3D Roughness Research Articles

Experimental study of roughness spectrum of sandy seafloor with an underwater laser 3D scanning system

To measure and characterize the roughness spectrum of sea-bottom, which is an important input parameter of the bottom acoustic backscattering model, an underwater laser three-dimensional (3D) scanning system for measuring seafloor microtopography has been developed successfully. The proposed underwater laser 3D scanning system can provide 3D seafloor microtopography with the resolution of millimeter levels in both horizontal and vertical directions and obtain the roughness spectrum of sea-bottom further. Two sets of data, which were suitable to model low- and mid-frequency acoustic backscattering at 6–24 kHz, were collected in two sites of sandy bottom during the acoustic scattering experiment in the southern Yellow Sea. The one-dimensional (1D) and two-dimensional (2D) roughness spectrum of the seafloor have been calculated at the two sites named S1 and S2, respectively. The result shows that calculated 2D spectral indices and spectral intensities, respectively, were 3.45 and 2.17 × 10−4 m4 at S1 and 3.33 and 4.66 × 10−4 m4 at S2. 2 D roughness spectrum parameters were used to model the acoustic scattering at S1, and the result indicates that the measurement results of the seafloor roughness spectrum is suitable for modeling bottom acoustic scattering.

Grinding performance oriented experimental evaluation on TiC-Steel cermet with vitrified bond cBN wheel

TiC-Steel cermet is widely used in aerospace and mining machinery owing to its excellent performance. However, the high wear resistance and the heterogeneity make its machining a challenging task. To investigate the grinding performance of TiC-Steel cermet, vitrified bond cBN wheel was customized to conduct dry grinding experiments. Grinding force was measured using a Kistler dynamometer; surface topography and 3D surface roughness parameters were measured by laser microscopy and scanning electron microscopy. Results indicate that plastic removal of steel phase, brittle fracture of ceramic phase, ceramic phase wear, ceramic phase debonding and microcracks are main removal modes of TiC-Steel cermet. 3D surface roughness parameters S a , S q , and S z consistently increase with increasing grinding depths from 25 μm to 125 μm and decrease with increasing spindle rotation speed. Effect of feed rate on the 3D surface roughness parameters is less than that of the grinding depth. The trend of the grinding force and surface topography is similar to that of 3D surface roughness parameters. Hence, the optimal processing parameters ( v w = 1–2 m/min, a p = 25 μm, n s = 5130 rpm) were used to obtain the best surface quality and the lowest grinding force (the minimum F N and F T of 9.2 N and 3.5 N, respectively). This study is devoted to broaden the research on the machinability of carbide-based cermets and promote utilization rate of cermets in industry.

A numerical and experimental investigation on the evolution of three-dimensional surface topography of 12Cr2Ni4A steel in shot peening

Shot peening is widely used as a surface strengthening technology as it can enhance fatigue life of mechanical components by introducing reasonably distributed compressive residual stress. However, improper selection of processing parameters would inevitably lead to deterioration of the surface quality, and negatively affect on the fatigue performance. In this paper, a random multiple-shot model was proposed to accurately calculate the evolution of 3D surface topography 12Cr2Ni4A steels during shot peening. The simulated results are in good agreement with the experimental results, with an error of less than 10%. It is found that surface roughness parameter Sa first increases significantly and then decreases slowly with the increase of peening time. Moreover, the surface height after shot peening obeys a normal distribution and the 3D surface roughness is positively correlated with the initial roughness.

Application of 3D Roughness Parameters for Wear Intensity Calculations

Abstract In this paper, calculations of 3D parameter Vm (material volume) of surfaces with irregular roughness and comparison with experimental data were performed, with further application of this parameter in calculations of wear intensity. First, using Mountains Map software for profilometric measurements, 3D roughness processing and determination of material volume Vm at specific relative levels γ were performed. The next step was an additional analysis of the distribution of surface ordinates using a theoretical and experimental Laplace function. The given check confirmed that for mostly surfaces with irregular roughness the ordinate distribution corresponds to the normal Gaussian distribution law, but in cases when the asymmetry of the ordinate distribution function goes outside the permissible limits (|∆Ssk|> 10%), errors> 10 % occur. On this basis, the mathematical formula of the material volume Vm was derived, and the obtained calculations were compared with the measured values. The results showed that the calculated values of the parameter Vm were very close to the experimental data (|∆Vm|<10 %), while at the relative level γ=+3, errors occurred that was related to the deviation from the normal distribution law. It was concluded that the given parameter could be used in the calculations of linear wear intensity, knowing the relative level γ.

