Three-dimensional Roughness Parameters Research Articles

The influence of fracture surface morphology on propped fracture conductivity in tight sandstone reservoir

The investigation on the influence of fracture morphology on conductivity mainly focuses on the research of non-propped fracture conductivity. Few studies, however, have addressed the relationship between fracture surface characteristics and propped fracture conductivity. In this paper, by defining the maximum volume capacity of the fracture surface (VMF), according to the size relationship between the filling volume of proppants and VMF, the distribution state of proppants in propped fractures are divided into four modes, which can reflect the distribution state of proppant particle at different positions of the same fracture or different proppant concentrations in the rough surface fractures. Taking rough-surface rock samples and smooth-surface rock samples from tight sandstone reservoirs as experimental materials, a series of propped fracture conductivity tests in four modes are designed, supplemented by a various of methods such as refined characterization of three-dimensional roughness parameters of fracture surface and evaluation of proppant breakage rate. The influence of fracture morphology on the conductivity of propped fractures is systematically studied. The results show that the influence of fracture morphology on the conductivity of propped fractures varies with the distribution modes, which is closely correlated with the filling state and volume proppant filled in fractures. The influence of fracture morphology on the fracture conductivity in different distribution modes is revealed. Especially under the condition of multi-layer proppants, a new damage mechanism of fracture conductivity caused by fracture surface morphology is proposed, which is defined the “Retention Effect” of proppant particles caused by fracture surface morphology. The damage degree of this effect is characterized by defining “Damage Index of Fracture Conductivity on Rough Surface” (RFCI), which can quantitatively and accurately describe the damage degree of propped fracture conductivity caused by fracture surface morphology. The research results of this paper are helpful to understand the effect of fracture surface morphology on the conductivity of propped fractures, and also help to establish a laboratory model of the conductivity of rough fractures.

Influence of the Metal Surface Texture on the Possibility of Controlling the Phase Transition of Water Droplets in the Single-Phase Regime

We experimentally studied the influence of the texture of copper and steel surfaces on the possibility of controlling the phase transition of water droplets in the single-phase regime. The texture of metals was formed by polishing and grinding, which corresponded to the finishing treatment of heat transfer surfaces in cooling systems for energy-saturated equipment. The samples were studied by microscopy and profilometry. The texture was estimated by three-dimensional roughness parameters. It was found that, with a 2–2.5-fold increase in roughness, the wetting of copper deteriorates (the contact angle increases from 66° to 93°), whereas the wetting of steel improves (the contact angle decreases from 89° to 71°). It was experimentally proven that, among the two main factors that affect the spreading diameter (wetting and roughness), wetting is the most significant. A hypothesis was formulated regarding the reason for the increase in the contact angle of 7–10° and the drop in the decrease rate of the contact diameter during the transition from the pinning to the mixed stage of droplet evaporation. It was found that an increase in the surface area of 0.1% leads to an increase in the total droplet evaporation rate of 4–6.5%.

Evaluation of Three-Dimensional Surface Roughness in Microgroove Based on Bidimensional Empirical Mode Decomposition.

Micromilling is an extremely important advanced manufacturing technology in the micromanufacturing industry. Compared with the traditional milling process, micromilling has stricter requirements on the surface roughness of the workpiece, and the roughness of the microcurved surface is not easy to measure. In order to more accurately characterize the curved surface morphology of the microgrooves obtained by micromilling, this paper proposes a method to extract the reference plane of the curved surface based on the bidimensional empirical mode decomposition algorithm and characterize the three-dimensional surface roughness of the curved surface. First, we synthesize the morphologies of the microgrooves by simulated non-Gaussian rough surfaces and models of textures. Second, the bidimensional empirical mode decomposition algorithm was used to extract the reference planes of the simulated microgrooves. Third, the three-dimensional roughness parameters suitable for the curved surfaces of microgrooves were selected to establish an evaluation system. The results show that the mean squared errors of the reference planes are below 1%, so bidimensional empirical mode decomposition can effectively extract reference planes, and the evaluation system of three-dimensional surface roughness proposed in this paper reflects morphological characteristics of the curved surfaces of microgrooves more thoroughly than that of two-dimensional surface roughness parameters.

