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The purpose of this study is to evaluate the influence of the matrix system on proximal contact tightness (PCT) of posterior composite resin restorations. Standardized class II cavities on 180 first lower molar dentiform model teeth (Frasaco GmbH, Tettnang, Germany) were prepared. Three groups were formed considering the matrix system: Group-IM: Ivory matrix (Hahnenkratt GmbH, Königsbach-Stein, Germany), Group-OM: Omni matrix (Ultradent, South Jordan, UT, USA), and Group-PM: Palodent V3 sectional matrix (Dentsply, Charlotte, NC, USA). Teeth were restored with resin composite mounted in a manikin head to simulate the clinical environment. Proximal contact tightness (PCT) was measured using a custom-made portable dental pressure meter (PDPM), and the validation of the PCT results was performed with a histogram analysis acquired from bite-wing radiography. All data were statistically analyzed by ANOVA and t-test in SPSS software (v.27.0) (p < 0.05). PM group showed statistically tighter contacts on both mesial (PCTm: 228.28 ± 59.17 N) and distal surfaces (PCTd: 254.91 ± 65.69 N) (p > 0.05). Mesial contacts were found to be significantly tighter than distal contacts among all (p < 0.05). According to the histogram results, only in the PM group, the difference between the mesial and distal areas is significant (p < 0.05). Histogram results confirmed that the tightest contact values were achieved in the PM group, followed by the OM and IM groups, respectively (p < 0.05). The use of sectional matrix systems and separation rings is more effective in creating tighter contact than conventional matrix systems. The use of anatomical wedges will help to create a more natural approximal contour and narrow contact area. [ABSTRACT FROM AUTHOR]

Assuming different types of imperfect interfaces composed of a magnetoelectroelastic (MEE) structure, the current work investigates the transmission of a Love-type wave in a MEE solid cylindrical structure. The spatially variable quasi-classical technique is applied to derive the analytical solution of the layers. The substantial impact of factors related to the imperfect interface on the wave phase velocities is illustrated numerically. The Love-type wave's dispersion relation has been established as the determinant for electrically and magnetically open and short cases. Moreover, the article investigates the consequences of six different imperfect parameters namely mechanical imperfection, electrical imperfection, magnetic imperfection, magneto-mechanical imperfection, electro-mechanical imperfection, and magneto-electrical imperfection parameters in magnetically and electrically open and short scenarios are covered. The findings demonstrate that, in comparison to the short case, the electric and magnetic open case has a higher phase velocity. Here are some key findings: imperfection parameters strongly affect the phase velocity and attenuation coefficient curves and the bonding parameter's prominent influence is inversely proportional to the attenuation coefficient and well-proportional to the phase velocity. Identifying the piezoelectric and piezomagnetic connection and its possible use in the construction of sensors, actuators, energy harvesters, and nano-electronics is the result of this theoretical investigation. This is the first time that a polar coordinate system was used in the quasi-classical method of solving differential equations. The results argue that the outcomes of this specific model have an immense ability to deal with various commercial and industrial applications in acoustical engineering, geotechnical design, ultrasonic technology, and SAW devices. [ABSTRACT FROM AUTHOR]

Based on the spatial position relationship of spiral bevel gear, mathematical model and mesh model applied with finite element analysis (FEA) approach has been established. The influence of axial position errors of pinion and wheel, offset error, and shaft angle error on the meshing characteristics has been investigated. A method has been proposed to compensate the gear assembly errors by the axial displacement of the pinion and wheel, and the correctness of this method verified by numerical examples. The performed results indicate that the existence of assembly errors can cause contact pattern on the tooth surface to deviate from its design position, resulting in poor meshing quality and having a certain impact on transmission error (TE) and peak-to-peak transmission error (PPTE). The pinion and wheel's axial positioning errors can be offset by each other, whereas the offset error and shaft angle error can be mitigated by the interplay between the axial positioning of the pinion and wheel. By compensating for assembly errors with axial displacement, the position of the contact pattern can be precisely controlled, and TE will not significant changes. [ABSTRACT FROM AUTHOR]

