Texture Design Research Articles

Design and Optimization of the Surface Texture at the Hydrostatic Bearing and the Spindle for High Precision Machining

Hydrostatic bearing spindles are widely applied in high precision grinding and turning machines due to their good dynamic stability and rotational accuracy. However, under the condition of high-speed rotations, the heat generated by the friction of the oil film will cause the shear thinning effect. It not only reduces the rotation accuracy of the spindle but also reduces the service life of the spindle. The surface texture structure and configuration between the planes play the role of homogenizing oil film temperature and preventing the bearing surface wear caused by excessive concentration of temperature, which can change the relative motion from the inside of the oil film and thus improve the performance of the hydrostatic spindle more effectively. In this paper, the influence of the surface texture shape and height on the thrust bearing performance of the hydrostatic spindle is systematically investigated by comparative analysis. The CFD simulations are developed to analyze the computational results based on the theory of viscosity-temperature characteristics. The results show that when the height of the surface structure is 1 ~ 2 times the oil film thickness, the spindle bearing performance is the best. The average temperature in the bearing region is the lowest and the accuracy of the simulations was verified by experimental results.

Investigation on micro-textured tappets from design and production to the application properties

In industrial sectors like medical and automotive engineering, the demand for metal components with a high function integration brings conventional production technologies to their limits. This motivates research on innovative processes, which can meet the present requirements on fabricated parts and consequently also the demands on the applied manufacturing process. Part-sided, a high strength, narrow dimensional tolerances and a large functionality is often desired. In addition, an economical component production calls for processes with high material utilization as well as the achievement of short cycle times. The process class of sheet-bulk metal forming, characterized by the application of bulk forming operations on sheet metal, offers the potential to meet these requirements. Currently, sheet-bulk metal forming is mainly used for the fabrication of components with functional elements of macroscopic size. However, microscopic elements and micro-textured surfaces are of high interest for applications in prosthetics and automotive engineering. The objective of this study is therefore to develop an application-oriented method for the design, production and testing of 16MnCr5 metal components, manufactured by a combined process of sheet-bulk metal forming, creating a defined microstructure on the surface. Since the selection of a suitable texture layout and geometry is crucial for tribological optimization, these are designed for their application using numerical elastohydrodynamic lubricant simulations. The contact conditions occurring in the application are modelled as realistically as possible so that texture designs suitable for production can subsequently be compared in test bench trials. It is shown that the tappets produced by forming technology can be efficiently investigated with the test rig presented.

THE TEXTURE OF SONATA-REMINISCENZA (ОР. 38, NO.1) BY NIKOLAY MEDTNER THROUGH THE PRISM OF INTERPRETATIVE TASKS

The article analyzes the Sonata-reminiscenza of Nikolai Medtner from the point of view of the types of piano texture used in it. It is about such distinctive qualities of the musical texture of this work as graphicity, a combination of homophonic-harmonic and polyphonic structure, the relationship between the position in the form and the type of textural design. Starting from the thesis about the priority of the content of musical thematism, the author concludes that only a close analysis of the compositional and dramatic features of the Sonata-reminiscenza of N. Medtner for the performer can become the key to creating an adequate performing concept of the composition and to comprehending its textural features.

Effect of volcano-like textured tools on machining of Ti-6Al-4V alloy: a numerical and experimental analysis