Study on sensitivity analysis of tooth surface roughness parameters and contact stress

The reasonable selection of three-dimensional roughness parameters can evaluate the service performance of the machined surface, and its excessively high dimension greatly increases the difficulty of selection. In order to reveal the correlation law between the 3D roughness parameters and the tooth surface contact performance parameters, the correlation analysis theory is used to explore the correlation, and the nonlinear mapping model is constructed by using the BP neural network, the genetic algorithm optimization and Morris and Sobol′ two global sensitivity. The qualitative analysis method conducts the qualitative and quantitative analysis of each parameter, selects the three-dimensional roughness parameters that have the greatest impact on the contact performance of the tooth surface, and determines the primary and secondary relationship, solves the problem of parameter redundancy, and provides the theoretical basis for the anti-fatigue design and manufacturing of the tooth surface. The results show that the overall influence of the maximum shear stress on the gear tooth contact and the maximum surface pressure are arranged in the following order: the arithmetic average height (Sa) and the peak volume (Vmp), in which Sa has a strong correlation.

Analysis of the texture direction of the milled surface on the wear resistance of the workpiece

Wear is an important cause of surface failure and material loss of the workpiece. This paper analyzed the influence of different texture directions on the wear resistance of the workpiece produced by the ball-end milling surface. Firstly, the surface topography formed by the ball-end milling was established. Based on the Archard wear model, the Fortran language was used to write subroutines, and the Adaptive-Lagrange Euler (ALE) meshing technology of the Umeshmotion module was applied in the simulation software ABAQUS to establish a new wear simulation model; Secondly, the wear mechanism was analyzed based on factors such as contact pressure, contact area and wear amount, and the best wear-resistant texture direction was obtained; Finally, the wear resistance of the surface was analyzed according to the three-dimensional roughness parameters, the three-dimensional roughness parameters that have a greater influence on the wear resistance of the milling surface were chosen, and used the three-dimensional roughness parameters to establish the prediction model of the milling surface texture on the wear amount. This paper provides a new method for predicting the wear amount of milling topography by using three-dimensional roughness parameters. The result is of great significance for selecting reasonable milling parameters and improving the wear resistance of the workpiece surface.

Research on Peak Shear Strength Criterion of Rock Joints Based on the Evolution of Dilation Angle

The surface morphology of joints directly determines the contact area and peak shear strength of rock in shearing. This research gives a detailed description of the three-dimensional roughness parameters proposed by Grasselli, and discusses the morphology characteristics of the roughness parameter C in different ranges. Quoting Xia's direct shear test data, the relationship of peak shear strength, peak shear strength/normal stress, residual strength, dilation with roughness and normal stress are studied. The deficiencies in the previous classical criteria are explained in detail. A new peak shear strength criterion is established based on the boundary conditions of the dilation angle. The nonlinear characteristic of peak shear strength is included in the peak dilation angel, so that the new criterion satisfies the Mohr–Coulomb law of nonlinear form. In the expression of the initial dilation angle, the new criterion satisfies the fact that the peak shear strength decreases after once sheared. Finally, the test data of Grasselli and Yang are used to compare the prediction accuracy of Grasselli’s criterion, Yang’s criterion, Xia’s criterion and the new criterion. In general, the new criterion has the highest degree of agreement with the test results.

Experimental study on friction coefficient and temperature rise of heavy-load grease-lubricated spherical plain bearings with surface texture

Purpose This paper aims to improve the tribological performance of grease-lubricated spherical plain bearings (SPBs) under heavy load, dimple-type textures were prepared by laser on the outer surface of the inner ring. The influence of roughness parameters of a textured surface on reducing friction coefficient and temperature rise was also explored. Design/methodology/approach This study adopts a laser processing method to fabricate dimple-type textures. Three-dimensional roughness parameters were used to characterize the textured surfaces. The friction coefficients of five SPBs with surface texture and one original commercially available SPB without surface texture under different nominal loads were measured on a self-established test rig. The data of temperature rise were obtained by nine embedded thermal couples. Findings The results indicate that SPBs with textures generally exhibit lower friction coefficients than the original SPB without textures. The dimple depth has a significant influence on improving the tribological performance, which coincides with the analysis by surface roughness parameters. A textured surface with negative Ssk and high Vvc has the minimum temperature rise. Originality/value As it is too difficult to arrange sensors into heavy-load SPBs, there are few reports about the temperature characteristics. Through nine embedded thermal couples, the distribution of temperature rise on the inner ring of SPBs was given in this study. The positive effect of surface texture on reducing temperature rise and friction coefficient was verified, which is beneficial for the design of heavy-load SPBs.

