3D Roughness Research Articles

Selected Properties of the Surface Layer of C45 Steel Samples after Slide Burnishing.

This paper presents the experimental results of a study investigating the impact of the machining fluid type, the variable factor, used in slide burnishing on 2D and 3D surface roughness; surface topography; Abbott-Firestone curve shape; microhardness; and SFE (surface free energy). In the experiment, pre-ground, ringed samples of C45 steel were used. The results showed an over eight-fold decrease in the value of the Ra (arithmetical mean deviation) parameter and over a five-fold decrease in the Rt (total height of profile) parameter in relation to their values after grinding. The parameters Rpk (reduced peak height), Rk (core roughness depth), and Rvk (reduced valley depth) were also reduced. The Abbott-Firestone curve after slide burnishing changed its angle of inclination (it was more flattened), and the material ratio Smr increased. The reduction in the Rpk and Rk parameters and increased material ratio will most likely contribute to restoring the functionality of these surfaces (increased resistance to abrasive wear). After slide burnishing, the maximum 25% increase in microhardness was obtained compared to the value after grinding, while the layer thickness was 20 μm. The surface energy of elements subjected to slide burnishing using various machining fluids slightly increased, or its value was close to that of the ground surface. The most favourable properties of the surface layer in terms of mating between two elements were obtained for a part that was slide-burnished with a mixture of oil + polymethyl methacrylate (PMM) + molybdenum disulphide (MoS2).

A New 3D Statistical Parameter for Determining Roughness of Joint Surfaces Considering Shear Direction and Asperity Features

The engineering rock mass is a multi-fracture body crisscrossed by geologic structure planes, and its safety is affected by the rock joints' mechanical properties and morphological features. The joint roughness coefficient (JRC) is a vital characterization method to describe joint surface roughness. Its precise quantization is a crucial factor in predicting shear strength. However, JRC in recent research did not reflect the directional effect of the joint morphology. A new 3D roughness parameter WAD (weighted apparent dip) was proposed to estimate JRC based on the apparent dip angle of the contact unit. The proposed parameter comprehensively reflects the contribution of shear direction and asperity features to the roughness. Based on the ten standard roughness profiles, we investigated the directionality of the WAD and studied the influence of the sampling interval (Sai) on WAD and their correlation with JRC. And the practicability of WAD in evaluating JRC was well verified by the comparison between the indoor test and calculated results with different roughness and shear directions, and the results showed that WAD could accurately estimate the shear strength of the joint rock.

3D bevel surface topography analysis and roughness prediction by considering the cutter-workpiece dynamic interaction

3D bevel surface topography analysis and roughness prediction by considering the cutter-workpiece dynamic interaction

In-depth analysis of the effect of physicochemical properties of ionic liquids on anti-icing behavior of silicon based-coatings

This study dissects the use of room temperature ionic liquids (RT-ILs) in a dynamic surface for anti-icing applications. Anti-icing properties of ILs-containing PDMS-based coatings fabricated by two different types of ILs, are evaluated to establish a relationship between the anti-icing behavior and physicochemical properties of the ILs. The surface chemistry of coatings and the existence of distinctive groups of the ILs anions on the surface of coatings characterized by Attenuated Total Reflectance-Fourier transform infrared (FTIR) spectroscopy (ATR-FTIR) and confirmed by using X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy-energy dispersive X-ray analysis (SEM/EDX). The 3D profiles and roughness parameter of the surfaces were investigated by a confocal laser microscopy profiler. Regarding the importance of correlation between wettability and ice adhesion, the wettability of coatings was studied. The results show a significant reduction 30–40% in sliding angle (SA) and contact angle hysteresis (CAH) in ILs-containing coatings. Differential scanning calorimetry (DSC), freezing delay time, push-off and centrifugal adhesion tests (CAT) served to distinguish the performance of the two ILs in regard to ice nucleation temperature and formation time, and ice adhesion strength, respectively. The 60–70% reduction in ice adhesion strength for the IL-containing coatings, obtained by push-off test, is due to the presence of strong ionic hydrogen bounded water and the formation of self-lubricating quasi liquid layer that can function at much lower temperature. Solid-state nuclear magnetic resonance (NMR) spectroscopy has confirmed the presence of nonfrozen water molecules at the interface. Consequently, incorporating ILs into coatings provides an effective approach to delay ice nucleation, restrict ice growth recrystallization and reduce ice adhesion strength. A comparison of enhanced anti-icing performance of ILs-containing coatings highlights the significant influence of minor changes in the chemical structure of ILs on their potential for anti-icing applications.

