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Due to their durability and esthetic appeal, porcelain tiles have become a staple in modern construction and interior design. However, the persistent challenge of mitigating slip hazards, particularly in moist conditions, remains a critical concern for pedestrian safety. This study investigates the slip resistance performance of porcelain tiles, focusing on the influence of varying surface textures. The study clarifies the intricate relationship between surface texture and slip resistance through comprehensive dynamic friction tests involving four distinct porcelain tile samples and three different shoe samples conducted under arid, damp, and lathered conditions. Whereas dry conditions showcase robust traction, moist environments underscore the significance of surface textures in enhancing grip. Moreover, the study introduces an operational scale of surface roughness, delineating optimal texture boundaries for maximal slip resistance. The implications of these findings extend beyond mere material characterization, offering actionable insights for architects, designers, and safety professionals to enhance pedestrian safety in diverse settings. By bridging the gap between material science and real-world safety concerns, this research paves the way for innovative porcelain tile designs that prioritize safety without compromising esthetic appeal. [ABSTRACT FROM AUTHOR]

Surface texture plays a role in enhancing the performance of hydrodynamic journal bearings by reducing friction coefficients and increasing load-carrying capacity. However, its impact on the dynamic performance of the bearings remains largely unexplored. This study aims to fill this gap by investigating the optimized surface texture of twin-grooved two-lobe hydrodynamic journal bearings using genetic algorithms. Through the optimization of surface texture, significant enhancements in the dynamic performance of the bearings, including improvements in fluid film damping, stiffness, and omega threshold speed, are achieved. Utilizing GA optimization, textured bearings demonstrate a remarkable enhancement in dynamic performance, with an impressive increase of 195.55% in omega threshold speed. These findings provide valuable insights for enhancing bearing designs and stability, thereby contributing to advancements in tribological engineering. [ABSTRACT FROM AUTHOR]

Axial piston pumps with compact structures and high efficiency are widely used in construction machinery. The efficiency and lifetime strongly depend on the tribological performance of the pump's valve plate pair. To enhance the tribological performance of the valve plate pair, surface textures, and H-DLC coatings were fabricated to modify the CuAl10Fe5Ni5 surfaces. The influences of elliptic textures of different sizes and textured H-DLC coatings on the surface friction and wear properties of the valve plate surface under oil lubrication were evaluated using a ring-on-disk tribometer. The results reveal that the friction and wear properties of the CuAl10Fe5Ni5 surfaces are significantly enhanced by elliptic textures, and the friction coefficient and wear rate of textured CuAl10Fe5Ni5 with E90 are maximally decreased by 95% and 87%, respectively. Compared with the surface textures and H-DLC coatings, the textured H-DLC coating has the greatest ability to reduce wear and adhesion. The wear rate of the textured H-DLC coating is further reduced by 98%. This improvement can be explained by the synergistic effect of the elliptic textures and H-DLC coatings, which are attributed to the reduced contact area, debris capture, and secondary lubrication of the elliptic textures, and increased surface hardness. [ABSTRACT FROM AUTHOR]

Abstract This work investigates how the surface textures and morphology of pyroxene grains evolve during their source‐to‐sink history. This study applies to detrital clinopyroxenes concentrated in coastal dune sands of the Gulf of Mexico which were sourced in the Trans Mexican Volcanic Belt then transported and deposited in environments subject to limited chemical weathering. The composition and morphology of the pyroxenes was characterised using single‐grain geochemical analysis and surface texture imagery with a novel approach based on the compactness property to assess the shape of minerals. This reveals heterogenous diopside‐augite populations, displaying mineral morphologies dominantly controlled by impact breakage along cleavages, little physical abrasion along their edges and with limited evidence for chemical weathering. Mechanical surface textures dominate over mechanical/chemical and chemical surface textures. These mechanical surface textures are preserved primarily as flat cleavage surfaces and rounded edges inherited from fluvial‐intertidal and aeolian transport, respectively. Mechanically/chemically induced surface textures are preserved as elongated depressions. Chemical surface textures are sparse and mostly represented by mammillated textures that suggest local dissolution under subaqueous conditions. The scarcity of chemical surface textures is attributed to frequent fragmentation of the clinopyroxenes along cleavages and limited chemical weathering during transport of the observed populations. Clinopyroxene grains in the coastal dune sands primarily retain surface characteristics from fluvial transport. Although the breakage of minerals along cleavages can obscure their original morphology under a weathering‐limited erosion regime, this study shows how surface textures and morphology of pyroxene grains is used to determine episodes of transport and deposition close to volcanic environments. The use of the compactness property as a shape descriptor measurement of particles provides an alternative approach to observe how clinopyroxene remains unaltered despite the high energy conditions of the coastal area.