Correlation of Three-Dimensional Roughness Parameters With the Crater Dimensions in μED-Milling of Cryogenic-Treated Tool and Workpiece

Abstract Microfluidics is one of the rapidly growing markets in the present era of miniaturization. Microchannels have wide applications in various fields such as biomedical, mechanical, electrical, and chemical sciences. Machining microfeatures with high aspect ratio in metals is difficult by mechanical and lithography-based processes. Micro-electric discharge milling is a suitable process to machine microcavities and microchannels in all electrically conductive materials. The main disadvantage of this process is its very low material removal rate. Improving the machining performance of micro-electric discharge machining (μEDM) is a research area that attracts researchers and remains as an unfulfilled agenda. The aim of this study is to improve the machining performance of micro-electric discharge milling process by investigating the performance of cryogenically treated tool and workpiece materials. Since surface roughness determines the minimum feature size machinable by any micromachining process and also it is an important factor in determining the flow characteristics of microchannels, a detailed comparative study was conducted on the three-dimensional (3D) surface quality parameters along with machining performance while using all four different combinations of untreated and cryogenically treated tool and workpiece, and the roughness parameters are correlated with the erosion behavior. The study revealed significant change in material removal rate and erosion pattern due to cryogenic treatment.

Droplet Spreading and Wettability of Abrasive Processed Aluminum Alloy Surfaces

One of the main cause of a droplet metastable state is found to be surface roughness. This state is characterized by a large contact angle hysteresis and condition when the static contact angle is larger than the advancing dynamic contact angle. Besides the texture, other factors can influence the deviation from the equilibrium state, in particular, the fluid flow rate (the growth rate of a droplet) affecting the contact line speed. An experimental study was done to determine the effect of roughness and fluid flow rate on wetting of aluminum-magnesium alloy surfaces with random roughness processed by abrasive polishing. Three-dimensional roughness parameters were used to evaluate their texture. The correlations between these parameters, static, advancing and receding dynamic contact angles, hysteresis, and contact line speed were obtained. The molecular-kinetic theory of wetting was used to interpret the dynamic contact angle data.

Investigation of the Topography of Face Milled Surfaces

Effects of the changing of cutting on the two-and three-dimensional roughness parameters of surfaces machined by face milling are investigated in the paper. The focus is on how the changing of the ratio of the feed and depth of cut affects the generated surface topography and its parameters in the case of constant undeformed uncut chip cross-section. Additionally, it is demonstrated how setting errors of individual inserts affect the roughness parameters of machined surfaces.

3D profile filter algorithm based on parallel generalized B-spline approximating Gaussian

Currently, the approximation methods of the Gaussian filter by some other spline filters have been developed. However, these methods are only suitable for the study of one-dimensional filtering, when these methods are used for three-dimensional filtering, it is found that a rounding error and quantization error would be passed to the next in every part. In this paper, a new and high-precision implementation approach for Gaussian filter is described, which is suitable for three-dimensional reference filtering. Based on the theory of generalized B-spline function and the variational principle, the transmission characteristics of a digital filter can be changed through the sensitivity of the parameters (t1, t2), and which can also reduce the rounding error and quantization error by the filter in a parallel form instead of the cascade form. Finally, the approximation filter of Gaussian filter is obtained. In order to verify the feasibility of the new algorithm, the reference extraction of the conventional methods are also used and compared. The experiments are conducted on the measured optical surface, and the results show that the total calculation by the new algorithm only requires 0.07 s for 480×480 data points; the amplitude deviation between the reference of the parallel form filter and the Gaussian filter is smaller; the new method is closer to the characteristic of the Gaussian filter through the analysis of three-dimensional roughness parameters, comparing with the cascade generalized B-spline approximating Gaussian. So the new algorithm is also efficient and accurate for the implementation of Gaussian filter in the application of surface roughness measurement.

New criterion for rock joints based on three-dimensional roughness parameters

The shear behavior of rock joints is important in solving practical problems of rock mechanics. Three group rock joints with different morphologies are made by cement mortar material and a series of CNL (constant normal loading) shear tests are performed. The influences of the applied normal stress and joint morphology to its shear strength are analyzed. According to the experimental results, the peak dilatancy angle of rock joint decreases with increasing normal stress, but increases with increasing roughness. The shear strength increases with the increasing normal stress and the roughness of rock joint. It is observed that the modes of failure of asperities are tensile, pure shear, or a combination of both. It is suggested that the three-dimensional roughness parameters and the tensile strength are the appropriate parameter for describing the shear strength criterion. A new peak shear criterion is proposed which can be used to predict peak shear strength of rock joints. All the used parameters can be easily obtained by performing tests.

