Contact Face Research Articles

Effect of repair patch nature on J-integral reduction in notched plates

PurposeThe purpose of this research is to evaluate the effectiveness of different repair patch materials in reducing the stresses at the crack tip of a 2024-T3 aluminum plate. This involves a numerical analysis using the finite element method (FEM) to estimate the reduction in the J-integral value, with the goal of identifying how various parameters related to the patch materials, adhesive properties and loading conditions influence the structural integrity of the repaired plate.Design/methodology/approachThe methodology of this research involves conducting a numerical analysis using the FEM to estimate the reduction in the J-integral value at the crack tip of a 2024-T3 aluminum plate. Three types of patches – metal, composite and functionally graded material (FGM) – were examined under tensile loading conditions, and Adekit-A140 adhesive was used to bond these repair patches to the aluminum plate.FindingsThe analysis considered various parameters, including crack length, the nature of fibers in the composite material, the gradation exponent for FGM patches and the nature of the face in contact with the adhesive for the FGM patch. Additionally, stress analysis was conducted, examining the J-integral values for the plate, shear stress in the adhesive layer and peel stress in the composite patch. The findings highlight that modifying the nature of the repair patch used can significantly enhance the structural integrity of the repaired plate.Originality/valueThe study analyzed J-integral values, shear stress in the adhesive and peel stress in the composite patch. Various parameters, including crack length, fiber type, gradation exponent and adhesive contact face nature, were considered. Results demonstrate that the J-integral value can be significantly reduced by altering the repair patch type, highlighting the effectiveness of customized patch materials in enhancing structural integrity.

High Rate of Return to Sport in Contact and Collision Athletes After Arthroscopic Latarjet With Cortical Button Fixation

Background: Contact and collision athletes face a higher risk of recurrent anterior shoulder instability after surgical stabilization. The Latarjet procedure is often preferred given the high incidence of bony lesions. However, this stabilizing procedure, performed either open or arthroscopically, is met with concerns regarding complications and revision surgery rates. Purpose: To evaluate the return to sport (RTS) and assess complication and instability recurrence rates in contact/collision athletes undergoing the arthroscopic Latarjet procedure using a guided technique with suture buttons for coracoid fixations. Study Design: Case series; Level of evidence, 4. Methods: A retrospective analysis was conducted on contact/collision athletes who underwent the arthroscopic Latarjet procedure for recurrent anterior shoulder instability between January 2011 and March 2018. All patients were operated on arthroscopically using glenoid and coracoid guides and suture button fixation of the transferred coracoid. RTS was defined as the patient being able to participate in his or her activity without any restriction postoperatively. Two independent observers assessed patients using postoperative computed tomography (CT) scans to evaluate coracoid positioning and healing. A multivariate analysis was performed to identify predictive factors associated with persistent apprehension. A group comparison was performed to assess RTS failure risk factors. Results: In 136 contact/collision athletes (mean age, 25 ± 7 years), 93% were satisfied, and 98% achieved shoulder stability at a mean follow-up of 60 months (range, 24-117 months). No suture button–related complications or neurovascular issues were reported. Overall, 82% (112/136) returned to contact/collision sports. The mean time to RTS was 5.3 ± 1.2 months (range, 3-7.3 months). In a CT study performed 2 weeks after surgery, 87% (118/136) of bone grafts were positioned below the equator and 93% (126/136) were flush to the glenoid surface. At the 6-month postoperative CT examination, complete bone block healing was achieved in 84% (114/136). On clinical examination at the latest follow-up, 36 patients (26%) reported some anterior apprehension on testing. On multivariate analysis, patients with severe humeral bone defects (medium to large Hill-Sachs lesions, Calandra grade 2 or 3) had a higher risk of postoperative persistent apprehension. On group comparison, a visual analog scale score >3 and persistent anterior apprehension were found to be associated with failure of RTS. Conclusion: The arthroscopic Latarjet procedure with suture button fixation allowed 82% of athletes with recurrent anterior shoulder instability to return to contact or collision sports. Patients with severe humeral bone defects have a higher risk of persistent anterior apprehension and decreased RTS. The arthroscopic-guided procedure with suture button fixation is safe; accurate, with a high rate of anatomic graft positioning and healing; and reliable, with a low recurrence rate.

On-Demand Elongation of Peptide Nanofibrils at Cellular Interfaces to Modulate Cell-Cell Interactions.