Machining a 5 mm hole in molybdenum disilicide-silicon carbide, an extremely rigid and robust intermetallic compound, is challenging. The effectiveness of Electrical Discharge Machining (EDM) was evaluated using standard metrics such wear ratio, material removal rate, electrode wear rate, average surface roughness, and geometrical tolerances. This research article notably features an in-depth analysis of the melting and evaporation mechanism of metal removal, along with the topography of the machined surface, using an EDS and XRD report, machined electrodes, and WEDM machined brass wire. Surface morphologies have been characterized using scanning electron microscopy (SEM) at the several experimental levels for the machined composite, electrode, and wire. Current of 5 A, pulse on time of 8 µs, pulse off time of 6 µs, spark gap of 0.16 mm, dielectric pressure of 20.5 kg/cm2, metal removal rate of 0.00117 g/min, electrode wear rate of 0.00011 g/min, wear ratio of 10.60%, and surface roughness of 0.441 µm achieved the best results. According to the evaluation and analysis of porosity values, the level 1 trial's hole has a porosity value of 0.966%, the level 3 trial's t hole has a porosity value of 5.655%, and the level 2 trial's hole has a porosity value of 1.424%. The experimental results on the machined surface of the copper electrode show that by selecting the best level of process parameter combination, the machining accuracy with good geometrical tolerances, surface quality are enhanced and number of micro voids, and size of cracks were all minimized. [ABSTRACT FROM AUTHOR]

This work investigates how the surface textures and morphology of pyroxene grains evolve during their source‐to‐sink history. This study applies to detrital clinopyroxenes concentrated in coastal dune sands of the Gulf of Mexico which were sourced in the Trans Mexican Volcanic Belt then transported and deposited in environments subject to limited chemical weathering. The composition and morphology of the pyroxenes was characterised using single‐grain geochemical analysis and surface texture imagery with a novel approach based on the compactness property to assess the shape of minerals. This reveals heterogenous diopside‐augite populations, displaying mineral morphologies dominantly controlled by impact breakage along cleavages, little physical abrasion along their edges and with limited evidence for chemical weathering. Mechanical surface textures dominate over mechanical/chemical and chemical surface textures. These mechanical surface textures are preserved primarily as flat cleavage surfaces and rounded edges inherited from fluvial‐intertidal and aeolian transport, respectively. Mechanically/chemically induced surface textures are preserved as elongated depressions. Chemical surface textures are sparse and mostly represented by mammillated textures that suggest local dissolution under subaqueous conditions. The scarcity of chemical surface textures is attributed to frequent fragmentation of the clinopyroxenes along cleavages and limited chemical weathering during transport of the observed populations. Clinopyroxene grains in the coastal dune sands primarily retain surface characteristics from fluvial transport. Although the breakage of minerals along cleavages can obscure their original morphology under a weathering‐limited erosion regime, this study shows how surface textures and morphology of pyroxene grains is used to determine episodes of transport and deposition close to volcanic environments. The use of the compactness property as a shape descriptor measurement of particles provides an alternative approach to observe how clinopyroxene remains unaltered despite the high energy conditions of the coastal area. [ABSTRACT FROM AUTHOR]

Veneered zirconia ceramics are widely used for dental restorations. However, the relatively poor bonding strength between the ceramic core and veneer porcelain remains a common problem in clinical applications. To address this issue, this study focused on enhancing the core–veneer bond strength of zirconia restorations through the implementation of surface textures using digital light processing (DLP) technology. The light intensity was precisely tuned to optimize mechanical strength and minimize light scattering. Subsequently, hexagonal or square grids were printed on the surface of the zirconia ceramic core. Following veneering procedures, the shear bond strength (SBS) test was conducted using a universal testing machine. Dates were compared using analysis of variance (ANOVA) and the least significant difference (LSD) test. Furthermore, optical microscopy and scanning electron microscopy (SEM) were used to examine the failure modes and observe the cross-sectional structures, respectively. The results indicated that the presence of a 0.09 mm high hexagon grid led to a significant 21% increase in the SBS value. However, grids with heights of 0.2 and 0.3 mm showed less improvement, owing to the formation of large defects at the interface during the fusion process. This study demonstrated the potential of DLP technology in preparing zirconia ceramics with complex structures and high mechanical strength, thereby offering promising solutions for overcoming challenges associated with dental applications. [ABSTRACT FROM AUTHOR]

