Contact Analysis Research Articles

Adhesive contact mechanics of penta-twinned nanowires

Penta-twinned nanowires, made of silver, gold, or copper, are envisioned to enable many applications, most notably stretchable and flexible electronics. In several instances of analysis of their behavior for device design, such as heat transfer due to current-induced heating, adhesion to substrates, or adhesion of nanowires to each other in conductive networks, knowledge of variables related to the mechanics of their contact is needed, for example the contact area (or radius). Due to the nanowires’ change in cross section, from circular to rounded-pentagonal as diameter increases, adhesive contact analysis is complex, and up to now has been simplified to assume either circular or perfect pentagonal cross sections. Here, we analyze the adhesive contact of the nanowires, fully considering the complexity of the cross section. We present equations to describe the geometry of the cross-section as it decreases in roundness with increasing diameter, finite element simulations that include elastic anisotropy and Lennard-Jones adhesive interactions, and observations on the adequacy of simplified contact models in describing the behavior. Calculations are presented for contact to typical stiff (silicon) and compliant (PDMS) substrates. The results reveal that, contrary to previous assumptions, the nanowires do not conform to the behavior of a perfect pentagon for the diameters typically encountered experimentally, and the roundness of the cross-section remains a factor that reduces the contact area. This reduction depends on the stiffness of the contact, being greater for stiff substrates.

In silico analysis of TRPM4 variants of unknown clinical significance

Background TRPM4 is a calcium-activated channel that selectively permeates monovalent cations. Genetic variants of the channel in cardiomyocytes are associated with various heart disorders, such as progressive familial heart block and Brugada syndrome. About97% of all known TRPM4 missense variants are classified as variants of unknown clinical significance (VUSs). The very large number of VUSs is a serious problem in diagnostics and treatment of inherited heart diseases. Methods and results We collected 233 benign or pathogenic missense variants in the superfamily of TRP channels from databases ClinVar, Humsavar and Ensembl Variation to compare performance of 22 algorithms that predict damaging variants. We found that ClinPred is the best-performing tool for TRP channels. We also used the paralogue annotation method to identify disease variants across the TRP family. In the set of 565 VUSs of hTRPM4, ClinPred predicted pathogenicity of 299 variants. Among these, 12 variants are also categorized as LP/P variants in at least one paralogue of hTRPM4. We further used the cryo-EM structure of hTRPM4 to find scores of contact pairs between parental (wild type) residues of VUSs for which ClinPred predicts a high probability of pathogenicity of variants for both contact partners. We propose that 68 respective missense VUSs are also likely pathogenic variants. Conclusions ClinPred outperformed other in-silico tools in predicting damaging variants of TRP channels. ClinPred, the paralogue annotation method, and analysis of residue contacts the hTRPM4 cryo-EM structure collectively suggest pathogenicity of 80 TRPM4 VUSs.

Parametric Study of the Effect of Diameter-to-Thickness Ratio Against Bending and Shear Load on the Behavior of Round Hollow Structural Section Beam

The steel-constructed buildings in Indonesia are on the rise, indicating a growing preference for their durability and versatility in construction projects. This led to the general application of Round Hollow Structural Section (Round HSS) as column and beam elements. Therefore, this study aimed to conduct parametric analysis of the effect of Diameter-to-Thickness Ratio (D t-1) on the three-point and four-point flexural analysis of Round HSS beam using MSC Marc/Mentat software. Nonlinear materials and geometries were employed, along with the application of contact analysis, with contacted and contacting bodies. Moreover, the load and boundary condition were set to be similar to the experiment. The results showed that a greater D t-1 led to the possibility of withholding a smaller load and causing smaller displacement in Group A with fixed diameter and different thickness values. Meanwhile, in Group B with fixed thickness but different diameters, a greater D t-1 led to the potential of restraining more load and experiencing smaller displacement. All specimens from both groups were observed to have failed due to a combination of global and local buckling at the right location under the load applied. AISC bending moment calculated was found to be greater than the values obtained from the finite element analysis for all sections under three-point loads. It was also discovered in the four-point flexural analysis that the bending moment of noncompact section was greater than for AISC while those for the compact section were lower. Furthermore, shear strength (Vn) calculated was observed to be greater thanshear force from finite element analysis (Pmax/2).