Copyright of Lubrication Engineering (0254-0150) is the property of Editorial Office of LUBRICATION ENGINEERING and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Gears are pivotal in mechanical drives, and gear contact analysis is a typically difficult problem to solve. Emerging isogeometric analysis (IGA) methods have developed new ideas to solve this problem. In this paper, a threedimensional body parametric gear model of IGA is established, and a theoretical formula is derived to realize single-tooth contact analysis. Resultswere benchmarked against those obtained fromcommercial software utilizing the finite element analysis (FEA) method to validate the accuracy of our approach. Our findings indicate that the IGA-based contact algorithmsuccessfullymet theHertz contact test. When juxtaposed with the FEA approach, the IGAmethod demonstrated fewer node degrees of freedomand reduced computational units, all while maintaining comparable accuracy. Notably, the IGA method appeared to exhibit consistency in analysis accuracy irrespective of computational unit density, and also significantlymitigated non-physical oscillations in contact stress across the tooth width. This underscores the prowess of IGA in contact analysis. In conclusion, IGA emerges as a potent tool for addressing contact analysis challenges and holds significant promise for 3D gear modeling, simulation, and optimization of various mechanical components. [ABSTRACT FROM AUTHOR]

This study proposes a clearance, deformation, and friction numerical analysis method for cycloidal drives (CDFM) to design and optimize. The proposed method considers clearance, deformation, and friction while providing high computational efficiency for multi-parameter optimization design. Performances such as accuracy, backlash, stiffness, load capacity, and efficiency can be predicted, making this method an effective solution for optimizing cycloidal drives for high-performance robots. This study conducts simulation experiments on cycloidal drives with different parameters, and the results provide valuable insights into the effects of geometric deviations, teeth numbers, and friction coefficients on the performances of cycloidal drives. This proposed method is an efficient and effective solution for modeling and simulating cycloidal drive performance, especially transmission efficiency. It provides valuable insights into designing and optimizing cycloidal drives for high-performance robots. [ABSTRACT FROM AUTHOR]

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. • The manufacturing tolerances of standard Hirth joints were measured. • Optical and contact-based measuring machines were used. • The geometric parameters relevant for the contact were determined. • A parametric finite element model was used to simulate several contact conditions. • The influence of the manufacturing tolerances on the contact area was quantified. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Southeast University (English Edition) is the property of Journal of Southeast University Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The Hollow Cylindrical Roller Bearings (HCRBs) have some important advantages over solid cylindrical roller bearings such as low weight, good lubrication capability and high bearing stiffness. Additionally, it's also known that maximum contact stress value between the roller and race is less in hollow cylindrical roller bearings compared to solid cylindrical roller bearings. In this paper, the effect of roller's hollow size in Hollow Cylindrical Roller Bearing under a radial load on the maximum contact stress value and contact stress distribution is studied by using finite element method. The maximum tangential tensile stress occurring on the inner surface of the hollow roller is also investigated. Moreover, the effect of the penetration amount, which is a critical parameter for a nonlinear contact problem such as roller-race contact, on the contact stress is taken into consideration, as well. It's seen from the results that tangential tensile stress on the inner surface of the hollow roller has an effect on the value of optimum hollow size. Besides, it is deduced from results that the penetration amount between the contacting surfaces have considerable influence on the contact stresses and it should be taken into consideration when analyzing the roller-race contact problem by using finite element method. [ABSTRACT FROM AUTHOR]

The purpose of this study is to evaluate the influence of the matrix system on proximal contact tightness (PCT) of posterior composite resin restorations. Standardized class II cavities on 180 first lower molar dentiform model teeth (Frasaco GmbH, Tettnang, Germany) were prepared. Three groups were formed considering the matrix system: Group-IM: Ivory matrix (Hahnenkratt GmbH, Königsbach-Stein, Germany), Group-OM: Omni matrix (Ultradent, South Jordan, UT, USA), and Group-PM: Palodent V3 sectional matrix (Dentsply, Charlotte, NC, USA). Teeth were restored with resin composite mounted in a manikin head to simulate the clinical environment. Proximal contact tightness (PCT) was measured using a custom-made portable dental pressure meter (PDPM), and the validation of the PCT results was performed with a histogram analysis acquired from bite-wing radiography. All data were statistically analyzed by ANOVA and t-test in SPSS software (v.27.0) (p < 0.05). PM group showed statistically tighter contacts on both mesial (PCTm: 228.28 ± 59.17 N) and distal surfaces (PCTd: 254.91 ± 65.69 N) (p > 0.05). Mesial contacts were found to be significantly tighter than distal contacts among all (p < 0.05). According to the histogram results, only in the PM group, the difference between the mesial and distal areas is significant (p < 0.05). Histogram results confirmed that the tightest contact values were achieved in the PM group, followed by the OM and IM groups, respectively (p < 0.05). The use of sectional matrix systems and separation rings is more effective in creating tighter contact than conventional matrix systems. The use of anatomical wedges will help to create a more natural approximal contour and narrow contact area.

