Initial Roughness Research Articles

Stabilization of roughness parameters of rolls of temper mill during idle running in stand

The main results of improving in the condition of the surface layer of the working rolls of the training mill with their joint rotation pressed against each other in a state without a trained strip, are considered in order to further minimize changes in the roughness parameters of the trained strip from roll to roll. The analysis of changes in the roughness parameters of the working rolls during their running-in as a result of the elastic-plastic interaction of the microsteps of their surfaces is carried out. Mathematical dependences are obtained for calculating of the roughness parameters of the working rolls during their idle running in the stand, taking into account the ergodicity function of the process. It is shown that the permissible degree of reduction of the height parameters of the rough layer of the working rolls before stabilization during their running is determined by contact loads, physical and mechanical properties of the material of the rolls, the initial parameters of the microgeometry of their surfaces and friction conditions, and the time to stabilize of the roughness parameters depends mainly on the contact load and the speed of running-in, decreasing with decreasing load and increasing speed. It is determined that the maximum possible reduction in the initial roughness of the roll treated with shot after idle running them in a stand with a coefficient of friction of 0.3 is on average 57 %. A further change in roughness is associated with the effect of wear of the rough layer during the training of a cold-rolled strip. The obtained mathematical dependencies allow you to assign processing parameters, such as the compression force of the rolls, the speed or at a given speed — the running-in time.

Magnetism-enhanced biomaterial Mg guide wire by MAP process for development of catheter insertion

The surface topography of implant tools has indicated an interfacial contact in degradation still being discovered; however, the glossy texture of a tiny magnesium wire is important for absorbable medical devices. This paper investigated the alterations of surface quality by a magnetic abrasive polishing method using a rotational magnetic field-assisted system with input parameters of revolution, abrasive media, magnetic pole, flux density, vibration, and amplitude that could noticeably enhance asperities along a sample. Furthermore, the blood flow simulation is used to analyze flow within blood vessels while maintaining the surface roughness conditions of the guide wire. The results are compared and discussed. Magnetic field simulation is employed to investigate the magnetic field strength in the polishing zone. Scanning Electron Microscopy (SEM) provides visual aids for recognizing the differences between pre-and post-workpieces of magnesium wire. The experimental results reveal that a wire diameter of 0.50 mm predominantly achieves surface morphology from the initial roughness of 0.22 μm to 0.05 μm. The results corroborate that the distribution of blood in the circulatory system was relatively stable. Hence, this study establishes a crucial benchmark for the precision polishing of ultra-thin magnesium wires, which is vital for their use as high-precision biodegradable medical devices.

Експериментальні дослідження електросуперфінішного оброблення сфокусованим струмом високоточних деталей авіаційного виробництва

The object of this study is the electrochemical superfinishing of high-precision aerospace assembly components (aircraft parts) by focusing on the current. The goal is to reduce the surface and edge roughness of high-precision parts of the spool valve type in a short time (up to 10-11 minutes) by implementing the principles of superfinishing along with electrochemical processes. The task: to conduct an experiment on the simultaneous processing of all the surfaces, edges, and grooves of a test sample of a high-precision part of a spool valve type by the electrochemical superfinishing method with a focused current. Methods of research include empirical analysis of existing and widespread methods of superfinishing, full-scale experiments, and inspection. The following results were obtained. According to the analysis, it was found that there are two the most widespread operations: electrochemical processing with subsequent superfinishing of the turbine working blades and processing of holes of various shapes and sizes. It was also found that the large number of superfinishing process parameters complicates its use for complex processing of aerospace assembly components. The authors proposed an alternative method – electrochemical superfinishing, the peculiarity of which is the use of a focused current that acts directly along the part generatrix, while the part rotates at high speed around its longitudinal axis in an electrolyte. Full-scale experiments were carried out on the simultaneous processing of all surfaces, edges, and grooves of a high-precision part sample of the spool valve type by electrochemical superfinishing, and positive results were obtained: part surfaces and edges roughness was reduced. It was found that the roughness decreases more intensively during the first minute of processing, and a higher initial roughness reduces better than an initially smaller roughness. Conclusions. The scientific novelty of the obtained results is as follows: electrochemical superfinishing with a focused current has been approved on the samples of high-precision aerospace components of the spool valve type; rounding of edges, improved roughness, and removal of burrs were obtained. The proposed method of processing use is rational when there is a need for accuracy of the working surface diameters of 0.001 mm, and it can be the subject of further research.