Effect of CNT radius on flattening contact behaviour of CNT-Al nanocomposite: A numerical approch

In the present paper, a flattening contact analysis of CNT-Al nanocomposite is presented for both loading and unloading phases. APDL code is used in ANSYS framework to create the FE model to analyse the contact behaviour between a frictionless cylinder (CNT-Al) and a rigid flat. The developed model has been validated against established results of certain problems with lesser complexity. The contact force, contact area, von Mises stresses and nodal displacements are extracted from the simulated solution. These parameters are noted at the end of the loading step and also once unloading is completed from a certain interference. It has been found that as CNT radius increases, the contact properties get decreased. It's also observed that beyond a certain CNT radius, the contact properties of CNT-Al nanocomposite materials start to resemble those of the matrix material and eventually fall below the matrix material.

A Novel Tooth Modification Methodology for Improving the Load-Bearing Capacity of Non-Orthogonal Helical Face Gears

This study proposes a double-crown tooth surface modification technology that improves the load-carrying capacity of non-orthogonal helical tooth surface gears. The tooth modification is determined by a modified rack-cutter, and its feed motion is related to an intentionally designed transmission error. The novelty of the tooth modification design is that the transmission error can be pre-designed. First, changing the tooth profile of the tool enables preliminary modification along the tooth profile direction; second, by modifying the interaction between the tool and the machined gear, subsequent fine adjustments are made to the contact path. This two-stage tooth modification strategy not only retains the advantages of the traditional method but also significantly improves the balance of the load distribution on the tooth surface through an original contact path modification strategy. Through systematic tooth contact analysis (TCA) and loaded tooth contact analysis (LTCA), it was verified that the new method reduces contact stress and tooth root bending stress and improves the gear’s resistance to misalignment errors. This research provides the basis and motivation for further exploring and improving this tooth profile modification technology to solve the challenges faced by more complex gear systems.

Asperity contact analysis: coupling effects of normal interference and nanoscale offset by molecular dynamics simulations

This work investigates the offset contact behaviors of nanosized asperity with spherical and non-spherical shapes, aiming to provide a more realistic analysis of asperity contact for rough surfaces. Molecular dynamics models of nanosized asperity are established, using diamond and copper as exemplary materials. Differences between offset and non-offset contacts, as well as spherical and non-spherical asperities are compared through atomic variations including displacement, shear strain and structure. Coupling effects of normal interference and nanoscale offset on asperity contact behaviors are further analyzed. Comparisons between the established models and the microscopic asperity models in contact force-interference dependence are conducted for verification. Results indicate that atoms in central contact region move vertically with smaller shear strains, while those in peripheral region primarily move diagonally outward with larger shear strains due to directional atomic slip motion. Furthermore, the spherical asperity shows higher atomic deformation and contact force compared to the non-spherical asperity for identical interference and offset conditions. Additionally, the shear resistance of single-crystal copper with {100} crystal orientation can be enhanced along the [1 1 0] and [1 − 1 0] directions.

Wear characteristics analysis of variable hyperbolic circular-arc-tooth-trace cylindrical gear transmission considering assembly error theory

Wear is the main failure form of the gear transmission interface, runs through the whole life cycle of gear service, and the distributed error of the tooth surface due to the introduced assembly error will make the actual meshing state of the tooth surface different from the ideal meshing state, thus affecting the tooth surface wear trajectory and state. Therefore, considering the coupling relationship between assembly error and tooth surface contact analysis, the variation laws of the wear amount of the gear transmission interface of the variable hyperbolic circular-arc-tooth-trace cylindrical gear were studied under the consideration of assembly error in this article. Based on the tooth surface contact analysis method and Hertz contact theory, the transient linear load, the combined radius of curvature, the length axis and short axis of the contact ellipse, and the instantaneous sliding velocity were calculated. Through revising the calculation method of adhesive wear of variable hyperbolic circular-arc-tooth-trace cylindrical gears, the correlations between the tooth surface wear amount and gear parameters of variable hyperbolic circular-arc-tooth-trace cylindrical gears under different assembly errors were analyzed. The results show that the maximum wear occurs at the root of the tooth, and the wear at the indexing circle approaches zero, whether it is standard installation or non-standard installation. The vertical axial error and horizontal axial error have little effect on the wear, while the center distance error will aggravate the wear. The proposed method comprehensively considers the influence of assembly error and gear parameters on tooth surface wear, and this method can provide a theoretical reference for the design and analysis of anti-wear, wear reduction, and life extension of variable hyperbolic circular-arc-tooth-trace cylindrical gear tooth surface.