In the Inertial Confinement Fusion facilities, single-point diamond fly-cutting and micro ball-end milling are the main techniques to fabricate the large-aperture KDP (KH 2 PO 4) optics and repair the surface defects on KDP, respectively. These machining processes inevitably generate various surface textures on the machined optics while the effect of these surface textures on the optical performance of machined optics has not been clarified yet. In this work, the light intensity modulation inside KDP machined by single-point diamond fly-cutting and micro ball-end milling processes was firstly analyzed and the characterizing methods of these machined surface textures were then investigated. It is found that the machining-caused surface textures with higher amplitude and smaller spatial period could result in more severe light intensity modulation inside KDP optic which has been acknowledged as one of the most important factors causing laser-induced damage to KDP. Moreover, the relative directions (i.e., parallel or perpendicular) between these textures on the front and rear surfaces of KDP could have a distinct effect on their light intensity modulation. For characterizing the texture structures, especially, texture direction, power spectrum density (PSD), and fractal dimension were adopted. The PSD analysis results indicate that the dominated textures on single-point diamond fly-cutting surfaces are mainly along the feed direction while the dominated textures on micro ball-end milling surfaces are perpendicular to the feed direction. These textures on micro ball-end milling surfaces have been identified as the residual tool marks whose period equals the step over of the milling process. The fractal dimension can precisely evaluate the machined surface roughness and texture directions. But in comparison, the angular spectrum of PSD has higher characterizing accuracy than the circumferential profile of the fractal dimension approach. [ABSTRACT FROM AUTHOR]

A CuCoBe–diamond composite was used to reinforce a laser textured 410 stainless steel piston ring by hot-pressing. Different hot-pressing parameters were used to optimize the sintering process of the CuCoBe particles (P = 25 and 50 MPa, T = 820 and 980 °C, and t = 15 and 30 min). The results showed an increase in the hardness of the hot-pressed samples (50.5% and 48.5% for P = 25 and 50 MPa, respectively). Three textures with different track widths and distances between them were produced by laser on the compression piston rings' surface. The composite powders were used for the reinforcement of the textures by hot-pressing at the optimized sintering parameters (T = 980 °C, P = 25 and 50 MPa, and t = 15 min). The tribological results revealed that larger texture dimensions led to enhanced tribological performance. [ABSTRACT FROM AUTHOR]

To evaluate various interlaminar bonding reinforcement techniques used for steel bridge decks, the UHPC surface was roughened with shot blasting (SB), transverse grooving (TG) and surface embedded stone (S), epoxy resin (E), epoxy asphalt (EA) and high viscosity high elasticity asphalt (HV) as interlayer bonding materials. In addition, a diagonal shear test was conducted using a self-designed diagonal shear jig. The effects of adhesive layer materials type, surface texture type, and different loading rates on the interlaminar bonding performance of UHPC/SMA combination specimens were investigated. The experimental study showed that the peak shear strength and shear modulus of the combined specimen decreased gradually with the decrease of thermosetting of the adhesive layer materials. The peak shear fracture energy of E was greater than that of HV and EA. The synergistic effect of the contact force generated by the roughing of the UHPC surface, the friction force, and the bonding force provided by the adhesive layer material can significantly improve the interlaminar shear performance of the assemblies. The power-law function of shear strength and shear modulus was proposed. The power-law model of peak shear strength and loading rate was verified. The shear strength and predicted shear strength satisfy the positive proportional functions with scale factors of 0.985, 1.015, 0.961, and 1.028, respectively. [ABSTRACT FROM AUTHOR]

Haptic rendering of surface textures enhances user immersion of human–computer interaction. However, strict input conditions and measurement methods limit the diversity of rendering algorithms. In this regard, we propose a neural network-based approach for vibrotactile haptic rendering of surface textures under unconstrained acquisition conditions. The method first encodes the interactions based on human perception characteristics, and then utilizes an autoregressive-based model to learn a non-linear mapping between the encoded data and haptic features. The interactions consist of normal forces and sliding velocities, while the haptic features are time–frequency amplitude spectrograms by short-time Fourier transform of the accelerations corresponding to the interactions. Finally, a generative adversarial network is employed to convert the generated time–frequency amplitude spectrograms into the accelerations. The effectiveness of the proposed approach is confirmed through numerical calculations and subjective experiences. This approach enables the rendering of a wide range of vibrotactile data for surface textures under unconstrained acquisition conditions, achieving a high level of haptic realism. • A neural network-based method for vibrotactile haptic rendering of surface textures under unconstrained acquisition conditions is proposed. • A coding method is designed based on human physiological physics characteristics. • Required no strict data segmentation methods. • Tactile perception of vibration with high realism is achieved. [ABSTRACT FROM AUTHOR]

