Contact Zone Research Articles

Sex chromosome turnover in hybridizing stickleback lineages

Abstract Recent discoveries of sex chromosome diversity across the tree of life have challenged the canonical model of conserved sex chromosome evolution and evoked new theories on labile sex chromosomes that maintain less differentiation and undergo frequent turnover. However, theories of labile sex chromosome evolution lack direct empirical support due to the paucity of case studies demonstrating ongoing sex chromosome turnover in nature. Two divergent lineages (viz. WL & EL) of nine-spined sticklebacks (Pungitius pungitius) with different sex chromosomes (linkage group [LG] 12 in the EL, unknown in the WL) hybridize in a natural secondary contact zone in the Baltic Sea, providing an opportunity to study ongoing turnover between coexisting sex chromosomes. In this study, we first identify an 80 kbp genomic region on LG3 as the sex-determining region (SDR) using whole-genome resequencing data of family crosses of a WL population. We then verify this region as the SDR in most other WL populations and demonstrate a potentially ongoing sex chromosome turnover in admixed marine populations where the evolutionarily younger and homomorphic LG3 sex chromosome replaces the older and heteromorphic LG12 sex chromosome. The results provide a rare glimpse of sex chromosome turnover in the wild and indicate the possible existence of additional yet undiscovered sex chromosome diversity in Pungitius sticklebacks.

At the Heart of the Mothercrystal: Final Fantasy XIV’s Approach to Localization and Lore as a Virtual Contact Zone

<p>Virtual worlds by nature of their persistence and ability to have multiple simultaneous users in the same space can act as contact zones, defined by Mary Louse Pratt as a "social space where disparate cultures meet, clash, and grapple with each other, often in highly asymmetrical relations of domination and subordination," (1991, p. 34). One affordance of virtual worlds in constructing the contact zone is the ability for the developer to use localization to bridge language gaps between a user and the virtual world and, to some extent, between players who have a shared understanding of the virtual world. This understanding extends to the properties of objects and locations and any narrative lore or background in the world. However, localization can be a double-edged sword, with choices in translation and localization leading to confusion among virtual world users and conflict between users and developers. </p><p>Language impacts two aspects of the virtual contact zone. For one, players communicate using languages they are proficient in, using whatever affordances are available in the interface and paratextual platforms, such as the official forums and social mediaplatforms like Reddit and Tumblr. For another, the world itself is awash in language. That text manifests itself in gameplay elements from user abilities and item names to more narrative elements such as character names, dialogue, and written story and worldbuilding elements. These textual and narrative components, called "lore," are essential in contextualizing virtual spaces. Lore helps build the virtual world beyond the actual mechanics and interactions within a virtual space. Lore gives users a sense of not just place but of geography, not just time, but of history, and not just context for players but their place within the story of the virtual world. Lore offers players motivation for playing in addition to traditional gameplay motivators such as exploration, achieving, socializing, and defeating enemies or other players (Yee, 2006; Bartle, 1996) to interact with the world. </p><p>This paper focuses on the case of Final Fantasy XIV: A Realm Reborn (FFXIV), an MMORPG initially released in 2013, its production, approaches to localization,and how it contributes to building a "virtual contact zone." In looking at specific instances where controversies in translation and localization led to confusion and conflict among the participants and developers of the game, this case study illustrates the role of localization in games beyond translation and acculturation. Localization not only serves as the linguistic bridge among members of the contact zone but, in the case of online games where world-building and narrative are important aspects for immersion and play, creates shared experiences and understandings of that virtual world among all members of the virtual contact zone.</p>

Revision of the taxonomic status of Amathuxidia morishitai from Hainan, China (Lepidoptera: Nymphalidae)

Based on the external characters, genital structures, distribution, and intermediate individuals from contact zones, the endemic species Amathuxidia morishitai Chou & Gu, 1994 from Hainan, China is treated as conspecific with A. amythaon (Doubleday, 1847) and is downranked to a subspecies of the latter, i.e., Amathuxidia amythaon morishitai stat. nov. Meanwhile, two subspecies groups of A. amythaon are recognized by morphological and genetic evidence, termed amythaon-group (A. a. amythaon + A. a. dilucida (Honrath, 1884)) and annamensis-group (A. a. morishitai + A. a. annamensis Talbot, 1932) with the latter group showing a deeper divergence than normal on a subspecific level genetically.