Natural cells can achieve specific cell-cell interactions by enriching nonspecific binding molecules on demand at intercellular contact faces, a pathway currently beyond synthetic capabilities. We are inspired to construct responsive peptide fibrils on cell surfaces, which elongate upon encountering target cells while maintaining a short length when contacting competing cells, as directed by a strand-displacement reaction arranged on target cell surfaces. With the display of ligands that bind to both target and competing cells, the contact-induced, region-selective fibril elongation selectively promotes host-target cell interactions via the accumulation of nonspecific ligands between matched cells. This approach is effective in guiding natural killer cells, the broad-spectrum effector lymphocytes, to eliminate specific cancer cells. In contrast to conventional methods relying on target cell-specific binding molecules for the desired cellular interactions, this dynamic scaffold-based approach would broaden the scope of cell combinations for manipulation and enhance the adjustability of cell behaviors for future applications.

Exploring tunable optoelectronic properties of two-dimensional GaS/PtSSe heterostructures under biaxial strain and external electric field

Vertically stacked heterostructures offer novel material options for designing tunable optoelectronic devices due to their adjustable electronic and optical properties. This work compares the electronic structure, charge transfer, and optical properties of two different contact faces of GaS/Janus PtSSe heterostructures using the density functional theory. The results show that GaS/PtSSe form a built-in electric field at the interface, directing from the monolayer GaS to the PtSSe. GaS/SePtS and GaS/SPtSe are determined to be indirect bandgap semiconductors with bandwidths of 1.51 eV and 1.11 eV utilizing the PBE. In this study, the band alignment of GaS/PtSSe can induce a semiconductor-to-metal transition. Notably, GaS/SePtS is highly sensitive to biaxial strain and external electric field, transitioning its energy band alignment from Type-I to Type-II. Applying tensile strain enhances the sunlight absorption of GaS/PtSSe, making it a promising candidatein the tunable electronic devices and photodetectors.

Analysis of Thermoelastic Contact of Gas-Lubricated Rough Sealing Faces.

Friction and wear are the main failure sources of face seals. When the surfaces of sealing rings exhibit greater roughness, the level of friction might increase and lead to sealing failure. Therefore, in this paper, based on the elastic contact hypothesis of rough and wavy surfaces and the influence of temperature on the elastic modulus of materials, a thermoelastic contact lubrication model of a gas-lubricated end seal is established. The novelty and advantage of this study is that it takes the effect of surface roughness into consideration during thermoelastic analysis of gas-lubricated seals. The film pressure, temperature, contact force and deformation of a gas spiral groove-faced seal are numerically determined. The influence of surface roughness on the contact distribution, deformation and temperature of the end-face seal at different speeds and pressures is analyzed. The film thickness increases as the rotational speed increases from 1 rpm to 2000 rpm, while the contact pressure sharply decreases from 0.25 kPa to 0. The analysis shows that the roughness contact mainly happens on the inner side of the rings due to convergent distortion of the seal faces, which easily causes partial wear of the seal faces. Moreover, it can also be found that the spiral grooves on the sealing surface can produce obvious hydrodynamic pressure effect due to the function of shear speed when the speed increases to 2000 rpm, while the film temperature increases from 293.3 K to about 306 K. The greater surface roughness results in a larger temperature rise under low-rotational-speed and lower-seal-pressure conditions, which further increases the risk of severe wear or even failure of the seal faces.

Superior tribological and sealing performance of micro-crystalline diamond coated silicon carbide seals under dry friction and high load

Silicon carbide seals suffer severe wear under the conditions of dry friction and high load, posing a great challenge in achieving a stable performance and a long lifetime. In this work, micro-crystalline diamond coatings were deposited on silicon carbide sealing rings to prevent the failure caused by wear. The deposited micro-crystalline diamond coatings exhibit high-quality crystallinity and strong adhesive strength with the silicon carbide substrate. In sealing tests, the micro-crystalline diamond coated silicon carbide sealing pair demonstrates superior tribological and sealing properties under dry friction and high load of 1800 N, featuring a low coefficient of friction of 0.16, a low wear rate of 4.00 × 10−7 mm3·N−1·m−1 and a high friction limit of 5.24 MPa·m·s−1. Characterizations of morphology, chemical composition and microstructure confirm that the smoothening effect on the contact face and the formation of graphite during the sealing test synergistically contribute to the outstanding tribological and sealing performance.