Surface texturing can improve the performance of journal bearing system. The present study theoretically investigates the impact of surface textures on the dynamic stability and performance parameters of two-lobe journal bearing system. Galerkin's finite element method is used to solve the Reynolds equation governing the flow of lubricant in the gap between the bearing and the journal. Reynolds boundary conditions are applied in the simulation study of plain, full-textured, partially textured-I and partially textured-II configurations of two-lobe journal bearing. The dynamic stability and performance parameters of textured two-lobe journal bearings are computed with the variation of eccentricity ratio and dimple depth and compared with circular bearing results. The results indicate that the existence of surface textures in the pressure build-up zone ranging from 126°–286° and at unity dimple aspect ratio can significantly improve the dynamic stability and performance parameters of two-lobe bearing system. [ABSTRACT FROM AUTHOR]

[Display omitted] • EHDA and laser micro-cladding are used to fabricate micro-textures on tool surface. • The cladding layer region has higher hardness than substrate. • The textured samples have lower friction coefficient than polished substrate. • The cutting performance of the textured cutting tool is improved slightly. The application of mechanization in different environments has put forward strict requirements for mechanical components, which also means higher requirements for cutting tools. It is precisely these requirements that drive the development of cutting tool preparation methods towards novelty and innovation. To effectively enhance the performance of dry cutting tools, laser micro-cladding technology has been innovatively adopted to achieve additive manufacturing of new textured cutting tools. The mechanical properties, tribological properties, and cutting performance of the newly textured tools were evaluated. The results indicate that the EHDA process can achieve uniformity and thickness controllability of the preset powder layer. In friction experiments, the friction coefficient of textured surfaces can be reduced by up to 44.3% compared to polished surfaces. In the cutting experiment, the cutting force of LCT tools has decreased by up to 26.7%, and the cutting temperature has decreased by a maximum of 32.5%. The research mechanism indicates that at lower cutting speeds, WS 2 forms a lubricating film at the tool-chip contact interface, reducing shear strength and achieving a reduction in cutting force and cutting temperature. And the micro-textures are the main way for the LCT tool to reduce cutting force and cutting temperature at higher cutting speeds. [ABSTRACT FROM AUTHOR]

In self-lubricating sliding contact facilitated with polytetrafluoroethylene (PTFE) composites, the anisotropy in tribological performance was often attributed to the oriented structures of the polymer. However, in this research, it is found that the non-homogeneity introduced by the hard fibres or stiffeners may be the main contributor to the anisotropic tribological performance of the polymeric composites. The interaction between the non-uniformly arranged hard fibres/stiffeners and the metallic counterface was found to be the leading phenomenon of this tribological behaviour. Moreover, the effects from a surface texturing scheme was found capable of establishing intervention to this interaction and reducing the anisotropy. The mechanism of the texturing effects was found related with back-transfer of PTFE and trapping of wear debris. [ABSTRACT FROM AUTHOR]

Studies on the effect of wall textures and crystallographic grain orientations on graphene coatings and water droplets wettability are conducted. To date, there is almost no data on the effect of surface textures and high‐temperature annealing on the wettability of the graphene‐coated copper. It is generally accepted that the water contact angle on the graphene‐coated copper with one graphene layer is ≈85°–86°. However, changing the annealing duration, and using different surface textures, it is possible to change the graphene wettability over a wide range of static droplet contact angles from 81° to 96°, which allows providing both hydrophilic and hydrophobic properties. With the growth of annealing duration, the average grain size increases from 0.1–1 to 10 mm and more. By changing the annealing duration and the surface roughness, it is possible to realize the grains orientation (001) and (111), as well as the simultaneous presence of different grains orientations. Molecular dynamic modeling of the influence of orientation and grain size on the wettability of the graphene coating is performed. The calculation results correspond to the experimental data on contact angles. The key factors affecting the wettability of graphene are presented and analyzed. [ABSTRACT FROM AUTHOR]

To enhance the tribological properties of Si 3 N 4 based ceramics, surface textures of dimples combined with DLC coatings are fabricated on Si 3 N 4 /TiC ceramic surface by nanosecond laser and plasma enhanced chemical vapor deposition (PECVD). The dry friction and wear performances are evaluated by unidirectional sliding friction tests using a rotary ball-on-disk tribometer. Results reveal that the friction and wear properties of Si 3 N 4 /TiC ceramics are significantly enhanced by DLC coatings or dimpled textures, and the DLC coatings combined with dimpled textures show the best efficiency in reducing friction, adhesion and wear. This improvement can be explained by the synergistic effect of DLC coatings and surface textures, and the synergistic mechanisms are attributed to the formation of lubrication film and secondary lubrication, debris capture of dimpled textures, increased surface hardness and mechanical interlocking effect, and reduced contact area. [ABSTRACT FROM AUTHOR]