Understanding the surface integrity of laser surface engineered tungsten carbide

The study investigated the effect of fibre laser processing (1060 nm, 240-ns pulse duration) on the surface integrity of tungsten carbide (WC). The induced surface damage ranged from crack formation, porosity, balling, to spherical pores; the severity and presence of each were dependent on the laser parameters selected. The influence of fluence (0.05–0.20 J/cm2), frequency (5–100 kHz), feed speed (250–2500 mm/s) and hatch distance (0.02–0.06 mm) on 2D and 3D surface roughness were analysed using the Taguchi technique. Fluence, frequency, and the interaction effect of these were the most influential factors on the surface integrity; from this a linear model was generated to predict the surface roughness. The model performed best at moderate to medium level of processing with an error between 1 and 10 %. The model failed to predict the material response as accurately at higher fluences with percentage errors between 15 and 36 %. In this study, a crack classification system and crack density variable were introduced to estimate the number of cracks and crack type within a 1-mm2 area size. Statistical analysis of variance (ANOVA) found that fluence (63.49%) and frequency (29.38%) had a significant effect on the crack density independently but not the interaction of both. The crack density was minimised at 0.149 J/cm2 and 52.5 kHz. To the author’s knowledge, for the first time, a quantitative analysis of the crack formation mechanism for brittle materials is proposed (post laser processing).

Interparticle Adhesion Regulates the Surface Roughness of Growing Dense Three-Dimensional Active Particle Aggregates.

Activity and self-generated motion are fundamental features observed in many living and nonliving systems. Given that interparticle adhesive forces can regulate particle dynamics, we investigate how interparticle adhesion strength controls the boundary growth and roughness of active particle aggregates. Using particle based simulations incorporating both activity (birth, death, and growth) and systematic physical interactions (elasticity and adhesion), we establish that interparticle adhesion strength (fad) controls the surface roughness of a densely packed three-dimensional(3D) active particle aggregate expanding into a highly viscous medium. We discover that the surface roughness of a 3D active particle aggregate increases in proportion to the interparticle adhesion strength (fad) and show that asymmetry in the radial and transverse active particle mean-squared displacement (MSD) suppresses 3D surface roughness at lower adhesion strengths. By analyzing the statistical properties of particle displacements at the aggregate periphery, we determine that the 3D surface roughness is driven by the movement of active particle toward the core at high interparticle adhesion strengths. Our results elucidate the physics controlling the expansion of adhesive 3D active particle collectives into a highly viscous medium, with implications into understanding stochastic interface growth in active matter systems characterized by self-generation of particles.

Effect of Temperature on Electrochemically Assisted Deposition and Bioactivity of CaP Coatings on CpTi Grade 4.

Calcium phosphate (CaP) coatings are able to improve the osseointegration process due to their chemical composition similar to that of bone tissues. Among the methods of producing CaP coatings, the electrochemically assisted deposition (ECAD) is particularly important due to high repeatability and the possibility of deposition at room temperature and neutral pH, which allows for the co-deposition of inorganic and organic components. In this work, the ECAD of CaP coatings from an acetate bath with a Ca:P ratio of 1.67, was developed. The effect of the ECAD conditions on CaP coatings deposited on commercially pure titanium grade 4 (CpTi G4) subjected to sandblasting and autoclaving was presented. The physicochemical characteristics of the ECAD-derived coatings was carried out using SEM, EDS, FTIR, 2D roughness profiles, and amplitude sensitive eddy current method. It was showed that amorphous calcium phosphate (ACP) coatings can be obtained at a potential −1.5 to −10 V for 10 to 60 min at 20 to 70 °C. The thickness and surface roughness of the ACP coatings were an increasing function of potential, time, and temperature. The obtained ACP coatings are a precursor in the process of apatite formation in a simulated body fluid. The optimal ACP coating for use in dentistry was deposited at a potential of −3 V for 30 min at 20 °C.