Multiple secondary contacts and historic hybridization between glacial lineages of charr (Salvelinus, Salmonidae) in northeastern Asia

AbstractArctic regions of northeastern Asia represent areas of secondary contact of the glacial phylogenetic lineages of charrs belonging to the genus Salvelinus (Salmoniformes: Salmonidae). However, the post‐glacial dispersion of charr across Arctic regions is poorly understood, as knowledge of populations from Chukotka and its neighbouring areas remains limited. Specifically, there is no clear understanding of which charr species inhabit significant regions of Chukotka from the sea coasts to the Kolyma drainage. In this study, we explored the affiliation of lacustrine charrs from the Chukotka area with (1) the Arctic lineage of Taranetz' charr (Salvelinus taranetzi); (2) the Bering lineage of Northern Dolly Varden (Salvelinus malma malma) and (3) the Siberia and Atlantic lineages of Arctic charr (Salvelinus alpinus). We analysed sequence variation of the mitochondrial DNA control region (mtDNA CR; 960 base pairs) and genotyped seven microsatellite loci of nuclear DNA from charr collected at 13 sampling sites. We found different consequences of secondary contact: (1) complete fixation of introgressed mtDNA (mitochondrial capture) and (2) preservation of several mtDNA lineages with the absence of contemporary gene flow between resident populations. Combining the distribution patterns, phylogenetic network topology and knowledge of the glaciation history of the region, we propose two zones of secondary contact of the glacial lineages in Chukotka–Kolima‐Chukotka River system and Paleo‐Amguema River–from where charrs with introgressed genomes spread throughout this range. However, in some cases, the process of foreign mtDNA capture likely occurs in a more localised manner.

Initiation of decohesion between a flat punch and a thin bonded incompressible layer

Non-axisymmetric frictionless JKR-type adhesive contact between a rigid body and a thin incompressible elastic layer bonded to a rigid base is considered in the framework of the leading-order asymptotic model, which has the form of an overdetermined boundary value problem. Based on the first-order perturbation of the Neumann operator in the Dirichlet problem for Poisson’s equation, the decohesion initiation problem is formulated in the form of a variational inequality. The asymptotic model assumes that the contact zone and its boundary contour during the detachment process are unknown. The absence of the solvability theorem is illustrated by an example of the instability of an axisymmetric flat circular contact.

Profiling contact ridge of soft substrates with metallic thin films using a novel interference technique

HypothesisAs technology moves toward flexibility, embedded systems, and miniaturization, which often have metallic elements integrated with the functional substrates, understanding the contact deformation of such soft substrates coated with thin metallic films is crucial. However, probing nanoscale deformations optically, typically in a few hundred nanometers, poses challenges. Dual Wavelength - Reflectance Interference Contrast Microscopy (DW-RICM) holds promise in unveiling nanoscale deformations. However, when paired with conventional glass probes to measure deformation of underlying soft substrates, DW-RICM faces limitations due to light reflection at the glass-air interface, impeding accurate determination of the contact zone (e.g., contact area, contact ridge). Here we hypothesize that using alternative probes to eliminate unwanted reflections can enhance understanding of soft substrate deformation with thin metallic films (bilayer substrates). ExperimentsIn this work, we investigate the deformation profile of viscoelastic soft substrates with sputter-coated gold thin films (referred to herein as bilayer substrates) using DW-RICM. We employ millimeter-sized black ink-coated glass spheres as probes, absorbing most light under DW-RICM. We focus our laser beams associated with DW-RICM at the contact zone between the probe and the underlying soft substrates. FindingsOur new technique of using black ink-coated glass probes in contact with soft bilayer substrates enables us to accurately extract the deformation profile, particularly the contact ridge. With the increase in the gold sputter coating time, the contact area and contact ridge of gold-polymer bilayer substrates decrease. Further, long-term contact analysis of gold-coated soft substrates reveals a steady increase in the contact ridge height over time, unlike the gradual decrease observed in their bare counterparts until reaching a steady state.