Approximate symplectic approach for mistuned bladed disk dynamic problem

A blade disk system plays a crucial role in the energy conversion efficiency of turbomachinery. Generally, a bladed disk is designed as a tuned system, which implies that the dynamic behaviors of all the blades are identical. In practice, there are some differences between the blades, known as mistuning, that can result in localized vibration. Thus, in this study, an approximate symplectic method developed to reproduce the vibration localization in a mistuned bladed disk system, that can provide guidance for designing vibration control strategies for the system. Considering the morphological characteristics of the interface roughness and the dynamic/stickiness characteristics of the sliding joint surface, an improved dry friction model is established to describe the coupling effects between the blades. Considering the micro-dynamic behaviors of the multi-joint surfaces, the dynamic problem of the entire bladed disk system is formulated as a set of ordinary differential equations (ODEs). An approximate symplectic method is developed in the Hamiltonian framework to simulate the vibration of each blade in the mistuned bladed disk system. From the numerical results reported, the phenomenon of vibration localization in the mistuned bladed disk system is reproduced in the comparison with the results in the tuned bladed disk system. In addition, the influences of the initial positive pressure, contact angle, and roughness of the surfaces on the strength of the vibration localization are revealed in detail in the numerical simulations.

Real-time correction of channel-bed roughness and water level in river network hydrodynamic modeling for accurate forecasting

The accuracy and reliability of hydrodynamic models are sensitive to both hydraulic state variables and model parameters, particularly the bed roughness, while their simultaneous real-time corrections and corresponding effects still need to be well-established and understood. This paper presents a real-time data assimilation model that corrects channel-bed roughness and water level in a river network hydrodynamic model, ensuring its accuracy and reliability. Experiments and parameter analysis evaluated the effect of initial roughness and observation noise level on model performance. Correcting both roughness and water level improved filtering time and forecasting accuracy by up to 63% and 80%, respectively, compared to methods only correcting water level. The filtering time was reduced by 44–63%, and the water level forecasting RMSE decreased by up to 80%. Both models experienced increased filtering time and forecasting error as observation noise increased, but the proposed model had a lower increase. With accurate hydraulic state measurement (e.g., 0.005 m error), the model achieved negligible water level forecasting error after 7 h of data assimilation. The model's accuracy depended on the initial channel-bed roughness, and the algorithm enables real-time roughness correction, making it useful for flood forecasting.

Rolling contact fatigue failure mechanism of bearing steel on different surface roughness levels under heavy load

It is inherent knowledge that rolling contact fatigue (RCF) failure of subsurface-initiated spalls usually occur under optimum surface under heavy load. However, our previous work has revealed surface-initiated RCF failure mechanism under heavy load and initial high roughness surface. The formation of surface crack caused by RCF is a complicated phenomenon that is accompanied by surface morphology and lubrication condition, as well as stress distribution and microstructure evolution. To clarify the main failure mechanism, this study carried out systematic RCF tests with different surface roughness specimens and conducted characterization of superficial microstructure for specimens of pre-service and post-service by Focused Ion Beam (FIB). The results clearly suggest precursor of collapsed morphology and nanocrystalline layer are the main factor that causes the RCF life with high roughness is lower than that with low roughness. While the spalling failure initiating from low roughness surface under heavy load are strongly relied on surface plastic deformation. Two main plastic deformation mechanisms are conductive to formation of surface cracks: the micro-plastic deformation and the local severe plastic flow. A newly failure mechanism that spalling failure initiates from surface has been proposed to link surface roughness and microstructure evolution.