Higher temperature and lower thermal conductivity between the tool-chip contact face easily result in adhesion and wear on the tool surface which negatively affects the tool life and the machining quality of the workpiece in the machining Ti-6Al-4V alloy process. To address these problems, the investigation, combining the simulation and experiment, introduced the volcano-like textures of different diameters with excellent anti-adhesion performance on the tool rake face. Deform-3D software with updated Lagrangian formulation was used for numerical simulation, and the thermo-mechanical analysis was performed using the Johnson-Cook material model to predict the cutting forces, cutting temperature and tool wear. In machining experiments, volcano-like textures (VT) with different diameters were fabricated by fiber laser on the rake face of cemented carbide tools close to the main cutting edge. Experiments in machining Ti-6Al-4V alloy were carried out with the textured tools and non-textured tool under rough machining, semi-finishing and finishing conditions. Then, cutting force, cutting temperature and tool wear were investigated. The results showed that textured tools generally perform better than non-textured tool. The cutting force of VT1 was reduced by 31.2% and 50%, respectively, compared with the non-textured tool under semi-finishing and finishing conditions. With the refinement of machining, the cutting performance of the textured tools is improved, and the service life of the tool is extended. Therefore, the investigation can provide a basis for the surface texture design and optimization of the carbide tool.

Influence of Hatch Strategy on Crystallographic Texture Evolution, Mechanical Anisotropy of Laser Beam Powder Bed Fused S316L Steel

The correlations between process conditions, microstructure, and mechanical properties of additively manufactured components are not fully understood yet. In this contribution, three different hatch strategies are used to fabricate rod‐like samples from S316L stainless steel, which are further investigated using synchrotron diffraction, optical microscopy, and tensile tests. The results indicate the presence of ⟨110⟩ biaxial and fiber textures, whose sharpness depends on the applied hatch strategy. Mechanical tests reveal a strong correlation of the samples’ response to the observed anisotropy in the plane perpendicular to the build direction. Even though the average yield and ultimate tensile strengths of around 475 and 500 MPa, respectively, do not differ significantly, the stress–strain behavior can be correlated with the observed in‐plane anisotropy. Particularly, twinning‐induced plasticity, a distinct increase of the work hardening rate at larger strains and elliptical necking are observed in some samples with biaxial (Goss) texture. These findings indicate that texture design by means of applying dedicated hatch strategies can be used to effectively tune the multiaxial deformation behavior of components produced by laser powder bed fusion.

Temperature Distribution Measurement and Internal Flow Visualization in the Lubrication Film of Non-contacting Mechanical Seals

The surface textures of non-contacting mechanical seals form a few micrometers thick lubrication film that aids in achieving high performance of the seal. Improved texture design can control internal fluid flow, improving the sealing performance and lubrication characteristics. However, film thickness is sensitive to thermal deformation, making seals vulnerable to heat. Excessive temperature increases and deviations in temperature distribution can cause performance degradation or damage to seals. Previous studies have suggested that heat transfer impacting these thermal issues may be influenced by the internal flow, however, experimental studies examining flow fields have not been conducted yet. This study presents the design of experimental equipment, measurement of temperature distributions and observation of flow fields in lubrication films with three different textures—non-textured, Rayleigh step, and spiral groove. Furthermore, the results were compared with those of numerical analysis. Temperature was found to be higher at the downstream end of the flow. In particular, the Rayleigh step seal exhibited a nonuniform temperature distribution that alternated between low and high-temperature areas. This was caused by cooling related to radial grooves that had a pumping effect. In contrast, a uniform temperature distribution was confirmed in the case of the spiral groove seal, which was formed by mixing outer and inner side fluids. The results indicate that the temperature distribution in lubrication films can be controlled via flow field by the surface texture shape or depth to protect against thermal degradation and to achieve high reliability of non-contacting mechanical seals.Graphical

On the microstructure and texture evolution in 17-4 PH stainless steel during laser powder bed fusion: Towards textural design