Probabilistic prediction on three-dimensional roughness of discontinuity based on two-dimensional traces under rock tunnel excavation based on Bayesian theory

Three-dimensional (3D) roughness of discontinuity affects the quality of the rock mass, but 3D roughness is hard to be measured due to that the discontinuity is invisible in the engineering. Two-dimensional (2D) roughness can be calculated from the visible traces, but it is difficult to obtain enough quantity of the traces to directly derive 3D roughness during the tunnel excavation. In this study, a new method using Bayesian theory is proposed to derive 3D roughness from the low quantity of 2D roughness samples. For more accurately calculating 3D roughness, a new regression formula of 2D roughness is established firstly based on wavelet analysis. The new JRC3D prediction model based on Bayesian theory is then developed, and Markov chain Monte Carlo (MCMC) sampling is adopted to process JRC3D prediction model. The discontinuity sample collected from the literature is used to verify the proposed method. Twenty groups with the sampling size of 2, 3, 4, and 5 of each group are randomly sampled from JRC2D values of 170 profiles of the discontinuity, respectively. The research results indicate that 100%, 90%, 85%, and 60% predicting JRC3D of the sample groups corresponding to the sampling size of 5, 4, 3, and 2 fall into the tolerance interval [JRCtrue–1, JRCtrue + 1]. It is validated that the sampling size of 5 is enough for predicting JRC3D. The sensitivities of sampling results are then analyzed on the influencing factors, which are the correlation function, the prior distribution, and the prior information. The discontinuity across the excavation face at ZK78 + 67.5 of Daxiagu tunnel is taken as the tunnel engineering application, and the results further verify that the predicting JRC3D with the sampling size of 5 is generally in good agreement with JRC3D true values.

Quantitative characterization method of 3D roughness of rock mass structural surface considering size effect

The surface morphology of the structural surface of the rock mass plays a crucial role in determining its macroscopic physical and mechanical properties, including shear strength and seepage characteristics. The morphological characteristics of the rock mass structure exhibit significant anisotropy and size effects. The distribution characteristics of the two key indicators that affect the morphological characteristics of the structure were analyzed, revealing that the undulation degree and undulation angle conform to the normal distribution and Weibull distribution, respectively. The present study defines a method for quantifying the 3D roughness of structural surface based on the features of undulation degree and undulation angle. Through quantitative analysis, it was observed that the roughness parameters exhibit anisotropic characteristics at different sampling intervals and shear directions.

3Y-TZP electrostatic painting to increase bond strength to dentin and dental prostheses

Although the clinical method used to improve the adhesion of zirconia prostheses to other materials is sandblasting or acid etching surface, the failure rate of the bond is high. The present work aims to propose an innovative method of zirconia surface painting with an electrostatic technique using epoxy powder paint with antibacterial and antifungal properties to improve the adhesion to dentin. The zirconia samples were divided into 4 groups: without surface painting (GC), painted without surface treatment (G1), hydrofluoric acid etching before painting (G2), and blasted with alumina before painting (G3). The samples were characterized by X-ray diffraction, scanning electron microscopy, Vickers hardness, 3D roughness, and cytotoxicity. Shear bond strength (SBS) tests were used to measure the zirconia bonding to synthetic dentin (NG-10 polymer). The opacity of painted zirconia was evaluated using a spectrophotometer with contrast ratio as a translucency parameter. The results showed the sintered zirconia had high densification, and submicrometric tetragonal (t-ZrO2) and cubic (c-ZrO2) grains. The bonding shear strength of zirconia without surface painting and surface treatment (3.51 MPa) was the lowest. The highest bonding strength was painted zirconia without surface treatment (15.51 MPa). The zirconia etched with HF had a lower shear strength (5.75 MPa) than the zirconia blasted with alumina (7.76 MPa). As the painting coating thickness increased, the opacity increased. The cytotoxicity tests showed that the coated zirconia is biocompatible. The zirconia painting with epoxy powder paint methodology facilitates the manufacture of dental prostheses and increases the shear bonding strength to dentin.