Crystal structure of 1-(E)- [(5‑bromo-2-hydroxybenzylidene amino) pyrrolidin-2-one]: Design, synthesis and computational evaluation of a novel racetam congener for epilepsy

The present investigation illustrates the conceptualization, synthesis, crystallographic analysis, and computational assessment of a new racetam derivative with a pyrrolidone ring as the pharmacophore. The compound demonstrates drug-like characteristics similar to LEV, an approved anti-epileptic drug, indicating its potential for developing novel epilepsy drugs. Molecular docking and molecular dynamic simulations were used to evaluate the binding affinity between the compound and SV2A, a protein-ligand complex. The protein-ligand complex attained structural equilibrium in the final 50 nanoseconds of the 200 nanosecond molecular dynamics simulation. The analysis reveals that regions with higher flexibility are primarily located in the extramembrane regions of the protein. Intermolecular contact analysis reveals hydrogen bonding and hydrophobic interactions as the primary types of interactions. The Molecular Mechanics Poisson-Boltzmann Surface Area (MMPBSA) calculation highlights the energetic aspects of ligand binding and the participation of important residues in the binding pocket. Unique interactions like those involving bifurcated hydrogen bonding, and novel pi-anion interaction makes the study significant. Quantum chemical calculations for the compound (LIG) done using DFT corroborates the protein-ligand interactions on the basis of Molecular Electrostatic Potential (MEP) maps. The study establishes the structure-activity relationship (SAR) of the newly developed pyrrolidone-based compound, identifying it as a promising lead molecule for epilepsy treatment.

The Inhibition Mechanism of Pancreatic Ductal Adenocarcinoma via LXR Receptors: A Multifaceted Approach Integrating Molecular Docking, Molecular Dynamics and Post-MD Inter-Molecular Contact Analysis.

Pancreatic ductal adenocarcinoma (PDAC) has an unfavorable outlook due to its aggressive characteristics, delayed diagnosis, and limited effective treatment options for advanced stages of the disease. The significant mortality rate has prompted investigations into additional factors that could aid in managing this type of cancer. Liver X receptors, specifically LXRα and LXRβ, are nuclear receptors that oversee the expression of genes related to cholesterol, glucose, lipid metabolism, and inflammatory responses. LXRs have also emerged as potential targets for addressing PDAC, and recent findings have demonstrated that LXR ligands can impede cell proliferation in various cancer forms, notably pancreatic cancer. This comprehensive computational research study involving oncological in silico mechanism discovery explored inhibitory ligands for Liver X receptors (LXRα and LXRβ), which are believed to have prognostic significance in PDAC. The study utilized Baicalein, Beta-Sitosterol, Polydatin ligands in molecular docking and dynamics and post-molecular Hydrogen bonding contact analyses dynamics to characterize receptor inhibition. The outcomes suggest that Baicalein exhibits versatile inhibitory effects on both receptors, while Beta-Sitosterol emerges as a highly effective inhibitor of LXRβ. Further in vitro and in vivo investigations will be beneficial and would shed light onto the mechanism to decipher the suppression of PDAC evaluating the potential of Baicalein, Beta-Sitosterol, Polydatin natural ligand compounds.

Contact Analysis for Cycloid Pinwheel Mechanism by Isogeometric Finite Element

Cycloid drives are generally used in precision machinery requiring high-reduction ratios, such as robot joint (RV) reducers. The contact stress of cycloidal gears greatly affects lifetime and transmission performance. Traditional finite element method (FEM) has less computational efficiency for contact analysis of complex surface. Therefore, in this paper, isogeometric analysis (IGA) was employed to explore the multi-tooth contact problem of the cycloid pinwheel drive. Based on the nonuniform rational B spline (NURBS) curved surface generation method, the NURBS tooth profile of the cycloid gear was reconstructed. In addition, the NURBS surface of the cycloid gear–pin tooth–output pin was generated via the element splicing method. A geometrical analysis model of cycloid pinwheel drive was established to solve the contact force of the meshing pair under different input angles and compared with the finite element method in terms of convergence, resultant accuracy, and solving timeliness. The results show that isogeometric analysis has higher accuracy and efficiency than the finite element method in calculating the contact stress and contact force. The error of the IGA is only 8.8% for 10 × 10 elements in contact, while the error of the finite element method reaches about 40%. The method can improve the contact simulation accuracy of the cycloid drive and provides a reference for the design evaluation of RV reducer.