The triboelectric nanogenerator (TENG) is a new mechanical energy harvesting technology in which the typical viscoelastic material polydimethylsiloxane (PDMS) is widely used. Micro-/nano-textures are often fabricated on the PDMS surface to enhance the electrical performance of TENG. As the contact region decreases to micro/nano scale, the adhesive forces become dominant. However, there is still a lack of contact mechanics model considering both material viscoelasticity and the adhesive forces to guide the surface texture design. In this paper, the explicit data-fitting formulas based on the fractional derivative Zener model are firstly derived to identify the viscoelastic constitutive parameters, which can not only avoid the influence of the initial contact point, but also ensure the accurate conversion between the creep compliance and the relaxation modulus function. Then a viscoelastic-adhesive contact model based on the fitted constitutive parameters is established, and the numerical algorithms such as bi-conjugate stabilized (Bi-CGSTAB) method and fast Fourier transform (FFT) technique are employed to analyze the effects of material viscoelasticity and texture sizes on the contact and electrical performance. It is shown that, compared with results from the elastic-adhesive contact model, the contact area ratio based on the viscoelastic-adhesive contact model is significantly larger, which is much closer to the experimental results. Among the selected sizes of pyramid texture, the higher electrical performance can be obtained from the textures with a smaller pitch and a larger width under the heavier applied load. This study can provide a theoretical reference for the design of viscoelastic surface texture of TENG. [ABSTRACT FROM AUTHOR]

As a branch of laser cladding technology, laser micro-cladding shows unique local selective processing characteristics. Based on laser micro-cladding technology, this article proposes a new method for the in-situ formation of textured surfaces using laser micro-cladding technology. A Ni60/WC/WS 2 composite coating was prepared on the cemented carbide substrate using laser micro-cladding technology, and a micro-groove structure was formed in situ. The microstructure, mechanical properties and tribological performance of laser micro-cladding Ni60/WC/WS 2 composite coating were studied. The results show that laser micro-cladding technology can effectively prepare periodic controllable micro-textures with micron-sized dimensions, and the thickness of the laser micro-cladding composite coating can reach ∼300 μm. The hardness of composite coating can reach ∼28.48 GPa. The composite coating and micro-texture have a synergistic effect and can effectively improve the tribological properties of the substrate. The LCT sample has the lowest friction coefficient, with an average friction coefficient of ∼0.38. Due to the high hardness of the composite coating, it shows better wear resistance, but the micro-textured edge will cut the steel ball during the friction process, causing the steel ball wear rate of the LCT sample to reach ∼45.86 × 10−5 mm3/Nm. The exploration of laser micro-cladding in-situ forming textured surfaces provides experimental support for the application of cutting tools, brake discs and other mechanical components. • Micro-textures were prepared on the substrate by laser micro-cladding technology. • Textures and coating have synergistic effect to reduce the friction coefficient. • The coating has high hardness and good wear resistance. • Laser micro-cladding in-situ formed textured surface provide experimental support. [ABSTRACT FROM AUTHOR]

Hydrodynamic lubrication of rectangular micro-textures on sliding contact surfaces is investigated using numerical calculation methods. The theoretical models for the slider surface are developed and the film pressure is used to evaluate the hydrodynamic lubrication based on the Reynolds equation. Meanwhile, the geometry and distribution of the rectangular dimples are optimized for maximizing the average film pressure. Results show that the film pressure is dependent on the geometry and distribution of the rectangular micro-dimples. The optimal geometry of the single rectangular dimple is obtained, and the spacing has an important influence on the film pressure. The distribution types of rectangular dimples affect the hydrodynamic lubrication significantly and the interlaced array of the rectangular micro-dimples is beneficial to enhancing the hydrodynamic lubrication. Meanwhile, the rectangular dimples with 72° interlaced angle exhibits the best effectivity. [ABSTRACT FROM AUTHOR]

In order to obtain rotating machinery with improved energy efficiency, the approach of surface texturing journal bearings has been adopted to reduce the viscous dissipation in the lubricant. A possible reduction in shear viscous forces in the bearings of rotating machines could reduce the amount of heat released along its operation, resulting in a lower operating temperature that tends to improve journal bearings performance and the machine's energetic efficiency. Thus, this work aims to investigate the texturing of journal bearings under dynamic loading conditions, considering the application in rotating systems. For this, computational simulations are performed through a rotating system model constructed by means of the finite element method in which the hydrodynamic journal bearings that support the rotor are modeled by Reynolds' equation using the finite volume method and the full multigrid technique. The numerical results show that textured journal bearings can be applied to rotating machines, providing reductions in shear viscous forces. However, the magnitude of this reduction should be carefully evaluated, as the Reynolds cavitation model was applied to ensure a lower computational spent time and thus enable the simulations involved in this study. The novelty of this study is related to determining the appropriate distributions and geometric parameters of the textures for the journal bearing under dynamic load condition considering its equivalent static load condition what tends to drastically reduce computational time to perform this procedure, representing an important alternative for industrial application. [ABSTRACT FROM AUTHOR]