This study examines the effects of macroscopic bending and microscopic contact loading in inhomogeneous materials using a semi-analytical model based on Eshelby's equivalent inclusion method. The model accounts for bending effects through the beam theory, with bending stress included in the Eshelby's equivalent inclusion equations. The macroscopic displacement resulting from bending effects is incorporated into the microscopic contact solver, and the final displacement is determined using the conjugate gradient method in an iterative solution. Computational efficiency can be improved by incorporating the discrete convolution and fast Fourier transform. The core scheme is validated using the finite element method, yielding accurate and efficient results for bending-contact problems in inhomogeneous materials. Simulations reveal the interplay between bending, contact loading, and inhomogeneity, as stress around the inhomogeneity alters and the stress concentration area expands under increasing bending moments. Conversely, low-magnitude negative bending moments reduce both contact pressure and stress around the inhomogeneity. The position where inhomogeneities are least affected shifts from the neutral surface depending on the coupling effect. The model provides a valuable bridge for connecting the macroscopic bending effect and microscale contact-inhomogeneity problems by visualizing stress fields and assessing pressure distributions. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Loaded tooth contact analysis (LTCA) adopted to obtain the static transmission error for the gear optimization affects significantly the computation time and results. This paper is to study an efficient process of macro geometry optimization of helical gear pairs with LTCA. An analytical LTCA model was proposed and verified with the measured transmission error. To find an efficient LTCA method, the proposed model was divided into three types (based on whether the slice stiffness and extended contact were included) by adjusting the fidelity. When extended contact was included in LTCA, the increased computation time was very short, but the accuracy of the results improved significantly. Optimization processes were designed based on the analysis results, and it was most efficient when starting with the model considering only the extended contact and ending 5%−10% of the entire generation with the highest fidelity model. In the process, the computational effort was significantly reduced compared to when the optimization process was configured with only the highest fidelity model, and the level of optimization was almost equal. [ABSTRACT FROM AUTHOR]

Copyright of China Mechanical Engineering is the property of Editorial Board of China Mechanical Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Involute tooth profile contains a lot of waviness information. Digging and expanding the application of waviness information to establish its relationship with gear transmission performance has important engineering value. Studying the construction principle of equation of the involute with waviness is to fit the waviness curve based on the measured teeth surfaces data. The involute tooth profiles with different sine waviness are constructed. Based on the meshing principle, the correlation of wavelength, amplitude, phase of waviness and transmission error is analyzed in the time domain and frequency domain, and verified by actual tooth surface data. The finite element model of involute tooth surface with waviness is established, and the correlation between wavelength, amplitude, phase of waviness and contact stress in gear transmission is simulated and analyzed. The gear transmission error test is carried out to verify the correctness of the calculation of transmission error. The results show that the fluctuation amplitude of transmission error is sensitive to the amplitude change of tooth profile waviness; the periodicity of tooth profile waviness is related to the order component of transmission error; with the increase of the number of waviness fluctuation periods, the order amplitude of the corresponding multiple of the number of teeth increases significantly; the magnitude of tooth surface contact stress is mainly affected by the amplitude of profile waviness. Thus the waviness information of gear measurement results between macro and micro quantities is extended and applied, and the research provides a basis for predicting transmission performance based on waviness information.