Technological and contact analysis of Hirth joints including manufacturing tolerances

The present work proposes a novel method for determining the influence of the machining tolerances on the effective contact area of Hirth joints. The proposed method is based on a general Finite Element Model (FEM) capable to simulate any meshing condition of Hirth joints including positioning and machining tolerances using the Monte Carlo method. The FEM was developed based on an accurate measurement campaign of several Hirth joints which allowed to determine the geometric parameters affecting the meshing and the related ranges of variation. The machining reference surfaces and the sequence of technological processes which produce the Hirth joint starting from a raw disc were identified through contactless measurement techniques. The related machining tolerances were measured by employing a high-precision Coordinate Measuring Machine (CMM). A mean value and a standard deviation were associated with each geometrical parameter of the joint. The proposed method can be used for the preliminary design and the quality check of the Hirth joint. In particular, the Prussian blue test, which represents the typical test used to verify the joint’s compliance with the technical specification, was simulated. The results highlight the reduction of the effective contact area of the Hirth joint due to the presence of manufacturing tolerances, which can lead to worse mechanical performances and early failure, and could be used to define the machining tolerances limit of Hirth joints.

Thermoelastoplastic hydrodynamic lubrication contact analysis of three dimensional rough tooth surface considering micro-scale effect and thermal effect

The contact properties of gear rough surfaces during meshing are influenced by various factors. The analysis of rough surface thermoelastoplastic hydrodynamic lubrication (TPEHL) considering micro-scale effect and thermal effect has not been addressed in the literature. This study establishes a new TEPHL model with multi-factor coupling of thermal field, fluid lubrication, stress-strain, and geometric profile. Based on strain gradient theory (SG), a new thermoelastoplastic material constitutive considering micro-scale effect is developed. Subsequently, the three-dimensional rough surface TPEHL-SG analysis of gear is conducted. The paper investigates the impact of thermal and micro-scale effects on various parameters during the meshing of gear in the full oil film lubrication condition, including surface pressure, oil film thickness, surface temperature, surface deformation, and friction coefficient.

A multi-perspective method for gear efficiency and contact analysis

Modern gearing applications, in particular electrification, impose new challenges in many different fields of engineering and research. In specific, new demands are imposed on gears, including higher rotational speed, lower noise acceptance, and increased efficiency, as well as increased resistance against pitting and scuffing. To meet these demands, a better understanding of gear contacts is needed. The Eurostars project Effigears proposes a novel multi-perspective methodology for assessment of gear efficiency and contact analysis. The methodology consists of using a novel surface treatment method, Triboconditioning®, implemented in a streamfinishing process, surface measurements using a scattered light method, experimental testing using the standardized FZG test rig, and contact simulations using a novel thermal elasto-hydrodynamic lubrication tool. It is found, in preliminary tests, that enhanced gear performance may be enhanced due to Triboconditioning® surface treatment. Findings also include better understanding of how surface characteristics and lubricants affect scuffing and pitting, and the effect of load distribution on gearset behavior.

Understanding the Deep Structure of the Essaouira Basin Using Gravity Data: Hydrogeological Inferences for a Semiarid Region in Central-Western Morocco