Adaptive alien genes are maintained amid a vanishing introgression footprint in a sea squirt

Abstract Human transport of species across oceans disrupts natural dispersal barriers and facilitates hybridization between previously allopatric species. The recent introduction of the North Pacific sea squirt, Ciona robusta, into the native range of the North Atlantic sea squirt, Ciona intestinalis, is a good example of this outcome. Recent studies have revealed an adaptive introgression in a single chromosomal region from the introduced into the native species. Here, we monitored this adaptive introgression over time, examining both the frequency of adaptive alleles at the core and the hitchhiking footprint in the shoulders of the introgression island by studying a thousand Ciona spp. individuals collected in 22 ports of the contact zone, 14 of which were sampled 20 generations apart. For that purpose, we developed a KASP multiplex genotyping approach, which proved effective in identifying native, nonindigenous and hybrid individuals and in detecting introgressed haplotypes. We found no early generation hybrids in the entire sample, and field observations suggest a decline in the introduced species. At the core region of the introgression sweep, where the frequency of C. robusta alleles is the highest and local adaptation genes must be, we observed stable frequencies of adaptive alien alleles in both space and time. In contrast, we observed erosion of C. robusta ancestry tracts in flanking chromosomal shoulders on the edges of the core, consistent with the second phase of a local sweep and a purge of hitchhiked incompatible mutations. We hypothesize that adaptive introgression may have modified the competition relationships between the native and invasive species in human-altered environments.

Distribution, diversity and genetic structure of alders (Alnus lusitanica and A. glutinosa) in Spain

Alders (Alnus spp., Betulaceae) are keystone pioneer species in riparian habitats. In the Mediterranean Basin, where the diploid Alnus glutinosa coexists with the recently discovered tetraploid A. lusitanica, the distribution, diversity and genetic structure of alder species is unknown. The main objectives of this study were to report the distribution of A. glutinosa and A. lusitanica, quantify the local genetic diversity of populations and explore the presence of putative hybrids resulting from the coexistence of A. lusitanica and A. glutinosa individuals in Spain. We assessed 627 individuals from 22 natural alder populations by combining chromosome counts, flow cytometry and microsatellite markers (SSRs) analyses. The ploidy analysis, validated through chromosome counts, revealed the presence of 92 diploid and 535 tetraploid trees from three A. glutinosa and 18 A. lusitanica pure populations, respectively. Notably, no hybrids were detected, not even in Assa, the only population where both species co-occur. The occurrence of mixed ploidy level in alder is reported for the first time in Spain (Assa, Logroño, within the Ebro basin). SSR analysis revealed robust genetic differentiation between the two species and distinctive patterns of variation within A. glutinosa. The high level of differentiation observed was supported by the most probable population clustering determined through pca and structure analyses, along with the identification of a high number of private alleles. For A. lusitanica, the results revealed three distinct genetic groups, geographically distributed. Positive genetic and geographical distance correlations indicated that differentiation could have been driven by isolation by distance. In light of the results, A. lusitanica is the most representative, widespread and genetically variable alder species in Spain, and A. glutinosa is restricted to the north-east of the country. The Ebro riverbank is a contact zone between A. lusitanica and A. glutinosa species, in which no evidence of hybridization was detected yet. Finally, with focus on management, our findings may suggest considering A. lusitanica as a new species, which should be regulated by the forest reproductive material legislation.

A study of fretting fatigue in a contact pair of DZ125/GH4169: its mechanical behavior and life prediction

In this paper, the fretting fatigue test of DZ125/GH4169 contact pair was carried out. Observation and analysis of the wear and fracture were needed to get the fretting damage law. A hardness parameter was introduced to modify the existing life prediction model. The specimen was exposed to both normal and fatigue loads, as indicated by the results, which resulted in the formation of a black oxide layer that stuck to the contact zone's edge. Oxide spalling formed grits and abrasive wear, accelerating the loss of fatigue resistance. At high temperatures, the oxidation was intensified. The life prediction results were all within the double error band. The error range was reduced and the life prediction effect was significantly improved.