Surface finish has a significant impact on the properties (e.g., fatigue strength and corrosion resistance) of manufactured products; consequently, industries seek to quantitatively evaluate the surface finish of their products. The surface finish of test specimens, made of the aluminum alloy A L 7075 − T 6 , has been measured with a confocal microscope, where the ensemble of collected experimental data has been analyzed by the following four methods of surface texture quantification: (i) arithmetical mean height S a ; (ii) root mean square height S q ; (iii) maximum height S z ; and (iv) ten-points height S 10 z. This paper addresses automated prediction of surface quality by an artificial neural network (ANN) that has been used to classify the analyzed values of surface textures based on the concept of pattern recognition. The best surface textures are determined by relying on the performance of the ANN model, which depends on the accuracy, precision, recall, and F1-score of the test data. The results show that, for small variations in surface finishing, the test method S 10 z most accurately predicts quality of surface textures, which is followed by the test method S a. • Investigating the status of the surface for controlling the quality of manufacturing processes such that poor surface quality can be reliably detected. • For managing the production process, recall and precision of the AI model could deliver more accurate evaluation. • Other surface texture parameters,(e.g. Sz and S10z) may be capable of delivering a better insight into the surface of a component. [ABSTRACT FROM AUTHOR]

Passive heat exchangers (HXs) form an inseparable part of the manufacturing industry as they provide high-efficiency cooling at minimal overhead costs. Along with the aspects of high thermal cooling, it is essential to monitor pressure loss while using plate-fin HXs because pressure loss can introduce additional power costs to a system. In this paper, an experimental study was conducted to look at the effects of dimples on the pressure drop characteristics of single plate-fin heat exchangers. To enable this, different configurations of National Advisory Committee for Aeronautics (NACA) fins with smooth surfaces and 2 mm-diameter dimples, 4 mm-diameter dimples and 6 mm-diameter dimples were designed and 3D printed using fused deposition modelling (FDM) of ABS plastic. The depth to diameter ratio for these dimples was kept constant at 0.3 with varied diameters and depths. These were then tested using a subsonic wind tunnel comprised of inlet and outlet pressure taps as well as a hot wire velocimeter. Measurements were taken for pressure differences as well as average velocity. These were then used to calculate friction factor values and to compare the smooth fin to the dimpled fins in relation to their relative pressure drop performance. It was observed that for lower velocities the 4 mm dimples provided minimum pressure drop, with a difference of 58% when compared to smooth fins. At higher velocities, 6 mm dimples increased the pressure drop by approximately 34% when compared to smooth fins. It can also be concluded from the observed data in this study that shallower dimples produce lower pressure drops compared to deeper dimples when the depth to diameter ratio is kept constant. Accordingly, deeper dimples are more effective in providing drag reduction at lower velocities, whereas shallower dimples are more effective for drag reduction at higher velocities.

Micro-dimples are the basic surface textures that have played an important role in reducing or increasing friction, anti-wear, decreasing vibration, anti-adhesion, and creeping. Electrochemical micromachining (EMM) is a popular method for preparing micro-dimples. The method of sandwich-like electrochemical micromachining (SLEMM) can be used to enhance machining accuracy of micro-dimples, due to the electrolytic products accumulated on the workpiece surface in the enclosed unit of SLEMM. Therefore, this paper focuses on exploring the influence of bubbles accumulated on the workpiece theoretically and experimentally. The theoretical analysis indicated that 0.2 s machining time is required, and the theoretical maximum depth of micro-dimple is 7.3 μm when the electrochemical dissolution reaction is terminated. The CCD camera was employed to observe the process of SLEMM, and the observations indicated that the changes of gas bubbles are very complex and the electrolytic products accumulated on the workpiece surface have a significant influence on the preparing of micro-dimples. In addition, the experimental results indicate that the dimensions of micro-dimple vary little and the maximum depth of 4 μm for micro-dimples could be prepared with the increase of applied voltage, machining time, and thickness of mask, because of the electrolytic products accumulated on the workpiece during SLEMM. [ABSTRACT FROM AUTHOR]