The Essaouira Basin, located in central western Morocco, faces a significant threat of water shortage due to both the substantially reduced rainfall caused by climate change and the continuously increasing demand for this essential resource. Groundwater resources are being increasingly exploited to meet the needs of the population, whether for agricultural or domestic purposes. Therefore, it has become necessary to intensify investigations across the entire basin, particularly through indirect methods such as geophysical techniques, to accurately delineate the productive zones. In this context, the present study was undertaken to investigate the deep structure of this basin with the aim of comprehending the functioning of its aquifer system. This study is based on the interpretation of gravity data covering the Essaouira Basin. In addition to their qualitative analysis, these data underwent a methodological approach involving transformations to extract meaningful insights. The observed anomalies were interpreted in terms of (i) thickness variations within the slightly folded sedimentary series of the basin; (ii) Paleozoic basement topography; and (iii) the presence of salt deposits. In fact, among the negative anomalies, some coincide with evaporitic deposits that are known either from the geological outcrops or the seismic surveys carried out in the Essaouira Basin within the framework of petroleum exploration programs, while others coincide with areas of increased thickness of sedimentary sequences. The latter include synclines and basement depressions, where the accumulation of groundwater tends to occur; as a result, they constitute suitable zones for the drilling of water extraction wells. Groundwater flows observed in some existing wells are consistent with this hypothesis. The results of the contact analysis approach implemented within the framework of the study reveals the Essaouira Basin is affected by a fault network whose main direction is parallel to the Atlantic margin (i.e., NNE–SSW). This implies that the extensional tectonic phase responsible for initiating the rifting of the Central Atlantic in the Triassic era has primarily impacted the structural configuration of this basin. This study demonstrates the strong potential of the gravity method as a tool to delineate the deep structure of sedimentary basins and to identify potentially productive groundwater zones. The final results will provide important support to decision makers in sustainable groundwater management, especially in vulnerable areas.

An individual's skin stiffness predicts their tactile discrimination of compliance.

Individual differences in tactile acuity have been correlated with age, gender and finger size, whereas the role of the skin's stiffness has been underexplored. Using an approach to image the 3-D deformation of the skin surface during contact with transparent elastic objects, we evaluate a cohort of 40 young participants, who present a diverse range of finger size, skin stiffness and fingerprint ridge breadth. The results indicate that skin stiffness generally correlates with finger size, although individuals with relatively softer skin can better discriminate compliant objects. Analysis of contact at the skin surface reveals that softer skin generates more prominent patterns of deformation, in particular greater rates of change in contact area, which correlate with higher rates of perceptual discrimination of compliance, regardless of finger size. Moreover, upon applying hyaluronic acid to soften individuals' skin, we observe immediate, marked and systematic changes in skin deformation and consequent improvements in perceptual acuity in differentiating compliance. Together, the combination of 3-D imaging of the skin surface, biomechanics measurements, multivariate regression and clustering, and psychophysical experiments show that subtle distinctions in skin stiffness modulate the mechanical signalling of touch and shape individual differences in perceptual acuity. KEY POINTS: Although declines in tactile acuity with ageing are a function of multiple factors, for younger people, the current working hypothesis has been that smaller fingers are better at informing perceptual discrimination because of a higher density of neural afferents. To decouple relative impacts on tactile acuity of skin properties of finger size, skin stiffness, and fingerprint ridge breadth, we combined 3-D imaging of skin surface deformation, biomechanical measurements, multivariate regression and clustering, and psychophysics. The results indicate that skin stiffness generally correlates with finger size, although it more robustly correlates with and predicts an individual's perceptual acuity. In particular, more elastic skin generates higher rates of deformation, which correlate with perceptual discrimination, shown most dramatically by softening each participant's skin with hyaluronic acid. In refining the current working hypothesis, we show the skin's stiffness strongly shapes the signalling of touch and modulates individual differences in perceptual acuity.

Rough surface modeling and contact analysis based on micro-scale spherical roller bearing

Rough surface modeling and contact analysis based on micro-scale spherical roller bearing

Seeking arrangements: cell contact as a cleavage-stage biomarker

Research questionWhat can three-dimensional cell contact networks tell us about the developmental potential of cleavage-stage human embryos? DesignThis pilot study was a retrospective analysis of two Embryoscope imaging datasets from two clinics. An artificial intelligence system was used to reconstruct the three-dimensional structure of embryos from 11-plane focal stacks. Networks of cell contacts were extracted from the resulting embryo three-dimensional models and each embryo's mean contacts per cell was computed. Unpaired t-tests and receiver operating characteristic curve analysis were used to statistically analyse mean cell contact outcomes. Cell contact networks from different embryos were compared with identical embryos with similar cell arrangements. ResultsAt t4, a higher mean number of contacts per cell was associated with greater rates of blastulation and blastocyst quality. No associations were found with biochemical pregnancy, live birth, miscarriage or ploidy. At t8, a higher mean number of contacts was associated with increased blastocyst quality, biochemical pregnancy and live birth. No associations were found with miscarriage or aneuploidy. Mean contacts at t4 weakly correlated with those at t8. Four-cell embryos fell into nine distinct cell arrangements; the five most common accounted for 97% of embryos. Eight-cell embryos, however, displayed a greater degree of variation with 59 distinct cell arrangements. ConclusionsEvidence is provided for the clinical relevance of cleavage-stage cell arrangement in the human preimplantation embryo beyond the four-cell stage, which may improve selection techniques for day-3 transfers. This pilot study provides a strong case for further investigation into spatial biomarkers and three-dimensional morphokinetics.