Surface Characteristic of Pure Titanium Sandblasted with Irregular Zirconia Particles and Acid-Etched

Irregular alumina (IAl2O3) is widely used in the procedure of sandblasting with large grit and acid-etching (SLA) which has been confirmed as a favorable surface treatment for implant to improve osseointegration. However, IAl2O3 with cytotoxic has been found residual on implant surfaces after modification and thought to be a potential threaten to implants’ long-term survival. Due to its similar shape and excellent biocompatibility, irregular zirconia (IZrO2) was used as sandblast particle in the present study to compare the different characteristic between IZrO2SLA and IAl2O3SLA surfaces. SEM, optical profilometry and XRF analysis were performed for comparison of surface characteristic. Combined with acid-etching, IZrO2 could generate suitable primary and secondary roughness with, respectively, 10­30µm pits and 1­3µm micro pits. Three-dimensional roughness parameters (Sa, Sz, Sdr and Sds) revealed that because of the lower Vickers hardness and higher Specific gravity of IZrO2, IZrO2SLA surface was less rough than IAl2O3SLA surface. Meanwhile, resulted from its different physical properties, IZrO2 (0.13 « 0.07%) was detected significantly less on IZrO2SLA surface than IAl2O3 (6.74 « 0.74%) on IAl2O3SLA surface. Therefore, IZrO2SLA could easily prepare titanium surface with suitable multi-level morphology and moderate roughness for osseointegration. Furthermore, fewer sandblast particles residual on IZrO2SLA surface, worries from harmful residue could be greatly reduced due to the biocompatibility of IZrO2. [doi:10.2320/matertrans.M2011291]

The variability of functional and amplitude three-dimensional roughness parameters for electron-beam and electro-discharged textured surfaces

Stylus profilometry has been used for many years to measure surface finish. A stylus is drawn across a surface creating an x-y data set. A range of 2D surface parameters can be calculated. Measurements are now possible using 3D technology by raster scanning a stylus across a surface. This creates an x-y-z data set. Although various 3D parameters can be calculated, there is currently no 3D standard for parameters whereas there are 2D standards. Many studies of 2D parameters, their usefulness and reliability have been published but as yet there has been little work done on 3D parameters. This project seeks to redress the balance by presenting the results of a study into 3D parameters and their reliability. Raster-scan measurements have been made on a variety of different surfaces and at a variety of points within the surfaces. The paper reports on the stability and variability of the measurements.

Holographic contouring for determination of three-dimensional description of surface roughness

An optical full field method for automatic determination of roughness parameters was elaborated. An experimental set-up for registration of interference fringes, which are consecutive profilograms in direction perpendicular to the lay was presented. The set of profilograms registered by CCD (charge-coupled-device) camera is the source data for algorithms calculating two and three-dimensional roughness parameters and three-dimensional geometry of the surface. The result of optical measurements of grinding surface was compared with roughness parameters obtained by Talysurf 5.

Investigation on the Surface Topography in Polishing Using Atomic Force Microscopy

An investigation was carried out on the surface topography generation in polishing. Hardened tool steel specimens were polished using different parameters and the surface topography was examined using an Atomic Force Microscope (AFM). Measurements using AFM were initially compared to measurements obtained with a stylus instrument and with an optical profilometer. Contour plots were produced and a number of three-dimensional roughness parameters calculated for each surface. A statistical analysis of the results pointed out the most critical parameter with respect to all roughness parameters, for the material and hardness considered in this investigation, to be the grain size. The process parameters polishing cloth, lubricant, speed and pressure were found to have varying statistical significance with respect to the different roughness parameters. The roughness parameters Sa and Sk were found to be good indicators of the effect of varying the process parameters. An investigation was subsequently carried out on the surface topography generation as a function of the polishing time, for different grain sizes. Good reproducibility of the roughness parameters was found in two different specimens series. Most of the parameters' decrease takes place during the first 100-200 seconds of polishing.

Roughness Parameters of Surfaces by Atomic Force Microscopy

We present a standardized measurement report for surfaces investigated by scanning probe microscopy (SPM), which include twenty three-dimensional roughness parameters to characterize the surface topography. The examples are some polished copper samples and the scan size is 5 μm × 5 μm. Some of the parameters are generalizations of two-dimensional standards, and some are three-dimensional parameters normally used at larger scan sizes (mm × mm). Furthermore, there are some newly developed parameters extracted from Fourier analysis that reflect the directionality of surface texture. The parameters are discussed and it is shown that not all parameters are giving meaningfully information on μm-range scans.