Interfacial issues have always been the top priority of tribology which directly affect tribological performance of friction materials and output characteristics of Ultrasonic Motors (USMs). Therefore, from the perspective of bionics, a series of surface textures with different parameters were designed to regulate friction interface. The tribological properties of textured friction materials were systematically analyzed. The results found that tribological performance was affected by positive and negative aspects. Consequently, there is an optimal parameter in the case of the best tribological behavior. The optimal parameter was obtained by virtue of orthogonal experimental design and matrix analysis based on mathematical statistics. Additionally, the energy conversion efficiency of USMs with textured friction materials compared to untextured samples increased by 29%. • The surface textures were used to increase the energy conversion efficiency of USMs. • The tribological properties of textured friction materials were systematically analyzed. • The reason for the improvement of the output characteristics of the USMs was revealed. • PTFE composites with surface textured show a high potential for using as tribo-materials for USMs. [ABSTRACT FROM AUTHOR]

Tools in cold forging processes experience high loads. In order to reduce the process loads, solid and liquid lubricants are used. The use of lubricants is disadvantageous due to ecological, economical, and legislative reasons. Novel approaches in cold forging aim at the use of ecologically benign lubricants or avoiding the usage of lubricants completely. This paper focuses on the substitution of lubricants in cold forging by surface textures on workpieces and self-lubricating coatings on tools. The potential of surface textures on workpieces and self-lubricating tool coatings to reduce friction and wear in dry forging was demonstrated in preliminary work using analogy experiments. After analogy tests under dry tribological boundary conditions have shown positive results in preliminary work, dry full forward extrusion tests were performed in this work. Firstly, the focus of the investigations was on feasibility. Secondly, the potentially best combination with regard to friction and wear reduction was selected. Thirdly, in addition to force profiles, the surface of cold forging dies was studied by means of SEM. At the same time, the processes were supported by a validated numerical FE process simulations with the simulation software Forge NxT 2.1. The dry full forward extrusion experiments were successful, because the specimens were extruded until the final point and could be ejected without failure. It was observed that the highest wear of the dies occurred not in the region with the highest tool load but in the region with relatively low loads. Furthermore, it was shown that no wear model suitable for cold forging exists so far. • The research article deals with the study of dry full forward extrusion. • In particular, investigations into the most influential signs of wear are new. • Imaging of wear was investigated using finite element method firstly in cold forging. [ABSTRACT FROM AUTHOR]

This article proposes a novel approach to generate patterned indentations for different additive manufacturing methodologies. Surface textures have many practical applications in various fields, but require special manufacturing considerations. In addition to conventional manufacturing processes, additive processes have also been utilized in the last decade to obtain textured surfaces. The current design and fabrication pipeline of additive manufacturing operations have many disadvantages in that respect. For instance, the size of the design (CAD) files grows considerably when there are detailed indentations on the surfaces of the artifacts. The presented method, which employs morphological operations on a sequence of binary images representing the cross-sections of the printed artefact, overcomes such problems while fabricating the textured objects. Furthermore, the presented technique could be conveniently implemented using the existing hardware resources of almost any three-dimensional printer. [ABSTRACT FROM AUTHOR]

The performance of surface textures with dimensional uncertainty due to the manufacturing process is investigated with statistical models. The uncertainty parameters are geometrical dimensions (i.e., dimple diameter, area ratio, and dimple depth) and the performance parameters include the friction force, the load-carrying capacity, and the coefficient of friction. The results show that logarithmic models provide an excellent fit to the data and can explain more than 99.98% of the variance in data. The most critical geometric parameter for the coefficient of friction and the load-carrying capacity is found to be the dimple diameter, whereas the most critical geometric parameter for the friction force is the area ratio. Manufacturing errors that follow normal distribution with three-sigma quality are found to be insignificant. Under the conditions simulated, it is determined that a dimple diameter of 1883 μm and a dimple depth of 5.5~6.5 μm yield optimal performance when operating in the hydrodynamic lubrication regime. The area ratio is the key parameter and must be determined based on the requirements of the load-carrying capacity and the coefficient of friction.

This paper optimizes the coverage of circular micro-textures on bearing sliders aiming at improving their tribological performance. Grid-like array of textures are arranged to present or absent, which are respectively marked as 1 and 0. Genetic Algorithm is used to evolve the coverages of textures. The algorithm allows the derivation of preferable area for texture coverage in shape of pyramid at the inlet of slider. Evaluation of influences of convergence ratio and width demonstrates that sliders with small convergence ratio and width tend to result in significant tribological improvement effect. Subsequent experimental tests confirmed the achievement of low friction coefficient of the so optimized texture coverage. [ABSTRACT FROM AUTHOR]