Additive Manufacturing (AM) of metals allows the production of parts with complex designs, offering advanced properties if the evolution of the texture can be controlled. 17-4 precipitation hardening (PH) stainless steel is a high strength, high corrosion resistance alloy used in a range of industries suitable for AM, such as aerospace and marine. Despite 17-4 PH being one of the most common steels for AM, there are still gaps in the understanding of its AM processing–structure relationships. These include the nature of the matrix phase, as well as the development of texture through AM builds under different processing conditions. We have investigated how changing the laser power and scanning strategy affects the microstructure of 17-4 PH during laser powder bed fusion. It is revealed that the matrix phase is δ-ferrite with a limited austenite presence, mainly in regions of the microstructure immediately below melt pools. Austenite fraction is independent of the printing pattern and laser power. However, reducing the time between adjacent laser passes during printing results in an increase in the austenite volume fraction. Another effect of the higher laser power, as well as additional remelting within the printing strategy, is an increase in the average grain size by epitaxial ferrite grain growth across multiple build layers and the development of a mosaic type microstructure. Changes to the scanning strategy have significant impacts on the textures observed along the build direction, while 〈100〉 texture along the scanning direction is observed consistently. Mechanisms for texture formation and the mosaic structure are proposed that presents a pathway to the design of texture via AM process control.

Space of basis functions to retrieve road surface reflection tables from luminance maps

Road surface reflection tables ( r-tables) relate scene illuminance to luminance seen by a car driver. They are important for many road lighting tasks accounting for road optical properties, such as new illumination design, new pavement texture or lighting design software, to reduce energy consumption without losses on safety and visibility. This paper aims first at finding a space of basis functions to describe r-tables. From a database of 34 r-tables covering a large variety of pavements, a principal component analysis allows to construct a 33-dimensional space, basis for r-table representations. From that statistical model, a method is exposed to retrieve r-table from a luminance map. The estimated r-table is then used to calculate a reconstructed luminance map. Road lighting quality criteria are also derived and they demonstrate the relevancy of the estimated r-table. Finally the model is tested with noisy input data and it remains stable and reliable, making it applicable with experimental luminance maps.

Features of food design on a 3D printer. A review

3D printing technology attracts considerable attention due to its versatility and possibility of using in different industries such as the aerospace industry, electronics, architecture, medicine and food industry. In the food industry, this innovative technology is called food design. 3D printing is a technology of additive manufacturing, which can help the food industry in the development of new and more complex food products and potentially help manufacture products adapted to specific needs. As a technology that create foods layer by layer, 3D printing can present a new methodology for creating realistic food textures by precise placement of structuring elements in foods, food printing from several materials and design of complex internal structures. In addition to appearance and taste, food consistency is an important factor of acceptability for consumers. The elderly and people with dysphagia not infrequently suffer from undernutrition due to visual or textual unattractiveness of foods. The aim of this review is to study the available literature on 3D printing and assess recent developments in food design technologies. This review considers available studies on 3D food printing and recent developments in food texture design. Advantages and limitations of 3D printing in the food industry, possibilities of printing based on materials and consistency based on models as well as future trends in 3D printing including technologies of food preparation by printing on food printers are discussed. In addition, key problems that prevent mass introduction of 3D printing are examined in detail.

Reconstruction of Traditional Village Spatial Texture Based on Parametric Analysis

Chinese traditional villages, as the space carriers of Chinese excellent traditional culture, are a nonrenewable cultural heritage with rich value connotations. The primary consideration for the protection of the authenticity of traditional villages as a historical and cultural heritage is the continuation of spatial authenticity. The inheritance and shaping of traditional characteristics requires the study of the laws of traditional villages’ spatial form. Spatial texture is an important landscape resource for traditional villages, and it is also a space carrier to display and carry the historical and cultural characteristics of the village. However, the current practice of village planning and construction has destroyed this original spatial texture, resulting in a rupture of the inheritance of traditional characteristics of village space. The fundamental reason lies in the lack of emphasis on the subjectivity and regularity of village space and the lack of quantitative analysis and planning application of the inherent laws of spatial texture. Based on the integration of inheritance and transformation, this research proposes to use the advantages of digitization, visualization, and dynamics in parametric technology to quantitatively analyze the internal laws of the village spatial texture and assist the planning and design of the village spatial texture, in order to effectively promote the benign inheritance and optimization of the traditional characteristics of the village spatial texture which makes the planned spatial texture both traditional and modern. The research results show that (1) the parametric-based planning technology can better analyze the existing laws of the village spatial texture in a comprehensive, quantitative, and precise manner. (2) The parametric technology has a relatively high value in the planning and design of the village spatial texture. Due to strong applicability, it can invert the spatial form of the village and optimize the planning scheme by adjusting parameters and rules. (3) Although the parametric planning and design party has certain artificial intelligence, it cannot completely replace the human brain. The planning scheme generated by the method cannot be directly applied but can be used to assist the design scheme. It needs to be adjusted and corrected via the subjective initiative of people and wider participation.