The two faces of secondary contact on islands: Introgressive hybridization between endemics and reproductive interference between endemics and introduced species

AbstractAimHybridization is thought to have played an important role in shaping the evolutionary history of diverse island taxa. Here, we propose an ecological and evolutionary framework for understanding the causes and consequences of heterospecific mating on islands—with and without introgressive hybridization. We use this framework to support our main contention that cases of secondary contact among endemic species should commonly result in introgressive hybridization whereas cases of contact between endemic and introduced species should commonly result in reproductive interference (RIN)—resulting in two qualitatively different faces of secondary contact on islands.LocationCanary Islands, Galapagos, New Zealand, Caribbean and Hawaii.Taxa705 vertebrate, invertebrate and plant species spanning 167 genera and 99 families.MethodsUsing a quantitative analysis of empirical research on secondary contact on islands, we weigh evidence for the causes and consequences of secondary contact and heterospecific mating on islands. In particular, we compare cases of secondary contact between endemic species versus secondary contact between endemic and introduced species.ResultsWe find that the drivers of secondary contact and heterospecific mating on islands most frequently reported in the literature are disturbance, long‐distance (e.g. inter‐island) dispersal and compromised assortative mating. We find support for the hypothesis that extensive introgression is a more common outcome between endemic species while RIN is a more common outcome between endemic and introduced species.Main ConclusionsWe conclude that there are biological reasons to predict secondary contact and heterospecific mating to be common on islands for all taxa, but that the consequence of secondary contact is categorically different for contact between endemic species and contact between endemic and introduced species. We conclude that the former likely explains the apparent frequency of hybridization on islands, while the latter presents a cryptic and underappreciated conservation threat.

Hindi, Polish and translation. Faces of language contact in the contemporary English

Hindi, Polish and translation. Faces of language contact in the contemporary English

Self-reported eye contact sensitivity and face processing in chromosome 22q11.2 deletion syndrome

ABSTRACT Introduction 22q11.2 deletion syndrome (22qDS) has been associated with varying levels of social impairments, and with atypical visual scanning of faces. The present study explored whether self-reported sensitivity to eye contact might be related to these phenomena. Method Individuals with confirmed 22qDS were interviewed about their experience and possible discomfort with eye contact. In cases where individuals expresesed discomfort, they were subsequently asked about coping mechanisms used to deal with this discomfort. In addition to self-reported eye contact discomfort, gaze to emotional faces was examined using eye tracking. Results In the subgroup of individuals who reported discomfort during eye contact, eye tracking results revealed a lower amount of gaze in the eyes of neutral faces, as well as the absence of the typical left visual field (LVF) bias, indicative of alterations in hemispheric lateralization. This subgroup also scored lower on a measure of everyday functioning. Conclusions Our results show that, by simply asking individuals with this social and communicative disorder about eye gaze discomfort, we may better understand the specific challenges that they experience. Moreover, information gained from such first-person reports together with eye-tracking measures further informs about the integrity of their face processing system, as well as about the nature and degree of impairment in this population.

High-efficiency electromagnetic interference shielding and thermal management of high-graphene nanoplate-loaded composites enabled by polymer-infiltrated technique

Polymer composites embedded with high filler loads (≥50 wt%) are urgently needed to address the electromagnetic interference (EMI) shielding and thermal barrier problems for the high-power integrated electronic devices. However, designing polymer composites with high filler loads remains a challenge due to difficulties in processability and poor flexibility. Herein, high graphene nanoplates-loaded polyurethane (GNP/PU) composites were enabled by a tractable and scalable polymer-infiltrated technique, in which GNPs were in compact contact face to face and arranged along the in-plane direction. The formation of such structure provided good channels for the transmission of electrons and phonons in the GNP/PU composites. Impressively, the GNP/PU composites showed strong EMI shielding and thermal conductivity, with a superior EMI shielding effectiveness of 67.6 dB (0.4 mm thickness), and extremely high thermal conductivity of 41.60 W/(m·K). Moreover, the GNP/PU composites were proven to have excellent mechanical flexibility, EMI shielding stability, and thermal management capability. With good comprehensive performance and high processability, the GNP/PU composites hold great promise for EMI shielding and thermal management applications in the field of highly integrated electronics.

Meshing theory of face worm gear drive with hardened cylindrical worm

This article proposes a novel linear contact face worm gear drive. The novel face worm gear drive consists of a face worm gear and a cylindrical worm enveloped by a tapered surface. The meshing theory for the novel face worm gear drive is systematically built up. The meshing theory on the base of the reference point is further developed aimed at the worm pair where the indexing surfaces are planar and cylindrical. The design methods of the rough size for the face worm gear are introduced. The computing method for the worm limit axial mounting distance is presented by employing the meshing limit line function. The asymmetry of the tooth surfaces for the worm pair is evaluated using the helix angle at the midpoint on the line of section for the worm gear tooth surface and the tooth profile angle for the worm axial section. Numerical results show that the geometric characteristics and the meshing properties for the tooth surface on both flanks of the novel face worm gear drive are asymmetrical. However, the meshing properties for the novel face worm gear drive are satisfactory.