Analysis of scratch visibility on polymeric surfaces using 3D roughness measurement and the bidirectional reflectance distribution function (BRDF)

The evolution of visual aspect of polymers with wear is a fundamental problem in numerous industries. In this article, we study the visibility of scratches. Fifty parallel micro-scratches are performed on three samples differing only by their values of gloss. Scratches are much more visible on glossy samples than on mat ones, in agreement with previous works. To interpret these results, a bidirectional reflectance distribution function (BRDF) model is developed to compute the way a surface scatters light based on a roughness measurement described by a distribution of microfacet orientations. In this paper, this BRDF model is applied to investigate the influence of the scratches on the light scattering properties of a surface. Roughness measurements are performed on the surfaces before and after scratching. Then, the BRDFs are computed and compared to each other. The visibility of scratches strongly depends on how much they modify the roughness slope distribution function of the surface. Depending on the initial gloss of the surface, this leads to more or less contrast. Finally, a visibility criterion is proposed based on this contrast effect.

Three-Dimensional Pore Structure Characterization of Bituminous Coal and Its Relationship with Adsorption Capacity.

Bituminous coal reservoirs exhibit pronounced heterogeneity, which significantly impedes the production capacity of coalbed methane. Therefore, obtaining a thorough comprehension of the pore characteristics of bituminous coal reservoirs is essential for understanding the dynamic interaction between gas and coal, as well as ensuring the safety and efficiency of coal mine production. In this study, we conducted a comprehensive analysis of the pore structure and surface roughness of six bituminous coal samples (1.19% < Ro,max < 2.55%) using various atomic force microscopy (AFM) techniques. Firstly, we compared the microscopic morphology obtained through low-pressure nitrogen gas adsorption (LP-N2-GA) and AFM. It was observed that LP-N2-GA provides a comprehensive depiction of various pore structures, whereas AFM only allows the observation of V-shaped and wedge-shaped pores. Subsequently, the pore structure analysis of the coal samples was performed using Threshold and Chen's algorithms at ×200 and ×4000 magnifications. Our findings indicate that Chen's algorithm enables the observation of a greater number of pores compared to the Threshold algorithm. Moreover, the porosity obtained through the 3D algorithm is more accurate and closely aligns with the results from LP-N2-GA analysis. Regarding the effect of magnification, it was found that ×4000 magnification yielded a higher number of pores compared to ×200 magnification. The roughness values (Rq and Ra) obtained at ×200 magnification were 5-14 times greater than those at ×4000 magnification. Interestingly, despite the differences in magnification, the difference in porosity between ×200 and ×4000 was not significant. Furthermore, when comparing the results with the HP-CH4-GA experiment, it was observed that an increase in Ra and Rq values positively influenced gas adsorption, while an increase in Rsk and Rku values had an unfavorable effect on gas adsorption. This suggests that surface roughness plays a crucial role in gas adsorption behavior. Overall, the findings highlight the significant influence of different methods on the evaluation of pore structure. The 3D algorithm and ×4000 magnification provide a more accurate description of the pore structure. Additionally, the variation in 3D surface roughness was found to be related to coal rank and had a notable effect on gas adsorption.

Can the splitting joint reproduce the characteristics of the natural joint in the lab? —A comparison study based on the roughness analysis and shear test

Splitting joints have been widely used to study the morphology characteristic and shear behavior of rock joints in the laboratory. There are some differences between the splitting joint and natural joint both in morphology characteristic and shear behavior. To quantitatively compare the differences, the present study used several splitting joints and natural joints to carry out the roughness analysis and direct shear test. Six profiles were extracted from each joint surface with a 30° interval to calculate the 2D roughness parameters (i.e., amplitude roughness parameter, average asperity inclination, root-mean-square of profile slope, and joint roughness coefficient). These parameters of the natural joints have a wide range and have obvious fluctuation. On the contrary, these parameters of the splitting red sandstone joints converge on a small range with tiny fluctuation, even calculated from different joint surfaces. The directional parameter (θ⁎max(C + 1)) was adopted to calculate the 3D roughness with a 5° interval. The directional parameter of the natural joints in range of 0° ∼ 360° forms a peanut, a prolate ellipse, or a gourd shape, presenting significant anisotropy. For the splitting joints, it forms a circle or a roughly circular shape, presenting insignificant anisotropy. The asperity heights of natural joints mainly present an irregular distribution, and they present an approximately normal distribution in few joints. For the splitting joints, the asperity heights generally obey a normal distribution. It indicates that there are huge differences between natural joint and splitting joint in morphology characteristic. To study the shear behavior, two types of joint were reconstructed for repeated test. The mechanical performance and failure characteristic of the splitting joint under different shear directions are similar. On the contrary, those of the natural joints under different shear directions are different, presenting obvious anisotropy. Based on the comparative analysis of the natural joints and the sandstone splitting joints in the present study, there is substantial difference between two types of joints both in morphology characteristic and shear behavior. The splitting joints cannot reproduce the characteristics of the natural joints well.