Engineering Emulsion Gels as Functional Colloids Emphasizing Food Applications: A Review.

Gels are functional materials with well-defined structures (three-dimensional networks) assembled from the dispersed colloids, and capable of containing a large amount of water, oil, or air (by replacing the liquid within the gel pores), known as a hydrogel, oleogel, and aerogel, respectively. An emulsion gel is a gelled matrix filled with emulsion dispersion in which at least one phase, either continuous phase or dispersed phase forms spatial networks leading to the formation of a semisolid texture. Recently, the interest in the application of gels as functional colloids has attracted great attention in the food industry due to their tunable morphology and microstructure, promising physicochemical, mechanical, and functional properties, and superior stability, as well as controlled release, features for the encapsulated bioactive compounds. This article covers recent research progress on functional colloids (emulsion gels), including their fabrication, classification (protein-, polysaccharide-, and mixed emulsion gels), and properties specifically those related to the gel-body interactions (texture perception, digestion, and absorption), and industrial applications. The emerging applications, including encapsulation and controlled release, texture design and modification, fat replacement, and probiotics delivery are summarized. A summary of future perspectives to promote emulsion gels' use as functional colloids and delivery systems for scouting potential new applications in the food industry is also proposed. Emulsion gels are promising colloids being used to tailor breakdown behavior and sensory perception of food, as well as for the processing, transportation, and targeted release of food additives, functional ingredients, and bioactive substances with flexibility in designing structural and functional parameters.

Study on the moving cross‐hatched textures under starved lubrication based on parallel calculation

AbstractThe oil storage effect of textures is beneficial for lubrication performance under starved lubrication. When the larger of the two surfaces in friction pairs is textured, the moving textures should be considered because the boundary conditions are transiently changed at each moment. This is especially for the cross‐hatched textures, which are manufactured on the cylinder liner while not on the piston ring. However, it means that the calculation cost will be very expensive for engineering friction pairs because the required calculation scale is very large and the required time step is very small. So the dynamic characteristics of moving textures on engineering surfaces are normally neglected in the existing researches. In this study, a starved lubrication model of the piston ring‐cylinder liner (PRCL) system is established considering the oil storage effect, local hydrodynamic effect and dynamic characteristics of the moving cross‐hatched textures. To speed up the calculation, an efficient parallel algorithm is developed. The results show that there is a significant difference in minimum oil film thickness (MOFT), wear load and oil film boundaries between stationary textures and moving textures, so the moving textures should not be simplified. This is helpful to find a better design of textures for engineering friction pairs.

Hardness targeted design and modulation of food textures in the elastic-regime using 3D printing of closed-cell foams in point lattice systems