Six meta-substituted isophthalamide diesters (DxE) and pyridinedicarboxamides (PxE) are reported with spectroscopic and crystal structure analyses (D = meta-C6H4; P = meta-pyridine; xE = 2-/3-/4-ethyl ester substitution). Comparisons are made between the solid-state and minimised structures from ab initio computational calculations. The six compounds are potentially useful ligands for metal-complex coordination, spanning a range of molecular conformations. D2E adopts a planar molecular structure, as influenced by the C-H⋯O intramolecular interactions with all 34 nonhydrogen atoms within 0.1 Å of the D2E mean molecular plane. Extensive intermolecular ring⋯ring stacking arises with the shortest interplanar C⋯C of 3.372(2) Å. For D3E (Z′ = 4) and D4E, the hierarchy of intermolecular interactions is the determining factor driving the crystal structure formation with concomitant twinning, as influenced by the weaker interactions. In the pyridine-related P2E, the O1W water molecule (site occupancy = 0.441(5)) forms four hydrogen bonds, as follows: (i) O1W−H⋯O=C, (ii) O1W−H⋯π(arene) and (iii) two aromaticC−H⋯O1W. The meta- and para-substituted PxE·2(H2O) structures (x = 3 or 4) adopt open conformations with pairs of hydrogen-bonded water molecules located in molecular niches between the flanking benzamide ester groups. The Hirshfeld surface, two-dimensional fingerprint plots and contact enrichment ratio were investigated to statistically analyse the different types of intermolecular interactions. [ABSTRACT FROM AUTHOR]

With the development of high-pressure, high-temperature wells, the sealability of premium connections is being threatened by heavy loads. For the sake of researching the sealability of premium connections at the microlevel on the sealing surface, a rough profile was characterized according to a fractal function, and the influence of the fractal parameters of contact behavior on the rough surface was analyzed. A full-size premium connection model with a fractal surface FEM was established using ABAQUS software to analyze the Von Mises stress and contact pressure, and the sealability was then analyzed using contact strength theory. It was found that utilizing fractal functions to describe the rough morphology on the sealing surface of premium connections could reveal the contact behavior of the sealing surface more realistically. The premium connection's fractal FEM was closer to the actual situation, considering the effect of the asperities' elastic–plastic deformation on the sealability. The fractal dimension D had a greater influence on the contact area and contact pressure than the scale coefficient G. When the fractal dimension D was less than 2.5, the maximum Von Mises stress and maximum contact pressure on the sealing surface were 8.81 × 108 Pa and 1.20 × 109 Pa, respectively, making the surface prone to gluing. The sealability of the premium connection was primarily affected by the axial tension. When the axial tension was 1.2 × 106 N, the sealing surface experienced significant displacement along the axial direction, the effective contact length reduced from 2.72 × 10−3 m to 2.24 × 10−3 m, and the maximum contact pressure reduced from 8.10 × 108 Pa to 6.39 × 108 Pa, which led to a 30% decrease in sealing strength, which may pose a high risk of sealing failure. When the internal pressure reached 1 × 108 Pa, the effective contact length increased from 9.08 × 10−3 m to 1.06 × 10−2 m, the maximum contact pressure increased from 8.67 × 108 Pa to 1.37 × 109 Pa, and the sealing strength increased by 23%. [ABSTRACT FROM AUTHOR]

Copyright of Machine Tool & Hydraulics is the property of Guangzhou Mechanical Engineering Research Institute (GMERI) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Empirical joint contact mechanics measurement (EJCM; e.g. contact area or force, surface velocities) enables critical investigations of the relationship between changing joint mechanics and the impact on surface-to-surface interactions. In orthopedic biomechanics, understanding the changes to cartilage contact mechanics following joint pathology or aging is critical due to its suggested role in the increased risk of osteoarthritis (OA), which might be due to changed kinematics and kinetics that alter the contact patterns within a joint. This article reviews and discusses EJCM approaches that have been applied to articulating joints such that readers across different disciplines will be informed of the various measurement and analysis techniques used in this field. The approaches reviewed include classical measurement approaches (radiographic and sectioning, dye staining, casting, surface proximity, and pressure measurement), stereophotogrammetry/motion analysis, computed tomography (CT), magnetic resonance imaging (MRI), and high-speed videoradiography. Perspectives on approaches to advance this field of EJCM are provided, including the value of considering relative velocity in joints, tractional stress, quantification of joint contact area shape, consideration of normalization techniques, net response (superposition) of multiple input variables, and establishing linkages to regional cartilage health status. EJCM measures continue to provide insights to advance our understanding of cartilage health and degeneration and provide avenues to assess the efficacy and guide future directions of developing interventions (e.g. surgical, biological, rehabilitative) to optimize joint's health and function long term. [ABSTRACT FROM AUTHOR]

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.