Performance of Selective Plated Copper Coatings on Stainless Steel 316L and Nickel Alloy Ni201: Microstructure, Microhardness, Wear Resistance, and Corrosion Resistance

This study investigates the properties and performance of selective plated copper coatings on stainless steel 316L and nickel alloy Ni201 substrates, using acidic and alkaline electrolyte solutions. The analysis encompasses surface microstructure, elemental distribution, microhardness, surface roughness, wear resistance, and corrosion resistance of the coatings. The results demonstrate that the selective plated copper coatings exhibit a uniform and continuous deposition, free from visible irregularities or structural imperfections. Notably, the alkaline copper coatings exhibit significantly higher microhardness values compared to the acidic coatings, irrespective of the substrate materials. Surface roughness measurements reveal an increase in roughness after wear testing for all coatings, with the alkaline coatings showing lower initial roughness values and superior wear resistance compared to the acidic coatings. Concerning corrosion resistance, the alkaline copper coatings display a higher susceptibility to corrosion compared to the acidic coatings. Generally, the findings underscore the effectiveness of the selective plating process in producing high-quality, uniform, and defect-free copper coatings on stainless steel and nickel alloy substrates.

Effect of running-in on the low-pressure tribological performance of valve plate pair in axial piston pumps

Axial piston pumps are widely used in tunnel boring machines with compact structures and high efficiency. The efficiency and lifetime heavily depend on the tribological performance of the pump's valve plate pair. The running-in process is crucial to the steady-state tribological performance of the valve plate pair and directly influences its friction coefficient and wear rate, etc. Axial piston pumps always run-in with different pressure and speed gradients, starting from low-pressure. However, the initial running-in conditions significantly affect the running-in process of the valve plate pair and their effects on tribological performance are unclear. In this paper, ring-on-block testing is conducted. Effects of the speed (500 r/min and 1500 r/min) and pressure (2 MPa, 5 MPa, and 7 MPa) at different initial roughness (Ra = 0.4 μm and 0.05 μm) on the running-in are investigated. The friction coefficient, running-in time, wear rate, and worn surface are compared. Results show that a higher speed and initial roughness can reduce the running-in time, while the larger pressure will increase the friction coefficient and its fluctuation amplitude. The wear mechanism during the running-in process is mainly abrasive wear, while the plastic deformation wear appears with low initial roughness.

New two-stage running-in process with particle effect in three-body lubrication

Running-in is essential for improving the performance and lifetime of a machine. This study proposed a two-stage running-in procedure based on the lubrication regime and nanoparticle effect to increase running-in efficiency; the method was verified using a disk-on-block experiment. The first stage involved wearing down the high peaks of the surface asperities in relatively severe mixed lubrication. The second stage was a mild wear process, in which the shape of the asperity peak was trimmed with soft CuO particles in three-body mixed lubrication. The CuO concentrations were divided into three concentration variations (0.1 wt%, 0.5 wt%, and 1.0 wt%) to investigate the effect of CuO concentration on the smoothing surface processes. The tribological parameters, including the surface roughness value, peak radius of asperity, plasticity index, adhesion index, real contact area, true friction power intensity (TFPI), and modified true friction power intensity (MTFPI) index, were investigated to evaluate the friction coefficient, wear, and anti-scuffing performance. The result after first stage showed that the surface roughness value decreased to similarly low values for the different initial roughness values. After the second stage of the trimming process, the asperity peak radius, contact angle, real contact area, plasticity index, and anti-scuffing improved considerably. The obvious reduction in the friction coefficient in the second stage was due to the decrease in ratchet friction, deformation, and plowing friction. These methods effectively enhanced the efficiency of the running-in process.