Predictions of friction and temperature at marine cam-tappet interface based on mixed lubrication analysis with real surface roughness

The working conditions of cam-tappet pairs in marine diesel engines are directly influenced by the engine output power, the operational speed, the temperature, as well as the components surface micro-morphology, etc., which cause the cam-tappet pairs work in the mixed lubrication state, thus the interfacial friction, pressure and temperature rise are vital to engine performance, efficiency, and durability. An interfacial friction–temperature prediction model for the cam-tappet pairs, considering the effects of transient working conditions and the real surface roughness, is developed in the present study, based on the theories of the transient mixed EHL and the heat transfer under the condition of a fast moving heat source. The numerical results of surface temperature rise are compared with those from the Blok formula, and a good agreement is found. The obtained results show that the presence of 3D roughness may lead to a decrease in the lubricant film thickness, and the surface temperature rise of tappet may exceed 700 K, which is close to the material scuffing temperature, causing the surface failure due to scuffing and wear. If increasing the cam speed and base circle radius within certain range, it may lead to the increment of film thickness and reduction of surface temperature rise, thus the lubrication effectiveness is increased. In addition, using cast aluminum bronze may significantly reduce the surface temperature rise and improve the interfacial characteristics.

Exploring the capabilities of portable device photogrammetry for 3D surface roughness evaluation

ABSTRACT The feasibility of using a portable photogrammetric device to digitalise rock surface roughness is investigated. Structured light 3D scanner, terrestrial LiDAR scanner, and portable photogrammetry device are used to scan precast different roughness lab-scale specimens. The reconstructed 3D surface is evaluated for accuracy using point cloud distance, joint roughness coefficient, and 3D roughness parameters. Results show that the portable device can reconstruct a 3D model comparable in accuracy to a structured light 3D scanner in 15 minutes. The proposed method is applied to laboratory-scale model reconstruction, with the potential to scan rock surfaces efficiently and economically in a mine.

A 2D roughness method for irregular interface of rock-backfill

A simple and reasonable roughness method for irregular interface of rock-backfill is significant for estimating the long-term stability of mine stopes in underground engineering. In this paper, two new concepts, contribution height difference (CHD) and average contribution height difference (ACHD), were presented through analyzing the influences of whole movement process of asperity and properties of contact material on the shear strength properties of interface. Occupying the presented concepts and combining with the fractal theory, a 2D roughness method for irregular interface of rock-backfill was created, which depends on fractal dimension Dp and direction-correlated parameter ACHD0. The roughness index Iif was introduced to quantitatively characterize the roughness of irregular interface. The results of scanning experiment and shear strength experiment about granite and cement backfill were used to verify the proposed 2D roughness method. The application analysis shows that the proposed roughness method has very outstanding advantage for irregular interface of rock-backfill, which provides the evolution of roughness method by involving the directionality of roughness and resolving the effect of sampling interval. The roughness index Iif can predict the shear strength of interface between rock and backfill. The parameters described in this work are easy to measure in field and also they are very convenient in usage.