Multiscale Three-Dimensional Morphological Characterization of Calcareous Sand Particles Using Spherical Harmonic Analysis

Particle morphology is a fundamental inherent property that substantially affects the macroscopic behavior of granular materials. The division and separation of particle morphology at different scale levels contributes to the further multiscale morphology related orthogonal researches. In this context, the high-resolution X-ray micro-computed tomographic (X-CT) scanning and spherical harmonic (SH) analysis were combined to complete the precise and digitized reconstruction of sand particles. The 3D sphericity, roundness and roughness were introduced to define the particle morphology at three scale levels (the general shape, local angularity and surface textures). Two typical sand particles, Calcareous sand (CS) and Fujian sand (FS), were tested in this study. The results showed that the irregularity, angularity and roughness of CS is higher than that of FS, and the multiscale morphological features of the two types of natural sand were given and compared digitally.

The physical meaning of Grasselli's morphology parameters and its correlations with several other 2D fracture roughness parameters

Grasselli's 2D morphology parameter θ max ∗ / ( C + 1 ) 2 D has been widely used in rock engineering. However, the physical meaning of θ max ∗ / ( C + 1 ) 2 D is not clear, and the calculation is complex and time-consuming. By introducing a density function to characterize the distribution of the inclination, this study found that the physical meaning of θ max ∗ / ( C + 1 ) 2 D is the expected value of the inclination facing the shear direction. Based on this finding, this study found that θ max ∗ / ( C + 1 ) 2 D can be simplified as a statistical parameter. Besides, several new 2D roughness metrics expressed in discrete form were proposed. These new roughness metrics have clear physical meanings and can be obtained easily. This study found that two kinds of weight can be employed to calculate the average inclination facing the shear direction. Besides, this study found several generalized equivalent relationships among some 2D roughness metrics.

Effect of Aggregate Roughness on Strength and Permeation Characteristics of Lightweight Aggregate Concrete

This paper aims to examine the effect of surface roughness of lightweight aggregate particles (LWA) on the strength and permeation characteristics of lightweight aggregate concrete (LWAC). Changing the smooth surface texture of LWA particles was achieved by applying surface polishing to make rough texture of the aggregate particle surface. LWAC mixes with different LWA surface roughness (smooth and rough) were produced, and their strength and permeation properties were investigated. Cut section method was adopted to measure the surface roughness of LWA particles. The surface profile was measured by using ImageJ software on images captured using the optical microscope (OM) and scanning electron microscope (SEM) with different magnifications. The ability of making the surface of LWA particles rough by polishing them was proved by means of 2D roughness measurements. From the results, it was found that using treated LWA with rough surface helped in enhancing the strength (compressive) and the permeation properties (water absorption and sorptivity) of lightweight aggregate concrete (LWAC). Making the LWA rough helped in improving the compressive strength by about 13.5% owing to enhancing the ITZ between the LWA particles and the cement paste as well as improving the chemical bonding and mechanical interlocking forces between them. In addition, using rough lightweight aggregate led to reduce the water absorption and cumulative volume of water absorbed by about 9% and 12%, respectively, compared to values of mix with original (smooth) LWA.

Multifunctional 3D cationic starch/nanofibrillated cellulose/silver nanoparticles nanocomposite cryogel: Synthesis, adsorption, and antibacterial characteristics

We report a new 3D nanocomposite cryogel combines the advantages of cationic starch (Cs), nanofibrillated cellulose (NFC) and silver nanoparticles (Ag NPs). Cs was the main component of the cryogel while NFC was used as a filling agent to enhance the mechanical properties of the produced cryogel. Both Cs and NFC endow the cryogel with adsorption properties while Ag NPs enhances its antibacterial properties. Ag NPs was green synthesized with the aid of microwave radiation using NFC as reducing and stabilizing agent. The prepared Ag particles were free of impurities with sizes <10 nm and good stability in solution. Two different concentrations of the prepared Ag NPs were added to a mixture of Cs and NFC and subjected to freeze drying to get porous cryogel (3D microstructure). The Ag NPs free cryogel has highly porosity smooth surface with large surface area. Adding Ag NPs decreased these features and increased the 3D roughness. Optimum adsorption of reactive blue 49 was observed after 30 min of contact with 1.5 g/L of the cryogel at pH 1. The adsorption kinetics and isotherm were best described by the pseudo-first-order and Freundlich equations, respectively. All prepared cryogels have notable antibacterial properties that were significantly improved by adding Ag NPs. Overall, the new 3D composite cryogel can efficiently remove dyes and bacteria from wastewater.