Novel Process Modeling of Magnetic-Field Assisted Finishing (MAF) with Rheological Properties

The performance of a magnetic-field-assisted finishing (MAF) process, an advanced surface finishing process, is severely affected by the rheological properties of an MAF brush. The yield stress and viscosity of the MAF brush, comprising iron particles and abrasives mixed in a liquid carrier medium, change depending on the brush’s constituents and the applied magnetic field, which in turn affect the material removal mechanism and the corresponding final surface roughness after the MAF. A series of experiments was conducted to delineate the effect of MAF processing conditions on the yield stress of the MAF brush. The experimental data were fitted into commonly used rheology models. The Herschel–Bulkley (HB) model was found to be the most suitable fit (lowest sum of square errors (SSE)) for the shear stress–shear rate data obtained from the rheology tests and used to calculate the yield stress of the MAF brush. Processing parameters, such as magnetic flux density, weight ratio of iron and abrasives, and abrasive (black ceramic in this study) size, with p-values of 0.031, 0.001 and 0.037, respectively, (each of them lower than the significance level of 0.05), were all found to be statistically significant parameters that affected the yield stress of the MAF brush. Yield stress increased with magnetic flux density and the weight ratio of iron to abrasives in MAF brush and decreased with abrasive size. A new process model, a rheology-integrated model (RM), was formulated using the yield stress data from HB model to determine the indentation depth of individual abrasives in the workpiece during the MAF process. The calculated indentation depth enabled us to predict the material removal rate (MRR) and the instantaneous surface roughness. The predicted MRR and surface roughness from the RM model were found to be a better fit with the experimental data than the pre-existing contact mechanics model (CMM) and wear model (WM) with a R2 of 0.91 for RM as compared to 0.76 and 0.78 for CMM and WM. Finally, the RM, under parametric variations, showed that MRR increases and roughness decreases as magnetic flux density, rotational speed, weight ratio of iron to abrasive particles in MAF brush, and initial roughness increase, and abrasive size decreases.

Roughness Test of Aluminum A5052 before and after Forming by SPIF Process

Single point incremental forming process, which is also known as SPIF, that forms from one direction. SPIF process was used for milling an aluminum metallic sheet. In this paper, an aluminum (A5052) sheet was formed in a conical shape by the SPIF process. The A5052 sheet was deformed by the computer numerical control (CNC) technology in the T60 series milling machine. The conical shape was deformed by the spiral toolpath in the T60 series milling machine. At the surface of the A5052, lubricant grease was continuously applied manually for reducing the friction generated due to milling. Also, for decreasing the tool rotational force friction on the A5052 sheet there was the use of lubricant. Moreover, 0.1mm step-down is used for the tool path because it takes more time for forming a metallic sheet, however, it deformed the sheet smoothly. The 0.5mm step-down g-code was extracted from fusion 360. Then the metallic sheet A5052 surface was compared before and after deformation. For testing a metallic sheet A5052 the formability parameter was analyzed in the experiment part. The experiment was performed to find the optimal smooth surface from the CNC milling machine. The initial roughness value and the microscopic image were presented in the investigational part. Likewise, the comparison of points for the highest and lowest rough point was further discussed and compared throughout the experiment.

Effect of staining layer on roughness after progressive wear of monolithic ceramics.

The aim of this study was to evaluate staining layer behavior applied to high-translucency zirconia (YZHT), feldspathic ceramics (FD), and zirconia-reinforced lithium silicate (ZLS) surfaces against different antagonists. Monolithic ceramic discs (n = 120) (ø 12 mm; thickness, 1.2 mm; ISO 6872) were obtained, 30 from YZHT and FD, and 60 from ZLS CAD/CAM blocks (staining layer applied before or after the crystallization procedure). The specimens were divided into 12 subgroups (n = 10) according to the antagonists: steatite, polymer-infiltrated ceramic, or zirconia. Mechanical cycling (1.5 × 104 cycles; 15 N; horizontal displacement, 6 mm; 1.7 Hz) and flexural strength tests (1 mm/min-1000 kg cell) were performed. The differences between final and initial roughnesses (Ra, Rz, and Rsm), the mass loss, and the flexural strength data were individually analyzed by two-way ANOVA and Tukey's test (α = 0.05). The roughnesses of all ceramics did not present a statistically significant difference before wear simulation: Ra (p = 0.3348), Rz (p = 0.5590), and Rsm (p = 0.5330). After the wear simulation, the Ra parameter was not affected by an interaction between ceramic and antagonist (p = 0.595). The Rz and Rsm parameters were affected only by the antagonist pistons (both, p = 0.000). The ceramics used in this study showed statistically significant differences in mass loss after the wear test (p < 0.0001). The additional firing (2 steps) of the ZLS2 led to a higher lost mass quantity. All ceramics presented similar initial roughnesses and similar roughnesses after the wear simulation. The zirconia antagonist showed better performance against ceramics with high crystalline content. It is clear that restorative materials must be carefully selected by dental practitioners according to indications, properties, and antagonists. The steatite antagonist, that is, an enamel analog, showed better performance against vitreous ceramics, while the zirconia antagonist showed better performance against ceramics with high crystalline content. Wear affects the surface roughnesses of the ceramics. Additional firing for the staining of the zirconia-reinforced lithium silicate ceramic led to a greater loss of mass.