Simultaneous Treatment of Both Sides of the Polymer with a Conical-Shaped Atmospheric Pressure Plasma Jet.

A conical-shaped atmospheric pressure plasma jet (CS-APPJ) was developed to overcome a standard limitation of APPJs, which is their small treatment area. The CS-APPJs increase the treatment area but use the same gas flow. In the present work, polypropylene samples were treated by CS-APPJ and characterized by scanning electron microscope (SEM), the contact angle, Fourier-transformed infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). It was observed that the treatment co-occurs on the face directly in contact with the plasma and on the opposite face (OF) of the samples, i.e., no contact. However, the treatment changed the chemical composition on each side; the OF is rougher than the direct contact face (DCF), probably due to the oxygen groups in excess at the DCF and nitrogen in quantity at the OF. Although simultaneous treatment of both sides of the sample occurs for most atmospheric plasma treatments, this phenomenon is not explored in the literature.

Experimentally Based Numerical Simulation of the Influence of the Agricultural Subsurface Drainage Pipe Geometric Structure on Drainage Flow

The geometric structure of corrugated plastic pipes affects performance in agricultural subsurface drainage systems. To explore the influence of pipe geometry on flow field characteristics and the characterization of water movements, we developed a three-dimensional (3D) steady-state subsurface drainage model based on computational fluid dynamics (CFD). An analysis of the CFD and sand tank results indicated that the proposed model can accurately simulate the subsurface drainage process (R2 = 0.99). The corrugation structure parameters of the drainpipe, including the outside diameter, corrugation valley width and corrugation height, were taken as the objects for this study, and the influence of corrugation parameters on drainage discharge was orthogonally analysed. During drainage, the soil water initially collects in the corrugation valley and then approximately ninety percent of the water flows into the pipe through the bottom perforations; increasing the contact face area between the corrugation valley and soil can increase the flow rate of the drainpipe and the water table height above the pipe, which decreases the intersection position of the pipe and water table. The results of the analysis of the range and variance of the orthogonal experiment showed that the order of the primary and secondary factors influencing the drainage discharge was the outside diameter, corrugation valley width and corrugation height, with the outside diameter being most critical influencing factor.

Thermal–mechanical model for machining with chamfered insert considering tool flank wear

The deformation of material leads to severe thermal–mechanical effects during metal cutting with chamfered insert. The high cutting temperature on the contact face results in the wear of the insert which is a critical issue. However, there is still a lack of a comprehensive understanding of thermal–mechanical effects, especially with respect to the presence of the tool flank wear. To address this, an analytical thermal–mechanical model is developed in this paper for the prediction of the temperature distribution with a worn insert based on a modified slip-line field approach. Firstly, an analytical slip-line field model is introduced based on material plasticity and plowing theory considering the tool flank wear. The structure of the slip-line field model, especially at the dead metal zone and the flank zone, is modified to reveal the material flow mechanism. Then, heat sources, including primary heat source, secondary heat source, tertiary heat source, and fourth heat source, are clarified to explain the heat generation phenomenon in the cutting process. In addition, a cutting temperature field model is developed to show the effect of tertiary heat source based on the imaginary heat source theory. Finally, the slip-line field geometry and temperature distribution are extracted from two-dimensional finite element simulation to verify the proposed model. And orthogonal experiments are carried out for measuring the maximum cutting temperature. The good agreement of predicted results, simulated results, and experimental results verifies the accuracy of the proposed model.

A model for fretting contact of layered materials with interfacial cracks

Surfaces of tightly fitted joints such as splines and dovetails in aero-engines are expected in nominally static contact but experience small amplitude oscillations in practice, leading to fretting fatigue due to nucleation and propagation of micro-cracks. Modern surface coatings are designed to improve the anti-friction/wear capabilities but result in severe stress concentrations across the bonding interfaces due to property mismatch, which may generate interfacial cracks and lead to delamination damage. In this study, a numerical model is developed to investigate the fretting behavior of layered materials with mixed-mode I and II cracks at the layer/layer/substrate interfaces in plane-strain conditions. The layer-type impurities are assumed as a bunch of inclusions, whilst the crack-type ones are simulated as discrete edge dislocations. The governing equations are established based on the analysis of stress state, and the impurity-induced displacement is taken into account for an accurate description of the fretting contact. The intensive interactions in the contact system are determined by a multi-loop algorithm, and the calculation efficiency is improved by using the Fast Fourier Transform (FFT) technique. The model can be easily handled without refining meshes near the crack tips, and the calculation time is far less than that of the finite element model to achieve comparable solutions. The model is also capable of simulating cracks with their faces in contact by disabling the loop that determines the mode I crack solution. Details are discussed on the surface traction and subsurface stress influenced by layer films and embedded cracks. The solutions to crack-face displacement are also presented to reveal the potential crack patterns enforced by the time-dependent contact loading. The conclusions are expected to provide insights into enhancing the damage resistance of surfaces suffering from fretting.