Manufacturing errors are one of the main causes of vibration and noise of gear transmission system，and the combination of multiple errors seriously affects the meshing performance of gear pairs. The influence degree and law of various manufacturing errors on meshing performance of herringbone gear pairs are mainly studied. Firstly，the manufacturing error model is established，and the actual tooth surface is constructed based on the theory of spatial coordinate transformation. Secondly，the influence law of different errors on the meshing performance of the gear pair is explored through the load distribution on the tooth surface，and the influence degree of different errors is explored based on the orthogonal experiment. Finally，the relationship between the influence of typical error types on the meshing performance of gear pairs and the system load is analyzed. The results show that the influence law of various errors on the meshing performance of gear pair is different，and the positive tilt deviation of helix direction has the most prominent influence on the meshing performance of gear pairs under heavy load.

The cable net and membrane of the air-supported membrane structure transmits the load through mutual extrusion, and the contact interaction between the cable net and membrane should be considered in the initial morphological analysis stage. In this paper, a scale model was designed according to a large-span air-supported membrane structure engineering project, and the shape and force of the structure were measured. At the same time, a finite element model of cable–membrane contact was established, and its interaction behavior was regarded as a combined contact state and sliding contact state. The results show that the influence of different contact state analyses on the prestress of the cable net is obvious, and the influence of the sliding contact between the cable and the membrane should be considered in the design of the membrane structure. [ABSTRACT FROM AUTHOR]

Bu çalışmada çift pim bağlantısı uygulanmış ve epoksi yapıştırıcı ile yapıştırılmış cam fiber/epoksi tabakalı kompozit plakada farklı delik eksen pozisyonları için oluşan gerilmeler belirlenmiş ve karşılaştırılmıştır. Analiz, modelleme ve çözüm için ANSYS (V19) sonlu elemanlar yazılımı kullanılmıştır. Modelleme üç boyutlu olarak yapılmıştır. Model üzerine gerekli sınır şartları ve yüklemeler uygulanmıştır. Mevcut çalışmalardan farklı olarak, tabakalı kompozit plaka üzerindeki delik ve pim için kontak analizi yapılmış ve analiz bu şekilde gerçekleştirilmiştir. Malzemeye çekme yükü uygulanarak, delik eksenlerinin kenara ve delik eksenleri arası mesafe oranları için modeller arasında meydana gelen gerilmeler belirlenmiş ve karşılaştırılmıştır. Çalışmada delik ekseninin kenara uzaklığının çapa oranı (E/D) 5, 4, 3, 2 seçilmiş ve delik eksenleri arası uzaklığın çapa oranı da (K/D) 5, 4, 3, 2 seçilmiştir. Çalışmanın sonuçlarında yapıştırıcı tabakasındaki gerilmeler delik eksenlerindeki değişimlerden yüksek oranda etkilenmediği görülmüştür. Kenara yakın delikteki aynı K/D değerleri için E/D değerlerindeki azalma, basma gerilmelerinde artışa neden olmuştur. Kenardan uzaktaki delikte ise aynı K/D değerleri için E/D değerlerindeki azalma ile çekme gerilmelerinde azalma görülmüştür.

This study combines geochemical anomaly separation with geostatistical approaches and compositional data analysis. To have a reasonable model for abnormal areas, suggesting the optimal drilling coordinates, one needs to consider some effective geological controllers on the mineralization such as lithology, alteration, and tectonic processes. The lithogeochemical samples at 608 locations were processed from the copper porphyry mineralization area of Kuh Panj, Iran, to illustrate the proposed approach. The heterogeneity of rock type domains was detected using contact analysis. Based on this, plurigaussian simulation made it possible to model the uneconomic dykes of the area. Copper-molybdenum grades and filler as geochemical components were transformed into multivariate normal data using isometric logarithmic ratio-flow anamorphosis. Hierarchical rock type-grade simulation reproduced the grade behavior at hard rock type boundaries. Selection of a dense and regular simulation grid minimized the smoothing effect caused by interpolation of the singularity index values. Finally, unsupervised machine learning identified the anomaly zone by clustering the results of the singularity analysis. Validation using drilling data and the geological map shows that the anomaly separation, considering the geological conditions and the compositional nature of the geochemical data, can provide a reliable model of the geochemical anomalies in the Kuh Panj deposit. • A multivariate approach is proposed for anomaly separation on lithogeochemical data. • Compositional data and contact analyses, singularity mapping and K-means were combined. • Borehole data proved that the proposed approach effectively identifies the anomaly zone. [ABSTRACT FROM AUTHOR]