Research shows that design factors of packaging and food containers can have a strong impact on taste experience and product evaluation. However, so far research has mainly focused on how visual appearances steer sensory impressions including smell and taste. Taking into account new (technological) developments in packaging design, this research investigates the impact of 3D-printed surfaces on taste evaluation of two ice cream variants. In addition, the interplay between surface textures and matching or non-matching shapes presented on a poster in the consumption environment (i.e., an ice-cream salon) was studied. To this end, 3D-printed cups with either a sharp or smooth surface were manufactured and used in a taste session conducted at an ice-cream salon, where either a poster with sharp or smooth shapes was hanging down the wall. Results testify to the potential of influencing taste evaluations by means of surface textures, with a smooth surface enhancing sweetness evaluation, and a sharp surface enhancing intensity evaluations. Furthermore, findings might imply that mismatches between surface textures and poster design may enhance product and taste liking. [ABSTRACT FROM AUTHOR]

The present work aims to introduce the findings of the investigations of the surface textures of the quartz sand grains and their contribution to the history of sedimentation and diagenesis processes of the studied northern, middle and southern khors sediments in Lake Nasser. The surface textures observed in the quartz grains of the studied sediments emphasize both mechanical (i.e., upturned plates, meandering ridges, mechanical V-shaped pits, conchoidal fractures and oriented cleavage like plates) and chemical (i.e., silica precipitation and dissolution) features. The precipitation and dissolution phenomena are represented by silica globules, silica overgrowths, dissolved upturned plates, and diatoms plastered on sand grains. Such features imply a history of sedimentation of the khors sediments in Lake Nasser including deposition by aeolian processes, then fluvial sedimentation. The effect of consequent diagenetic processes in the khors sediments is represented by silica precipitation and dissolution features. The quartz surface texture reflects implications of the original aeolian environment of some grains in spite of the diagenesis effect.

Materials decorated by the hierarchical micro-nanostructures similar to lotus leaf surface topographies are firmly considered to possess the substantial anti-icing functions, showing icing-delay and low ice adhesion. Here, the aim of this work is to verify the anti-icing capacity in the actual icing environment containing supercooled airflow. This study, therefore, develops both routes to fabricate the hierarchical micro-nanostructure and single nanostructure superhydrophobic surfaces, and first evaluates their anti-icing capacity based on the routine measuring strategies in laboratory. Also, the potential application environment is modeled and used to verify their anti-icing performance for further guiding rational design of surface structures of anti-icing materials. Due to the double-scale effect, the hierarchical micro-nanostructure can induce more air pockets to produce the higher hydrophobicity and anti-icing capacity based on the big reference droplets (diameter > 2 mm) and even static water. However, the verified results in the potential application environment demonstrate that the hierarchical micro-nanostructure exhibits the inferior anti-icing performance, comparing with the single nanostructure. The icing area on the single nanostructure surface is almost half of that on the hierarchical micro-nanostructure surface, also causing a reduction of ≈26 g in icing mass. [ABSTRACT FROM AUTHOR]

Haptic tactile acuity is an important element for object recognition and manipulation. However, ascribing tactile acuity unto artificial systems is extremely challenging, as it requires active touch exploration involving multidirectional manipulation and sensing. This work reports a skin‐inspired liquid‐based microfluidic tactile sensor capable of haptic perception. The tactile sensor comprises a uniquely designed elastomeric structure with a microfluidic protrusion. Multidirectional forces on the protrusion result in unique fluid displacement that can be measured electrically. This unique architecture is sensitive enough to discriminate surface changes below 0.5 mm. Our sensor is thin, flexible, and robust, allowing adhesion to skin to directly discriminate surface features, contour changes, and object stiffness. We further show a proof of concept of our wearable tactile sensor for Braille reading, enabling the identification of letters by scanning across standard Braille codes. This technology has potential in enabling haptic perception for users affected by sensory neuropathy or for implementation in medical, social, and assistive robotics. [ABSTRACT FROM AUTHOR]

Despite good approval for excellent friction regulation, surface texturing seems to be a penalty area for gears mostly because of the traditional cognition of surface (micro-)pitting and structural similarity. Surface micro-textures were applied to the pinion flank to regulate the time-varying meshing stiffness and enhance the meshing characteristics. Results showed the stress regulation and smoothing capability of micro-textures in meshing process, the time-varying meshing stiffness increases by 4.75% and the frictional stability increased by 52%. Experiment results approve that the flank micro-textures can control friction and reduce torque by 26.2%. This study is significant for the systemic design of the dynamic performance and frictional meshing, especially for the gear engagement reliability in space without film lubrication. [Display omitted] • Surface pitting-like micro-textures were preset on flank surfaces of spur gears. • The symmetrical and continuous micro-textures near the pitch line were compared. • The micro-textures are capable to improve the meshing stiffness of gears. • Stress on flanks is rearranged for homogenize distribution after micro-texturing. • Micro-textures regulate the dynamic friction and increase friction stability. [ABSTRACT FROM AUTHOR]