under the starved condition and (ii) the formation of a film with a high limiting shear stress potentially inhibits wear. These results were consistent with the results of a tightening test.

Ratchetting–multiaxial fatigue damage analysis in gear rolling contact considering tooth surface roughness

Under the combined effect of the tooth surface roughness and heavy load condition, gear materials might experience both the fatigue damage and the ratchetting damage. An elastic-plastic finite element contact fatigue model is proposed considering the optically measured tooth surface roughness and the gear contact geometry. The kinematic hardening constitutive equation and the Jiang and Sehitoglu ratchetting-multiaxial fatigue model are applied, and the contribution of the ratchetting-fatigue damage in the mechanism of gear contact fatigue problems is discussed. Results reveal that the surface roughness can promote the emergence of ratchetting behavior within a very shallow area near surface. Furthermore, the effect of the normal load condition on the ratchetting-fatigue damage is also discussed.

Mirror-Surface Finishing by Integrating Magnetic-Polishing Technology with a Compact Machine Tool

In recent years, owing to the advent of mobile phones, product miniaturization and multifunctionalization have rapidly progressed. However, the large-sized machine tools for the manufacture of small products waste a considerable amount of space and power. The present study aimed at applying a magnetic-polishing method using a ball-end mill-type tool to examine the optimum processing conditions. This was done to apply a mirror finish for the integration of the cutting and polishing processes by using the small machine tool. The magnetic-polishing effect was evaluated from the point of view of the polishing amount, surface roughness, specimen shape, and mirror-surface condition. In addition, the movement of the paste during polishing was observed through images obtained through a high-speed camera. The movement of the paste is considered for effective polishing and other cases. Accordingly, various magnetic-polishing techniques were used for irregularities and step shapes. Various conditions were also examined, and a stable condition was determined. The results reveal that the amount of polishing paste significantly influences the polishing movement. In addition, a sufficient polishing effect could be obtained by duplicating the polishing course by using a sine wave course.

Statistics and spectra of turbulence under different roughness in the near‐neutral atmospheric surface layer

AbstractAccurate knowledge of the contacts between surface roughness and the resultant wind speed are important for climatic models, wind power meteorology, agriculture and erosion hazards especially on sand saltation in arid and semi‐arid environments, where vegetation cover is scarce. In this study, synchronous measurements of three‐dimensional wind speed below 5 m are carried out in three different surface roughness conditions in Minqin, China, and the difference in the turbulence statistics and the structure of the very large‐scale motions (VLSMs) were revealed. The results show that the slope of the mean wind profile (MVP), the turbulent kinetic energy (TKE) and Reynolds stress increase with the surface roughness. The roughness seems to suppress the ejection events and the surface roughness will not only weaken the energy of the VLSMs, but also reduce the scale values of VLSMs near the wall. These influences may cause some changes regarding the dust transportation in streamwise and vertical directions during the sand and dust storm (SDS). That is, the decrease of the mean velocity near the ground will reduce the dust transportation in the streamwise direction and influence of the roughness on the ejection and sweep events will change the dust transportation in the vertical direction. Furthermore, the increase of roughness will weaken the scale and energy of VLSMs, which will lead to the decrease of the capacity of dust transportation. © 2019 John Wiley &amp; Sons, Ltd.