Modelling and application of dissolved air flotation for efficient separation of microplastics from sludges and sediments

The pervasive presence of microplastics in our environment necessitates urgent measures to prevent further release and address existing contamination hotspots. This work focuses on the removal of microplastics from sludges and sediments through the application of dissolved air flotation (DAF). In addition to experimental investigations, the study presents the development of a predictive model for the formation of aggregates comprising air bubbles and microplastics in the DAF contact zone. First an empirical model was established to predict the attachment efficiency between air bubbles and particles (αdb). To this end, the experimental attachment efficiency was determined for various plastics, with varying particle sizes and shape factors, and system conditions. The obtained data set was utilized to establish an empirical model by PLS regression describing αdb based on particle size, bubble size, density, Hamaker constant, contact angle, solid load, aspect ratio, circularity, and sphericity, resulting in an MSPE of 0.011 and adjusted-R² of 0.64. Secondly, a semi-deterministic model based on the XDLVO theory was developed using MLR, where αdb was described by the natural logarithm of the Van der Waals, electrostatic and hydrophobic forces acting between the particle and air bubble, and the solid load, with an RSE of 0.067 and adjusted-R² of 0.63. Finally, the applicability of these models was demonstrated in a case study on industrial sludge consisting of sediment and PVC microplastics. Validation of the attachment efficiency and the dimensioning of a DAF unit for processing this sludge at a capacity of 20 m³.h−1 emphasize the practical implications of the developed models.

Simulation Analysis and Experimental Study on the Fluid–Solid–Thermal Coupling of Traction Motor Bearings

The traction motor is a crucial component of high-speed electric multiple units, and its operational reliability is directly impacted by the temperature increase in the bearings. To accurately predict and simulate the temperature change process of traction motor bearings during operation, a fluid–solid–thermal simulation analysis model of grease-lubricated deep groove ball bearings was constructed. This model aimed to simulate the temperature rise of the bearing and the grease flow process, which was validated through experiments. The results from the simulation analysis and tests indicate that the temperature in the contact zone between the bearing rolling element and the raceway, as well as the ring temperature, initially increases to a peak and then gradually decreases, eventually stabilizing once the bearing’s heat generation power and heat transfer power reach equilibrium. Furthermore, the established fluid–solid–thermal coupling simulation analysis model can accurately predict the amount of grease required for effective lubrication in the bearing cavity, which stabilizes along with the bearing temperature. The findings of this research can serve as a theoretical foundation and technical support for monitoring the health status of high-speed EMU traction motor bearings.

SNP‐based analysis of European Thymallus spp. (Salmonidae) reveals extensive mito‐nuclear discordance relevant for biogeographic inferences, taxonomy and conservation

AbstractAimPaleohydrological dynamics are well‐documented for European river systems, promoting shifting phases of isolation and connectivity of their aquatic fauna. These conditions coupled with high rates of hybridisation found in freshwater fishes may introduce considerable complexity and potential mito‐nuclear discordance of phylogenetic patterns. We evaluate this hypothesis using the first large‐scale analysis of nuclear SNPs in European species of grayling (Thymallus) compared to mtDNA data with the aim of reassessing the evolutionary history of this group of rheophilic fishes.LocationFreshwater systems in Europe.MethodsBased on mitochondrial (mitogenomes, control region) and nuclear (ddRADseq) data, we applied population‐genetic, phylogenetic, and biogeographic tools to evaluate lineage diversity in the context of paleohydrological alterations.ResultsThe results corroborated previously recognised high levels of lineage diversity, but revealed several cases of mito‐nuclear discordance and signals of both historical (natural) and human‐mediated introgression among major inter‐ and intraspecific lineages of Thymallus in Europe. A time‐calibrated phylogeny and ancestral area estimation, based on nuclear SNP data, supported a late Pliocene diversification of the genus in Europe and suggested an early colonisation of the Black Sea basin with subsequent dispersal into Central and Western Europe.Main ConclusionsThe genetic structure of Thymallus in Europe recovered by nuclear SNPs contrasts considerably with that supported by mtDNA. Several instances of mito‐nuclear discordance underscore frequent contact of allopatric lineages in a dynamic paleohydrological landscape and reveal the weakness of basing both taxonomic and conservation decisions on inferences based on mtDNA alone. The Danube and Rhine drainages were inferred as important zones of contact between divergent phylogeographic lineages. Additionally, our data cast doubt on the genetic integrity of the endangered T. aeliani. Its divergence from T. thymallus, using nuclear SNPs, appears minimal as samples of T. aeliani group within Danubian lineages, despite carrying highly divergent reciprocally monophyletic mtDNA.