Effects of in-office bleaching agents on polished and unpolished nanofilled resin composite

BackgroundThis study investigates the effects of in-office bleaching agents on the color change and surface roughness of nanofilled resin composite finished by various polishing procedures. MethodsThe authors made 108 specimens from nanofilled resin composite, and the finishing and polishing procedures were performed with either Sof-Lex (3M ESPE) or OneGloss (Shofu). The specimens were then immersed in tea or coffee solution for 1 week, after which in-office bleaching agents were applied (n = 9). After polishing and bleaching, the surface roughness was measured with a surface profilometer. The specimen color parameters were measured with the Commission Internationale de l’Eclairage L∗a∗b∗ system in 3 stages, namely after polishing, after staining, and at the end of the bleaching procedure. The total color changes (ΔEab∗) were calculated, and ΔEab∗ not exceeding 2.7 was considered a clinically acceptable threshold. ResultsThe highest initial roughness value was observed on surfaces polished with OneGloss. In all groups, the surface roughness increased significantly after bleaching. For the Sof-Lex group specimens stained in both tea and coffee solutions, bleaching agent Opalescence Boost (Ultradent) reduced the color change value to 2.7 or less after bleaching. ConclusionsIn-office bleaching agents increased surface roughness in all groups, especially on unpolished surfaces. However, surface roughness was at an acceptable threshold for the multistep polished group, Sof-Lex, after bleaching. Nanofilled resin composite staining can be partially reduced by in-office bleaching agents but not completely removed. Practical ImplicationsTo reduce the increase in surface roughness of composite restorations due to bleaching, polishing should be applied before and after bleaching.

Combined effects of moss colonization and rock fragment coverage on sediment losses, flow hydraulics and surface microtopography of carbonate-derived laterite from karst mountainous lands

Moss and rock coverage play important roles in the soil erosion processes of karst mountainous lands. We conducted simulated rainfall experiments to investigate the combined effects of moss colonization and rock fragment coverage (RC) on the sediment losses, flow hydraulics and surface microtopography of karst carbonate-derived laterite. Soil slopes with moss colonization and different rock fragment coverages (0, 30 % and 60 %) were subjected to simulated rainfall with intensities of 100 mm h−1 in 50 cm × 30 cm × 15 cm flumes. Two sequential soil erosion events, E1 and E2, were induced with two rainstorm events; E2 was induced 24 h after E1. The results showed that the mean runoff rates (MR) of moss-covered slopes with 0 and 30 % RC were significantly lower than those of bare slopes (by 27.78 % and 24.06 %, respectively), and this effect gradually decreased as RC increased. Moss coverage also significantly decreased the mean flow velocity, and RC without moss coverage increased the flow velocities during rainfall. Moss-covered slopes showed significant decreases in mean sediment loss (MSL) (by 64.87 %, 78.89 % and 87.03 % for the 0, 30 % and 60 % RC in the E1 + E2 conditions, respectively) relative to bare slopes, and RC increases also decreased MSL. In addition, moss colonization significantly increased the initial slope roughness in both the horizontal (cl) and vertical (RR) directions. With moss coverage, slope roughness was less affected by slope erosion events due to protective effects. These results provide reference data for researching the mechanisms of moss and rock coverage for controlling and preventing karst slope erosion.