Photogrammetry based characterization of hydro-mechanical properties of a rock fracture

Hydro-mechanical properties of a single fracture are governed by several parameters such as contact area, roughness, tortuosity, aperture, channeling, matedness, sample sizes, normal stress, flow regime, and flow boundary conditions. In this study, photogrammetry with numerical modeling and laboratory measurements were used to investigate the influences of roughness, normal stress, aperture, water pressure, and different flow boundary conditions on fluid flow in an artificial granite fracture. A Finnish Kuru grey granite block was mechanically split, and a 250 mm × 250 mm × 100 mm slab pair sample with a tensile crack in the middle was extracted. A photogrammetry-based method was used to reconstruct a 3D model of the fracture geometry. The resulting model was numerically simulated with COMSOL using the Navier-Stokes equations. Fluid flow experiments were computed with the Forchheimer equation. Comparison between the numerical modeling results and the analytical solution confirms that the 3D roughness geometry has a crucial role in defining the transmissivity, especially for nonlinear flow. On the other hand, normal stress increases fracture closure and increases contact areas, decreasing the hydraulic aperture and changing the flow paths. The presented method can be used in the contactless estimation of fluid flow properties of rock joints.

Effects of localized blowing on the turbulent boundary layer over 2D roughness

Effects of localized blowing on the turbulent boundary layer over 2D roughness

Measuring dimensional and morphological heat alterations of dismemberment-related toolmarks with an optical roughness metre.

This experimental study provides a further understanding of the post-burning nature of sharp force trauma. The main objective is to analyse the distortion that fire may inflict on the length, width, roughness, and floor shape morphology of toolmarks induced by four different implements. To this end, four fresh juvenile pig long bones were cut with a bread knife, a serrated knife, a butcher machete, and a saw. A total of 120 toolmarks were induced and the bone samples were thus burnt in a chamber furnace. The lesions were analysed with a 3D optical surface roughness metre before and after the burning process. Afterwards, descriptive statistics and correlation tests (Student's t-test and analysis of variance) were performed. The results show that fire exposure can distort the signatures of sharp force trauma, but they remain recognisable and identifiable. The length decreased in size and the roughness increased in a consistent manner. The width did not vary for the saw, serrated knife, or machete toolmarks, while the bread knife lesions slightly shrunk. The floor shape morphology varied after burning, and this change became more noticeable for the three knives. It was also observed that the metrics of the serrated knife and machete cut marks showed no significant variations. Our results demonstrate that there is a variation in the toolmark characteristics after burning. This distortion is dependent on multiple factors that influence their dimensional and morphological changes, and the preservation of class features is directly reliant upon the weapon employed, the trauma caused, and the burning process conditions.

Focus on lasers, imaging, microscopy, and nanoscience

Focus on lasers, imaging, microscopy, and nanoscience

Study of distributed suction of the boundary layer influencing the flow past a 3D roughness element on a straight wing model

Study of distributed suction of the boundary layer influencing the flow past a 3D roughness element on a straight wing model

TRIBOLOGY AND TOPOGRAPHY OF HARD MACHINED SURFACES

In machining automotive industrial parts by hard machining procedures, the topographic characteristics of high accuracy surfaces have high importance. In this paper 2D and 3D surface roughness features of gear bores machined by hard turning and grinding are demonstrated. The 3D roughness parameters, which are considered as more exact than the 2D parameters, were compared to the 2D ones, which are used more widely in industrial practice. The analyzed machining procedure versions were ranked based on the topographic parameters determining the tribological (wear and oil-retention capability) characteristics of the different surfaces.

Surface Roughness Evaluation in Thin EN AW-6086-T6 Alloy Plates after Face Milling Process with Different Strategies.