Hydrodynamic processes in designing diamond drilling tools

Relevance. The rational choice of drilling tools is one of the components of a positive result of exploration, mining, drilling operations. The function of a complex solution of problems arising when drilling wells is assigned to a modern drilling tool. Today there is a great variety of designs of rock cutting drilling tools. However, scientific achievements in improving the material and technical production base contribute to the development of drilling technology and creation of new, more efficient tool designs. The most promising and effective in various mining conditions is a diamond drilling tool. During the operation of such a tool, flushing fluid circulation is of great importance, especially in the bottomhole zone of the well being constructed. When designing the structures of a diamond rock cutting tool, it is necessary to take into account not only the strength, cutting, and stabilizing properties, but also the possibility of an effective fluid flow in its circulation system, i.e. without flow energy consumption to overcome resistance, with sufficient capacity for cuttings removal and the necessary level of cooling, lubrication and implementation of other functions of the flushing fluid, which contribute to improving drilling results. At the same time, modern methods of designing a drilling tool should take into account the influence of the drilling fluid, its properties, and the nature of the flow on the rock destruction mechanism, i. e. require a thorough study of the nature of the fluid flow in the contact zone of the tool cutters with the rock. The article proposes the position of considering the design of a diamond drilling tool cutting surface from the point of view of the influence of hydrodynamic processes on the nature of cutters rock interaction. The results of the study of both the author herself and well-known world manufacturers of diamond drilling tools are given as arguments. Aim. To study the influence of the design features of the existing diamond drilling tool on the nature of the fluid flow in the bottomhole zone of the well during drilling. Objects. Designs of diamond drilling tools, hydrodynamic processes associated with drilling. Methods. Analytical method, computer simulation method. Results. Differences in fluid circulation in certain types of diamond drilling tools are determined. The zones of the diamond rock-cutting tool are distinguished. They differ in the nature of the fluid flow. Directions for reducing hydraulic resistance in the bottomhole zone of the well due to changes in the design features of the drilling tool were established.

A Degraded Finger Vein Image Recovery and Enhancement Algorithm Based on Atmospheric Scattering Theory.

With the development of biometric identification technology, finger vein identification has received more and more widespread attention for its security, efficiency, and stability. However, because of the performance of the current standard finger vein image acquisition device and the complex internal organization of the finger, the acquired images are often heavily degraded and have lost their texture characteristics. This makes the topology of the finger veins inconspicuous or even difficult to distinguish, greatly affecting the identification accuracy. Therefore, this paper proposes a finger vein image recovery and enhancement algorithm using atmospheric scattering theory. Firstly, to normalize the local over-bright and over-dark regions of finger vein images within a certain threshold, the Gamma transform method is improved in this paper to correct and measure the gray value of a given image. Then, we reconstruct the image based on atmospheric scattering theory and design a pixel mutation filter to segment the venous and non-venous contact zones. Finally, the degraded finger vein images are recovered and enhanced by global image gray value normalization. Experiments on SDUMLA-HMT and ZJ-UVM datasets show that our proposed method effectively achieves the recovery and enhancement of degraded finger vein images. The image restoration and enhancement algorithm proposed in this paper performs well in finger vein recognition using traditional methods, machine learning, and deep learning. The recognition accuracy of the processed image is improved by more than 10% compared to the original image.