Metrological relations between the spray atomization parameters of a cutting fluid and formation of a surface topography and cutting force

Aerosol formation parameters are very important, as they are responsible for the ability of spray-forming droplets to penetrate the area to which they are applied. Research into modifying these parameters can therefore provide a solution for increasing the effectiveness of cooling and lubrication of the cutting zone during machining. This is particularly important for hard-to-cut materials such as titanium alloys, the machining of which requires the selection of effective cooling/lubricating methods to reduce tool wear or improve the machined surface quality. Previous research indicates that any modification in the air or oil flow rates – which form aerosols during cutting in minimized quantity lubrication (MQL) technique – contribute to an increase or decrease in the penetration of droplets into the cutting zone. It can consequently has a significant impact on machining results. This paper presents results on the effect of volumetric air flow rate P and cutting fluid mass flow rate E during the MQL cutting method on the machined surface topography after turning of Ti6Al4V alloy and the values of the cutting force. On the basis of conducted computational fluid dynamics (CFD) simulation studies, it was shown that the droplet size is more influenced by the change in volumetric air flow rate than cutting fluid mass flow rate and also that as the value of P increases, the droplet diameters decrease and the spray angle increases, which promotes the penetration of the cutting zone. As a result of the analysis of selected 3D surface roughness parameters, as well as contour maps, isometric views and material ratio curves, it was shown that the most favorable machined surface topography is being formed during MQL turning method with a volumetric air flow rate above 20 l/min. Whereby, with conditions of P = 30 l/min and E = 1.182 g/min, the machined surface topography is characterized by a uniform distribution of irregularity peaks and valleys, compared to the MQL turning with other tested values of aerosol formation parameters.

Study on the characterization of differential weathering feature based on surface roughness theory and 3D laser scanning: A case study of the Suoyang Ancient City

Earthen heritage sites have been undergoing lengthy surface weathering since they were built, which can pose a severe threat to the protection and utilization of these cultural treasures. Especially for differential weathering, one of the most common surface weathering patterns of earthen heritage sites in northwestern China, has not been well studied yet. Hence, in this paper, Suoyang Ancient City was selected as the study area, and six analysis domains (S1 to S6) exhibiting various differential weathering degrees were determined on wall faces and their morphological data were collected by a 3D laser scanner. Based on the point cloud data, the morphology of each domain was digitalized and reconstructed, and ten typical profiles were selected for roughness analysis. Concretely, for these profiles, six roughness parameters, including average asperity inclination (Ai), mean curvature (R′da), textural slope parameter (Z2), roughness coefficient (Rp), self-affine fractal dimensions (A and D) and directional roughness metric (G(i)) were calculated to characterize their differential weathering features. The results show that the wall with a higher differential weathering degree has greater values of Rp, G(i), A and D. It can also be found that different roughness indicators can reflect different wall surface morphological characteristics. In addition, the main driver of differential weathering developing is the prevailing sediment-laden wind, and the degree of differential weathering is also affected by the building techniques, wall endowment environment, wall orientation and morphology. Finally, according to the roughness values and wall surface morphology, the differential weathering degrees were classified into five grades (from level I to level V). In this case, the differential weathering degrees of S2 (level IV) and S5 (level IV) are the highest, followed by S3 (level III), S6 (level III), S1 (level II) and S4 (level II) respectively. Overall, the proposed approach based on 3D scanning and surface roughness is feasible to characterize the differential weathering degree, contributing to better prevention and mitigation of damage on earthen heritage sites.

Surface roughness effect on dynamic wettability in imbibition process

Dynamic wetting on rough surface is important in imbibition processes in micro- and nano- channels. Due to high computational costs, the previous studies by direct numerical simulations mostly adopted two-dimensional (2D) simplifications of surface with roughness. The cutting-edge advances in high performance computing make it possible to conduct three-dimensional (3D) direct simulations. This work presents 3D simulations on channel flows with roughness on walls via the GPU-based multiphase lattice Boltzmann method (LBM). The effects from 3D roughness morphology are investigated. In contrast to the wettability alternation in 2D rough ones, the 3D rough hydrophilic surfaces remain hydrophilic and Wenzel state at even low capillary numbers (Ca). The apparent contact angle follows the hydrodynamic model on rough surfaces except for a more sensitivity to Ca. The results also indicate that the 2D simplifications overestimate the pressure drop for rough channels, while underestimate over 20% for smooth channels. Therefore, it is crucial to consider 3D structures of surface roughness for dynamic wetting in real channels.