Selective laser melting of oxide dispersion strengthened MA956 alloy and its surface finishing by magnetic field assisted finishing

Selective laser melting (SLM) is a prominent metal additive manufacturing (AM) capable of processing a myriad of engineering materials with high precision and design freedom. However, similar to other AM processes, poor surface finishing has been an omnipresent problem in SLM technology. In this study, magnetic field assisted finishing (MAF) was used to finish SLM fabricated oxide dispersion strengthened (ODS) MA956, an iron‑chromium‑aluminum alloy. The effect of laser processing parameters on part density and surface roughness was first studied. Using a multi-objective optimization technique, the optimal parameters to obtain the highest density and lowest surface roughness were determined. Finally, MAF was applied to the parts built with the obtained optimal SLM parameters, but without significant improvement on the surfaces of as-printed samples. Hence, the surfaces of as-printed samples were post-processed (ground) to yield better initial surface conditions prior to MAF. The effect of initial roughness, iron particles size, and abrasive size on MAF performance was studied. Initial roughness had the most dominant effect followed by abrasive size. The underlying mechanism behind the dependency on initial roughness on final surface quality was analyzed by studying the change on the surface profiles with different starting initial roughness. The initial roughness required for MAF to be effective was determined. Using the optimal processing conditions, MAF was applied to the post-processed samples to attain the final average surface roughness (Ra) as little as 0.36 μm starting from initial average roughness (Ra) of 1.53 μm.

Research on surface morphology and characteristics of top-hat fiber laser polishing aluminum alloy 5052

Aiming at the defects such as cracks in the polishing process of aluminum alloy 5052, the laser polishing of aluminum alloy 5052 was studied, and a new top-hat beam laser polishing method was proposed for aluminum alloy 5052. The energy distribution in the polishing process was well-distributed, which greatly improved the energy utilization efficiency and reduced the surface roughness. Confocal microscopy and SEM were used to obtain the microstructure and phase composition of the microstructures. The results showed that the surface roughness was considerably reduced to lengthen the service life of the aluminum alloy 5052 materials from an initial roughness of Sa = 3.9 μm to Sa = 1.32 μm after using top-hat fiber laser polishing.

Enhancing the Accuracy of Water-Level Forecasting with a New Parameter-Inversion Model for Estimating Bed Roughness in Hydrodynamic Models

The accurate and efficient estimation of bed roughness using limited historical observational data is well-established. This paper presents a new parameter-inversion model for estimating bed roughness in hydrodynamic models that constrains the roughness distribution between river sections. The impact of various factors on the accuracy of inversed roughness was analyzed through a numerical experiment with the number of measurement stations, observed data amount, initial bed roughness, observational noise, and the weight of the regularization term. The results indicate that increasing the number of measurement stations and the amount of observed data significantly improves the robustness of the model, with an optimal parameter setting of 3 stations and 30 observed data. The initial roughness had little impact on the model, and the model showed good noise resistance capacity, with the error significantly reduced by controlling the smoothness level of inversed roughness using a small weight of the regularization term (i.e., 100). An experiment conducted on a real river using the calibrated model parameters shows a forecasted water level RMSE of 0.041 m, 31% less than that from the Federal Emergency Management Agency. The proposed model provides a new approach to estimating bed roughness parameters in hydrodynamic models and can help in improving the accuracy of water-level forecasting.