Lightweight alloys made from aluminium are used to manufacture cars, trains and planes. The main parts most often manufactured from thin sheets requiring the use of milling in the manufacturing process are front panels for control systems, housing parts for electrical and electronic components. As a result of the final phase of the manufacturing process, cold rolling, residual stresses remain in the surface layers, which can influence the cutting processes carried out on these materials. The main aim of this study was to verify whether the strategy of removing the outer material layers of aluminium alloy sheets affects the surface roughness after the face milling process. EN AW-6082-T6 aluminium alloy thin plates with three different thicknesses and with two directions relative to the cold rolling process direction (longitudinal and transverse) were analysed. Three different strategies for removing the outer layers of the material by face milling were considered. Noticeable differences in surface roughness 2D and 3D parameters were found among all machining strategies and for both rolling directions, but these differences were not statistically significant. The lowest values of Ra = 0.34 µm were measured for the S#3 strategy, which asymmetrically removed material from both sides of the plate (main and back), for an 8-mm-thick plate in the transverse rolling direction. The highest values of Ra = 0.48 µm were measured for a 6-mm-thick plate milled with the S#2 strategy, which symmetrically removed material from both sides of the plate, in the longitudinal rolling direction. However, the position of the face cutter axis during the machining process was observed to have a significant effect on the surface roughness. A higher surface roughness was measured in the areas of the tool point transition from the up-milling direction to the down-milling direction (tool axis path) for all analysed strategies (Ra = 0.63–0.68 µm). The best values were obtained for the up-milling direction, but in the area of the smooth execution of the process (Ra = 0.26–0.29 µm), not in the area of the blade entry into the material. A similar relationship was obtained for analysed medians of the arithmetic mean height (Sa) and the root-mean-square height (Sq). However, in the case of the S#3 strategy, the spreads of results were the lowest.

Analysis of Surface Roughness and Three-dimensional Scanning Topography of Zirconia Implants before and after Photofunctionalization by Atomic Force Microscopy: An In Vitro Study.

Aim:To analyze surface roughness and three-dimensional (3D) scanning topography parameters of zirconia implants before and after photofunctionalization by atomic force microscopy (AFM).Materials and Methods:Ten commercially available zirconia implants five each in the study and control group were taken. The study group was subjected to ultraviolet (UV) radiation for 48 h using the shorter wavelength of 254 nm. After washing all the implants with 70% alcohol and drying, 3D surface topography and roughness parameters were analyzed using CSC 17 probe AFM at three different magnifications 25 μm, 50 μm, and 80 μm, respectively.Results:The surface topography and calculated mean amplitude, spatial, and hybrid parameters of the study group were higher than the control group (P < 0.05) in all three magnifications. Up to scale depth and peak value for the study and control group were (−0.4–0.4: −2-1) (−0.75 to 0.6:−1–1.3) (−0.75-−0.5: −1.5-1.3) for the study and control group at 25, 50, and 80 μm magnification, respectively. This indicates that photofunctionalization increased surface roughness of Zirconia implants to desirable extent.Conclusion:There is a definite difference in the quantitative topographic characteristics with zirconia implants being microroughned after photofunctionalization (UV treatment).

Process optimization of high-speed dry milling UD-CF/PEEK laminates using GA-BP neural network

High-performance carbon fiber-reinforced polyetheretherketone (CF/PEEK) is widely used in aerospace and premium-end medical fields due to its high strength-weight ratio, shock resistance, and reusability. However, its dry machining requirement is a significant limit to improving machining efficiency and machining quality using a traditional process. Addressing this issue, the high-speed dry (HSD) machining technique is imported in this paper. Multi-level mixed orthogonal experiments of dry milling unidirectional (UD) CF/PEEK laminates with the fiber orientation of 0° and 90° are designed. Aiming at quantitative characterizing surface quality, three-dimensional (3D) surface roughness Sq and 3D fractal dimension Ds are used to present surface roughness and surface defects, respectively. A characterization system for surface defects generated in milling CRF/PEEK is proposed. A prediction model of surface quality considering fiber orientation, cutting speed, feed per tooth, and cutting width is then established using the genetic algorithm optimized BP (GA-BP) neural network. The prediction results show that the model is of acceptable generalization capability with a prediction accuracy of over 90.39%. Based on the analysis of surface qualities and cutting temperatures, the HSD machining technique is verified to be feasible in milling UD-CF/PEEK, and the recommended cutting speed in the HSD milling boundary is 1500–1600 m/min. The 3D fractal dimension is verified feasible to evaluate the size of complex surface defects of the machined UD-CF/PEEK. It has a non-rigid negative correlation with Sq in general. Besides, cutting speed and fiber orientation are the key factors affecting the machined surface microstructural characteristics. The present study gives technical references for improving surface quality in HSD milling CF/PEEK.