Modeling and experiments on flexible side-electrodes electrostatic actuators: Influence of the contact interface on the available force

This paper presents an in-depth study of electrostatic actuators based on flexible side-electrodes focusing on the available electrostatic force and the derived useful force. A design tool is proposed considering technological aspects as aspect ratio, insulating layer material and voltage level. A space discretized mechanical approach based on Euler-Bernoulli beam theory is developed to model the bending deflection of the flexible movable electrode and “zipping” contact. Analytical developments and simplifications are achieved, rapidly and efficiently implemented in a proposed algorithm. ANSYS® simulations validate the procedure for updating the contact zone through the updating of the electrostatic pressure distribution. Optimum movable electrode width and appropriate “opposable” stiffness for guiding system are discussed. A “residual air thickness” parameter is introduced to address imperfect contact between the electrodes. Experimentalcharacterization studies various prototypes with different structural parameters as thickness (50 µm and 200 µm), gaps (5 µm and 15 µm) and material for insulating layers (silicon oxide and parylene C). The metrology campaign highlights the impact of aspect ratio and oxidation/deoxidation on electrode sidewall quality and hence mechanical performance.A comparison with well-known comb-drive shows higher electrostatic force for flexible side-electrode actuators. As an example, for a 10 µm stroke, the available electrostatic force for flexible electrodes with irregular sidewalls (residual air thickness 0.6 µm) is 2.2 times greater and rises to 7.3 times greater for perfect sidewalls (no residual air).

A New Nephrite Occurrence in Jiangxi Province, China: Its Characterization and Gemological Significance

Nephrite is a very precious gemstone material. As a non-renewable resource, the discovery of new nephrite deposits and the study of the genesis of nephrite have aroused great interest. A new occurrence of nephrite known as Xinyu nephrite was discovered in Xinyu Country, Jiangxi province, China. Field investigations reveal that nephrite appears in a contact zone between the Mengshan composite granitic pluton and Permian carbonate rock. The carbonate rock is calcic marble that underwent diopsidization and tremolitization. Nephrites have a light yellow-green color, weak greasy luster, are slightly-translucent to translucent, and are fine-grained. Their refractive index (RI) ranges from 1.60 to 1.61, and their specific gravity (SG) value ranges from 2.90 to 2.91, falling within the range of nephrites from Xinjiang, China. Their Mohs hardness (Hm) ranges from 5.78 to 5.83. Petrographic observations and electron probe micro analyzer (EPMA) data indicated that analyzed nephrites mainly comprise tremolite, with minor diopside, calcite, quartz, and apatite. Tremolite has a ratio of Mg/(Mg + Fe2+) greater than 0.99. The tremolite grains show microscopic fibrous-felted and columnar textures. Scanning electron microscope (SEM) images show some tremolite fibers interwoven in different crystallographic orientations, and some arranged in parallel. Fourier transform infrared and Raman spectroscopy features reveal the bands of minerals typical for nephrite composition. The petrographic characteristics and geological background of the Mengshan area indicate that nephrite formed through a replacement of calcic marble, which differs from the two known types (D-type: dolomite-related; S-type: serpentinite-related). Mineral replacements were common in nephrite, including diopside by tremolite, calcite by tremolite, and recrystallization of coarse by fine tremolite grains. The discovery of Xinyu nephrite occurrence complements the resource and provides an updated case for the in-depth study of the diversity of nephrite deposits.