Recently, 3D printing has become an innovative technique in the structuring and modulation of food textures. The objective is to systematically extended 3D food printing to allow the production of cellular structures with specifically targeted textural properties. This study presents an approach for 3D printing structures with predefined hardness. As a step in the foundation of textural design, parameter fitting of 3D printed foams and finite element simulations was used to obtain a generalized hardness design formula for the 3D printing of closed-cell foams. Structures incorporating spherical bubbles arranged in point lattice cubic configurations were printed at different porosity levels. A complete 3D printing-stabilization method was applied with an integrated on-board layer-based heating and optimized for targeting heat induced material transitions to actively modulate the material's mechanical properties. FEM simulations were performed at different Young's moduli adjusted using variable heating speeds where the results showed an independency of hardness on the foam configuration and the distance between the closed-cell bubbles. Comparable hardness results were observed between the 3D printed and simulated samples where the same exponential decrease behavior was achieved. The hardness design formula was developed in relation to the material's Young's modulus, porosity, and printed geometry. The performance of the obtained relation showed comparable results to the FEM simulations and the 3D printed structures. • Texture modulation of foods using 3D printing of closed-cell structures. • 3D printing and porosity variation is applied through spherical bubble designs in cubic configurations. • Manipulation of material mechanical properties is performed using variable in-line thermal stabilization. • Design of textural properties in the elastic regime using FEM simulations and 3D printing.

A quantitative study on planar mechanical anisotropy of a Mg-2Zn-1Ca alloy

A TD-tilted basal texture in Mg alloys often generates a strong planar mechanical anisotropy. Unfortunately, there has been not a quantitative study on this issue. In the present study, the mechanisms for the anisotropy of tensile yield strength in RD-TD plane were quantitatively studied for a Mg-2Zn-1Ca alloy with different grain sizes and textures. Here, RD and TD refer to the rolling direction and transverse direction of the plate. The results show that there is a strong planar yield anisotropy (∼24 ± 5 MPa), regardless of grain size, while this yield anisotropy is absent in texture with a circular distribution of basal poles. The examination of microstructure and X-ray diffraction analysis reveals that, beside basal slip as the predominant mode under both RD-tension and TD-tension, prismatic slip in RD-tension and both prismatic slip and extension twinning in TD-tension are also important. The parameters of Hall-Petch relation are also used to further analyze the mechanism for yield anisotropy. The changeable intercept, σ0, and invariant Hall-Petch slope, k, between RD-tension and TD-tension are rationalized accounting for this anisotropy. The reasons why there are different σ0 and similar k between TD-tension and RD-tension are quantitively discussed. At last, a texture design for decreasing the planar yield anisotropy is given.

Designing a bioinspired scaly textured surface for improving the tribological behaviors of starved lubrication

Scale/scaly structures are commonly seen in living nature, such as loach and pangolin, and they generally play an important role in reducing friction between biosurfaces and their contacted solid/water. Hence, inspired by scale structures in biology, we propose a design of surface texturing with 3D delicate scaly structures to improve the tribological behaviors of mechanical friction interfaces under starved lubrication. Micro 3D metal printing technology was employed to fabricate the scaly textured surface. Experimental tests were performed and the results demonstrated the favorable effect of such bionic texturing on reducing friction coefficient and wear. Furthermore, corresponding FEM simulations and high-speed camera observation confirmed the amplification effect of secondary lubrication and the pre-lubrication effect as the dominating mechanisms.

Tribological Wear Effects of Laser Texture Design on AISI 630 Stainless Steel under Lubricated Conditions

Surface texturing is used in many applications to control the friction and wear behaviour of mechanical components. The benefits of texture design on the tribological behaviour of conformal surfaces are well known. However, there is a big dependency between the geometrical features of the texture and the texture’s performance. In this paper, the effect of laser texturing parameters on textured geometrical features is studied, as well as its role in the tribological behaviour of AISI 630 steel under lubrication and high-contact pressure conditions. The results show a linear impact of the energy density on the surface quality, whereas the scanning speed influences the homogeneity of the sample. Nevertheless, the surface integrity is also affected by the laser parameters, reducing the micro-hardness on the textured area by up to 33%. Friction coefficient average values and stability presented high variations depending on the sample parameters. Finally, the wear mechanisms were analysed, detecting abrasion for the disc and adhesion for the pin.