ANALYSIS OF SELECTED FUNCTION-DEFINING 2D SURFACE ROUGHNESS PARAMETERS IN TANGENTIAL TURNING

Among other, more frequently analysed surface topography parameters, the function-defining parameters must be analysed in different machining procedures to outline their application possibilities. These values are the core roughness, the reduced peak height, the reduced valley depth, the skewness, and the kurtosis of the roughness profiles. Tangential turning is a promising machining procedure, which can produce ground-like surfaces with twist-free properties by defined cutting edged tools. The achievable productivity is also very high. Therefore, in this paper, these roughness parameters were analysed from 2D roughness profiles measured on surfaces machined by tangential turning.

Applications of Chromatic Confocal Technology in Precision Geometric Measurement of Workpieces

Chromatic confocal technology is increasingly applied in industries that require high-precision geometric measurements such as aerospace, naval ordnance, and medical electronics owing to its advantages in testing accuracy, real-time performance, anti-interference, and no damage to tested workpieces. This paper introduces the measurement principle of chromatic confocal technology and the structure of chromatic confocal sensors, and enumerates several typical application scenarios of the technology from the aspects of thickness measurement, profile, 3D topography scanning, roughness measurement, and wafer comprehensive parameter measurement. It also looks into potential development directions of chromatic confocal technology.

Mechanical properties of CAD/CAM polylactic acid as a material for interim restoration

Statement of problemBiomaterials, including polymethyl methacrylate (PMMA) and bisacrylate, have been widely used as conventional interim materials and may exhibit cytotoxicity or systemic toxicity. PurposeThis study was designed to compare the mechanical properties of polylactic acid (PLA) as an alternative to conventional dental polymers for computer-aided design and manufacturing (CAD/CAM). Material and methodsFour groups (n = 20 per group) of CAD/CAM polymers were assessed. Specimens of PLA (PLA Mill) and PMMA (PMMA Mill) for subtractive manufacturing, PLA for fused deposition modeling (PLA FDM), and bisphenol for additive manufacturing by stereolithography (Bisphenol SLA) were fabricated into 2-mm-wide, 2-mm-thick and 25-mm-long specimens using a milling machine, an FDM printer, and an SLA printer, respectively.The flexural strength (FS) and elastic modulus (EM) were calculated. The surface roughness and Shore D hardness were analyzed with a 3D optical surface roughness analyzer and a Shore durometer, respectively. ResultsPLA Mill showed the lowest FS (64.9 ± 8.28), followed by PLA FDM (104.27 ± 4.42 MPa), PMMA Mill (139.2 ± 20.95 MPa), and Bisphenol SLA (171.56 ± 15.38 MPa), with statistically significant differences. PLA FDM showed the highest EM, followed by PLA Mill, Bisphenol SLA, and PMMA Mill. Significant differences were observed not only between PMMA Mill and Bisphenol SLA but also between PLA FDM and PLA Mill. The lowest Shore D hardness was observed for PLA FDM, followed by PLA Mill, PMMA Mill, and Bisphenol SLA, which showed the highest value among the 4 groups, with significance. The highest values for the surface roughness parameters were observed for PLA Mill, and the lowest were observed for Bisphenol SLA. ConclusionsAmong the tested CAD/CAM polymers, Bisphenol SLA was the most durable material, and the mechanical properties of PLA FDM were within the clinically acceptable range.

A consecutive joint shear strength model considering the 3D roughness of real contact joint surface

A consecutive joint shear strength model for soft rock joints is proposed in this paper, which takes into account the degradation law of the actual contact three-dimensional (3D) roughness. The essence of the degradation of the maximum possible dilation angle is the degradation of the 3D average equivalent dip angle of the actual contact joint asperities. Firstly, models for calculating the maximum possible dilation angle at the initial and residual shear stress stages are proposed by analyzing the 3D joint morphology characteristics of the corresponding shear stages. Secondly, the variation law of the maximum possible dilation angle is quantified by studying the degradation law of the joint micro convex body. Based on the variation law of the maximum possible dilation angle, the maximum possible shear strength model is proposed. Furthermore, a method to calculate the shear stiffness degradation in the plastic stage is proposed. According to the maximum possible shear strength of rock joints, the shear stress-shear displacement prediction model of rock joints is obtained. The new model reveals that there is a close relationship between joint shear strength and actual contact joint roughness, and the degradation of shear strength after the peak is due to the degradation of actual contact joint roughness.