Study on the shear-slip process and characteristics of fracture in shale

To clarify the shear-slip process and characteristics of fault, we conducted triaxial shear tests driven by displacement on shale samples with prefabricated sawcut and natural fractures, and the acoustic emission (AE) technology was used to monitor the shear-slip process in real-time. According to the test results, the shear-slip process and mechanical characteristics of sawcut and natural fractures were analyzed. The test results indicate that the shear-slip process of fractures can be divided into four stages, improving the confining pressure will cause more serious plastic failure in the shear-slip process, and the increase of roughness will make the phenomenon of “stress drop” more obvious, which is closely related to the earthquake occurrence. Confining pressure and roughness all have implications for the stress thresholds of each stage. With the transition of shear-slip stages, the effects of confining pressure and roughness on the shear-slip of fractures are more drastic. The maximum static friction coefficient μ0 increases with initial roughness increasing and is independent of confining pressure. Due to the strain-strengthening effect of fracture slip, the average value of dynamic friction coefficient μd under simple shear deformation is greater than the maximum static friction coefficient μ0. Based on AE response characteristics, microcracks development, and rupture scale during the shear-slip process were also explored. AE events are mainly distributed along the inclined fracture. The AE response in different shear-slip stages displays pronounced differences, and the AE evolution and macro mechanical characteristics of fractures show significant time-synchronization. The variation of peak frequency can reflect the rupture scale transformation and the influence of confining pressure and roughness. Additionally, the differences in the morphological evolution of sawcut and natural fractures are mainly reflected in the wear pattern, degree and the rock debris attach amount. Finally, we also discussed the micro-deformation mechanism of asperities during the shear-slip process. This work may provide a reference for the research of fault activation and slip in shale reservoirs.

Multi-performance optimization of the diamond burnishing process in terms of energy saving and tribological factors

Surface characteristics can be improved using diamond burnishing. In this work, an ecological indicator (energy efficiency- EF) and tribological factors (the coefficient and friction- COF and specific wear rate- SWR) of a single diamond burnishing process were optimized. The process parameters were the burnishing speed ( V), burnishing depth ( D), feed rate ( f), the diameter of the tip ( DT), and initial average roughness ( IR). An efficient cooling-lubrication device comprising the minimum quantity lubrication and Ranque–Hilsch vortex tubes was utilized to facilitate burnishing trials. The Kriging models of burnishing performances were developed regarding parameters. The CRITIC method, Crow Search Algorithm, and TOPSIS were employed to select weights and optimality. The optimizing outcomes indicated that optimal values of the V, D, f, DT, and IR were 160 m/min, 0.10 mm, 0.05 mm/rev., 7 mm, and 2.00 μm, respectively. The EF was improved by 34.1%, while the COF and SWR were decreased by 33.2% and 8.1%, respectively. The optimal data could be applied to practical diamond burnishing to improve energy efficiency and tribological parameters for burnished external surfaces. The optimizing technique comprising the Kriging models, CRITIC, Crow Search Algorithm, and TOPSIS could be efficiently utilized to solve complex issues for burnishing operations and other machining processes. A developed system could be applied to enhance cooling-lubrication efficiencies for different machining operations, such as turning, milling, and grinding processes.

Describing and Modeling Rough Composites Surfaces by Using Topological Data Analysis and Fractional Brownian Motion.

Many composite manufacturing processes employ the consolidation of pre-impregnated preforms. However, in order to obtain adequate performance of the formed part, intimate contact and molecular diffusion across the different composites' preform layers must be ensured. The latter takes place as soon as the intimate contact occurs and the temperature remains high enough during the molecular reptation characteristic time. The former, in turn, depends on the applied compression force, the temperature and the composite rheology, which, during the processing, induce the flow of asperities, promoting the intimate contact. Thus, the initial roughness and its evolution during the process, become critical factors in the composite consolidation. Processing optimization and control are needed for an adequate model, enabling it to infer the consolidation degree from the material and process features. The parameters associated with the process are easily identifiable and measurable (e.g., temperature, compression force, process time, ⋯). The ones concerning the materials are also accessible; however, describing the surface roughness remains an issue. Usual statistical descriptors are too poor and, moreover, they are too far from the involved physics. The present paper focuses on the use of advanced descriptors out-performing usual statistical descriptors, in particular those based on the use of homology persistence (at the heart of the so-called topological data analysis-TDA), and their connection with fractional Brownian surfaces. The latter constitutes a performance surface generator able to represent the surface evolution all along the consolidation process, as the present paper emphasizes.