Geometric deviation during incremental sheet forming process: Analytical modeling and experiment

Incremental sheet forming (ISF), a promising and flexible forming method, is generally restricted by the unsatisfied geometric deviation for industrial applications; therefore, effective control and accurate prediction of geometric deviation in ISF are essential for quality improvement. However, the geometric deviation in ISF is extremely sensitive to the geometric shape, toolpath, and process parameters, which is challenging to predict and control. In this study, the comprehensive geometric-related mechanisms in ISF were analyzed, including springback after local bending of the bent and contact zones, and the elastic deflection of the inclined wall, particularly the associated deformation in the weak-stiffness region. Through a creative equivalent mapping method for calculating the elastic deflection of complex structures and modeling the bending moment distribution in different zones, an analytical model was developed to accurately and universally predict the geometric deviations of parts by ISF. Based on the results of the experiments and comparative studies using a response surface model, the proposed model provided superior capability for predicting the geometric accuracies of parts made using ISF with different sheet materials, process parameters, and geometric shapes, even for complex parts with non-axisymmetric structures and stepped features. The geometric-related mechanisms, forming characteristics, and influences of crucial parameters in ISF are discussed by adopting an analytical model combined with numerical simulations, demonstrating that the elastic deflection on the inclined wall, particularly the associated deformation in the weak-stiffness region, plays a primary role in the geometric deviation of complex parts compared with other geometric-related mechanisms.

Existence results for variational–hemivariational inequality systems with nonlinear couplings

In this paper we investigate a system of coupled inequalities consisting of a variational–hemivariational inequality and a quasi-hemivariational inequality on Banach spaces. The approach is topological, and a wide variety of existence results is established for both bounded and unbounded constraint sets in real reflexive Banach spaces. Applications to Contact Mechanics are provided in the last section of the paper. More precisely, we consider a contact model with (possibly) multivalued constitutive law whose variational formulation leads to a coupled system of inequalities. The weak solvability of the problem is proved via employing the theoretical results obtained in the previous section. The novelty of our approach comes from the fact that we consider two potential contact zones and the variational formulation allows us to determine simultaneously the displacement field and the Cauchy stress tensor.

Moving contact problem of a functionally graded orthotropic coated half plane

AbstractThis paper develops a frictional moving contact model for a functionally graded (FG) orthotropic layer pressed by a rigid cylindrical punch. The FG orthotropic layer is fully bonded to the isotropic half-plane. The punch moves to the left on the layer at a constant subsonic velocity and a shear stress arises in the contact zone according to the Coulomb friction law. General expressions of displacements and stresses are derived with the help of the Fourier transform and Galilean transformation. Using boundary conditions, the moving contact problem is reduced to a Cauchy-type singular integral equation, the unknowns of which are contact stress and contact width. Gauss–Jacobi integration formula is used to solve the obtained singular integral equation. The effect of some parameters and material properties on the contact width, contact stress and in-plane stress are given in graphical forms and detailed numerical interpretations are presented.

Effects of Pressure Rollers with Variable Compliance in the Microfinishing Process Utilizing Abrasive Films.

This article presents a comprehensive investigation into pressure rollers utilized in the microfinishing process, covering aspects such as design, experimental properties, compliance, and finite element simulation. Prototype pressure rollers with unconventional elastomer configurations were designed and analyzed to explore their effectiveness in achieving superior surface finishes. Experimental analysis and finite element simulations were conducted to gain insights into the performance and behavior of these pressure rollers under various loading conditions. This study addresses the validation of constitutive material models used in finite element simulations to ensure accuracy and reliability. The results indicate that the applied material model, validated through experimental analysis, accurately predicts pressure roller behavior. Finite element simulations reveal distinct contact zone patterns and stress distributions across the contact surfaces, highlighting the importance of considering deflection-induced variations in contact behavior. Additionally, the investigation evaluates the effectiveness of different pressure rollers in removing surface irregularities during the microfinishing process. Roller R3 demonstrates the highest efficacy in removing surface peaks, suggesting its potential for achieving superior surface finishes. Overall, this research contributes to the advancement of microfinishing techniques by providing insights into pressure roller design, performance, and behavior, thereby optimizing microfinishing processes to produce high-quality components. The urgency of this study arises from the growing need for exceptional surface finishes in various industrial sectors. With manufacturing industries increasingly pursuing high-precision components boasting flawless surface quality, the significance of microfinishing processes is highlighted.