The two faces of secondary contact on islands

The two faces of secondary contact on islands

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.

Information sharing across mental health service providers and criminal legal system stakeholders: Perspectives of people with serious mental illnesses and their family members

ObjectiveThe overrepresentation of people with serious mental illnesses in the criminal legal system has spurred information-sharing initiatives to transmit information between mental health service providers and criminal legal system stakeholders with the goal of improving resources and streamlining access to care. However, no research to date has examined the perspectives of people with mental illnesses who have their information shared across these systems or the perspectives of their family members. This study examined the perspectives on mental health-criminal legal system information sharing among people with serious mental illnesses and a history of arrest, as well as their family members. MethodsResearchers interviewed 24 clients with serious mental illnesses and a history of arrest who are enrolled in a randomized, controlled trial of a police-mental health Linkage System as well as 11 of their family members. Participants were recruited and interviewed between November 2020 and February 2021. A thematic analysis was used to code and analyze all interview transcripts. ResultsStudy participants articulated perceived benefits and concerns around cross-system information sharing. There was strong support for information sharing in both directions, with the anticipation that such information sharing can prevent unnecessary arrest and/or incarceration, promote positive and safe interactions with criminal legal system professionals, and foster greater understanding and access to treatment. Concerns were more limited and largely related to perceived stigma around mental illnesses and the potential consequences of such stigma. ConclusionsWhile concerns about information sharing should be considered, study participants overwhelmingly perceived the sharing of information between mental health providers and criminal legal stakeholders as a positive intervention. Such perspectives can be understood as a pragmatic choice in the face of criminal legal system contact and additional research could guide programmatic and policy changes.

Transducer Design for Clamp-on Guided Wave Flow Measurement in Thin-Walled Pipes

Clamp-on ultrasonic transit time difference flow meters provide opportunities for metering where it is impractical or undesirable to cut into an existing pipeline to install an alternative flow meter. Up until now, it has been difficult to perform this type of measurement on thin-walled metal pipes, due to the difficulty of interpreting the guided wave modes in the combined pipe wall and internal fluid system, but a new method has been reported recently that utilises these guided wave modes for flow measurement. Through computational modelling, and construction and testing of different transducers, the design considerations for clamp-on transducers are highlighted and their impact on guided wave flow rate measurement is evaluated. The design features considered include a curved contact face to provide focusing of the ultrasound within the pipe and a scattering surface to reduce internal reflections. It is found that additional unwanted ultrasonic modes can be minimised by ultrasonic transducer wedge design features such as profiling the curvature of the transducer to conform to the pipe wall or creating a scattering edge to minimise internal wedge reflections. It is also observed that minimising these unwanted modes does not offer any advantage for the transit time difference measurement used in calculating flow.

Spiritual Humanism: A Call to Creativity in Sufi Studies

Chinese philosopher Tu Weiming (1940-) has spent a lifetime in dialogue with cultural and spiritual traditions beyond the sanjiao or ‘three religions’ (Confucianism, Daoism, Buddhism) of the Sinic world. This engagement has included sustained intercourse with the Abrahamic monotheisms and Hellenic philosophy, Hinduism and Indian spirituality, and a variety of indigenous heritages. The outcome of such cross-cultural ferment has been the elaboration of a ‘spiritual humanist’ alternative to the secular humanism of post-Enlightenment modernity. We begin by introducing Tu’s concept of Spiritual Humanism in general and his engagement with the Islamic world in particular. Adonis is then identified as a natural ally; his Sufism and Surrealism is presented as a case study in Spiritual Humanism with obvious relevance for Sufi Studies. Contemporary Sufi Studies discourse, this paper ultimately argues, should likewise not restrict itself to hermetic philological analyses of traditional sources; following Adonis’s example in Sufism and Surrealism, it should embrace the creative reelaboration of this tradition in the face of contact with new stimuli. Tu’s Spiritual Humanism is both one such stimulus and an active Confucian embodiment of this spirit of creativity.