Normal contact stress analysis of large-deflection compliant mechanisms using a CPRBM-based method

The contact interaction between compliant mechanisms and external objects is a common occurrence in the field of grasping and manipulation. However, accurately modeling the large deformation and contact force/stress remains a challenging task. This paper presents a contact analysis method to evaluate the deformation and normal contact force/stress of compliant mechanisms with general-shape beams. The general beams are modeled by using the chained pseudo-rigid-body model (CPRBM). On basis of CPRBM framework, linear and distributed contact springs are introduced at the interface to represent the contact force. A numerical method is established to fast calculate the boundary penetrations, and a contact stiffness formulation is proposed based on the theory of elasticity. Then, the effect of contact interaction can be evaluated by the contact potential energy of contact springs, which is part of the system’s total potential energy. By minimizing the potential energy function of the compliant system, the static equilibrium configuration and contact force/stress can be obtained easily. Numerical examples are used to verify the feasibility and accuracy of the proposed method.

Vibration optimization of spur gear based on GSA-SA algorithm.

To determine the optimal design parameters of spur gear under a specific condition, based on the basic theories of gear dynamics theory, gear meshing principle, tooth contact analysis and load tooth contact analysis, a six-degree-of-freedom vibration analysis model of spur gear pair is established, and a gravitational search-simulated annealing hybrid algorithm (GSA-SA) is used to optimize the gear addendum modification coefficient and profile modification parameters. The vibration response of the spur gear pair is evaluated through the optimization objective function established by the combination of the G1 method and variation coefficient method. The study shows that the optimized design parameters effectively reduce the level of the vibration, which proves the effectiveness of the optimization method, and the simultaneous optimization of the addendum modification coefficient and profile modification parameters of the gear has a better result than only optimizing the addendum modification coefficient or profile modification parameters. This method can be used for gear transmission system vibration optimization design in the automotive industry and shipbuilding.

Spiral bevel gears: Bifurcation and chaos analyses of pure torsional system

The goal of this paper is to provide a detailed analysis of the complex dynamic scenario of spiral bevel gears by considering the torsional shaft stiffness. The dynamic model takes into account: time-dependent stiffness and non-smooth nonlinearity due to the backlash, i.e., teeth contact loss. The time-varying meshing stiffness is evaluated by means of a nonlinear finite element model, which allowed an accurate evaluation of the global and local teeth deformation in both directions: forward and reverse motions. Due to intentional tooth profile errors, e.g., profile modification, manufacturing error, or assembly error, the loaded and unloaded tooth contact analyses were conducted. The dynamic model was validated by comparisons with a verified SDOF model in terms of linear natural frequencies and nonlinear dynamic response. The present study provides amplitude frequency diagrams and bifurcation diagrams; for specific regimes, periodic, quasiperiodic, and chaotic responses were found. The dynamic behavior of the systems was evaluated using various tools such as modal analysis, nonlinear time series analysis, spectra, 3D-phase diagrams, and Poincaré maps. This study proves that decreasing the DOFs of the system can lose some dynamics. Different phenomena have been found such as trapping and boom-and-bust cycle. The dynamic response of different cases is evaluated by estimating the largest Lyapunov exponent and the correlation dimension. It is found that the system undergoes complex dynamic phenomena including nT-periodic, trapping, and aperiodic motions, which are evidenced in 3D-bifurcation diagrams, spectra, Poincaré maps, and 3D-phase diagrams. The chaotic motion found in this study is an undesirable behavior from a practical point of view, which can be avoided by adjusting the designed parameters. The results provide a basis for parameter design and dynamic characteristic control of the spiral bevel gear drive system.