Optical management for back-contact perovskite solar cells with diverse structure designs

Interdigitated back-contact (IBC) structure design is a promising alternative to further promote the optical absorption and the power conversion efficiency of perovskite solar cells (PSCs). However, their full potential has not been reached owing to the absence of the advanced structure designs and a lack of a deep understanding on the related physics mechanism. In this paper, we proposed three typical IBC configurations featuring flat perovskite layer, textured electron transport layer (ETL) and hole transport layer (HTL), and textured HTL but flat ETL. By the numerical simulations, the optical properties of the three related designs are investigated systematically. The simulation results reveal that anti-reflection coating (ARC) thickness plays an important in determining the device performance and the optimal ARC thickness is suggested to be 70–80 nm. The optimal structure sizes are confirmed by optimizing the structure parameters. In addition, the light-trapping mechanism is clarified by the position-determined photocurrent density and the spatial electric field distributions. Moreover, dependence of optical response under the various perovskite thickness is checked, suggesting that textured IBC structure design is good to achieve high optical absorption. The simulation results demonstrated in this paper provide a valuable guide to design IBC PSCs with high optical performance.

Texture Optimization and Verification for the Thrust Bearing Used in Rotary Compressors Based on a Transient Tribo-Dynamics Model

Abstract Rotary compressors are designed more and more compact, and the compressor cylinder’s ambient pressure is designed very high to facilitate oil separation and improve efficiency. However, these designs cause the working condition of the thrust bearing becoming harsher, and severe wear may occur. The present study is aimed at mitigating its wear condition through surface texturing. Based on a transient tribo-dynamics model considering the coupling effect of the journal and thrust bearings, a texture optimization study for the thrust bearing is conducted, in which three different stochastic optimization algorithms are utilized. The results show that thrust bearings with optimized textures have significantly reduced contact forces and wear under a high working frequency due to an extra hydrodynamic support around the texture dimples. The optimized texture designs are fabricated on the thrust bearing surfaces by a high-accurate picosecond laser machine, and their performance is assessed through experiments using a compressor performance test platform. The experiment results confirm that the textured thrust bearing has a lower wear depth. Moreover, the coefficient of performance (COP) of the testing compressor with textured thrust bearing is increased while its input power decreases, which implies a reduced friction force and a higher energy efficiency.

Experimental and Numerical Assessment on Failure Pressure of Textured Pipelines

Abstract A series of physical tests and finite element (FE) analyses are conducted to evaluate the failure of smooth (conventional) and textured (proposed concept) pipes. To do so, hydrostatic pressure tests are performed on aluminum beverage cans (ductile failure) and additively manufactured Ti6Al4V-0406 titanium pipes (brittle failure). Mechanical material properties are obtained from tensile tests of coupon samples. In the absence of physical burst pressure tests, FE models are validated against experimental results of external pressure tests and are used to predict the buckle initiation (Pi) and burst pressure (Pb) capacity of the textured pipes with different number of circumferential triangles, N, and base angles, α. Results show that buckle initiation pressures of the textured concept is 2.34 and 1.80 times greater than those of the smooth aluminum cans and titanium pipes, respectively. However, the burst pressure of the textured pipe can only get 3% greater than the smooth pipe. Based on the current results, a textured pipe with N = 6 and α = 30 deg is the optimum textured design.

Ray-optics study of gentle non-conformal texture morphologies for perovskite/silicon tandems.

We investigate gentle front side textures for perovskite/silicon tandem solar cells. These textures enhance the absorption of sunlight, yet are sufficiently gentle to allow deposition of an efficient perovskite top cell. We present a tandem solar cell with such gentle texture, fabricated by Kaneka corporation, with an efficiency as high as 28.6%. We perform an extensive ray-optics study, exploring non-conformal textures at the front and rear side of the perovskite layer. Our results reveal that a gentle texture with steepness of only 23° can be more optically efficient than conventional textures with more than double that steepness. We also show that the observed anti-reflective effect of such gentle textures is not based a double bounce, but on light trapping by total internal reflection. As a result, the optical effects of the encapsulation layers play an important role, and have to be accounted for when evaluating the texture design for perovskite/silicon tandems.