The load of ball cage type constant velocity joint of military off-road vehicle is larger than that of traditional vehicle, and the working condition is bad, which may cause contact wear, as well as the fracture of the cage under the angle between large axes. Therefore, it is very important to study the contact stress and the strength of the cage under the bad working condition. In this paper, a typical military off-road vehicle ball cage constant velocity joint is taken as the object. Firstly, the contact stress between the steel ball and the inside and outside raceway is theoretically analyzed and simulated. The simulation and analytical results are compared to verify the correctness of the simulation model. Secondly, according to the load transfer relationship between the key parts of the universal joint and the physical experiment, the reason and process of cage fracture are analyzed. Finally, the static torsion test under the ultimate axial angle is carried out, and the hardness test is carried out on the section of the cage. The strength distribution along the thickness is obtained through the relationship between hardness and strength conversion. The results show that the strength of the cage meets the requirements under normal working conditions, but may be broken under bad working conditions. This research can provide theoretical reference for the design and manufacture of constant velocity joint for off-road vehicle.

The discrete element method is widely used to analyze the dynamic behavior of a wheel driving on the sandy road. The tetra clustering model for generating arbitrary shape of a particle is developed. A contact method between a wheel and numerous particles is developed to carry out simulation. A wheel testbed experimental setup is established for investigating the contact phenomenon between a wheel and sand particles. A high-speed camera is used for capturing the motion of the wheel. The technique for solving multibody dynamics and particle dynamics simultaneously is suggested. The repose angle test is carried out to obtain the contact parameter between particles. The static equilibrium test of a wheel is performed to obtain the contact parameter between a wheel and particle. The dynamic motion of the wheel according to the slip ratio is compared with experiments. According to results, simulation results show a good agreement with experiments. [ABSTRACT FROM AUTHOR]

Due to the complex manufacturing process and numerous machine-tool settings, errors easily arise between the actual parameters and theoretical parameters of spiral bevel gear, which contributes to the deviation of geometrical morphology of gear flank. This type of gear pair is very sensitive to tooth flank deviations, and the deviations can affect the mesh behavior of the gear pair and then the performance of the entire device. To investigate the influence of different machine-tool setting errors on the mesh behavior of small-module spiral bevel gear, a mathematical model of this type of gear pair has been established based on the principle of duplex spread blade method, and the finite element analysis model has been developed under the rated condition. The horizontals and radial distances of pinion and wheel as well as the velocity ratio were selected to be investigated. The three machine-tool setting all makes the contact pattern move within the tooth flank. The minimum value of transmission error (TE) appears at the initial horizontal and radial distance. Negative values of the horizontal and radial distance and positive value of velocity ratio both can increase the root bending stress. The errors of machine-tool setting will increase the tooth contact stress. The main influential errors on mesh behavior of small-module spiral bevel gear are in proper order, horizontal, radial distance and velocity ratio. It is convenient and efficient to correct the tooth flanks in this order only by contrasting the contact pattern with the design after the rolling test. [ABSTRACT FROM AUTHOR]

With the growing interest in 3D printing, many studies are being conducted to replace conventional manufacturing processes. In terms of mechanical applications, however, research on the tribological characteristics of 3D printing components has not been sufficiently conducted. This study investigated the influences of surface texturing and roughness on 3D printed specimens. Specimens with and without surface texture were printed using a 3D printer, and their frictional behavior was compared. The friction coefficient of the textured specimen was smaller than that of the untextured specimen. Contact analysis was conducted to evaluate the mechanism. The analysis suggested that the real contact area of the untextured specimen was similar to that of the textured specimen during the initial stage. However, the wear of asperities during the friction test increased the real contact area of the untextured specimen. Surface roughness was verified to influence the untextured specimen more significantly than the textured specimen in terms of tribological behavior. [ABSTRACT FROM AUTHOR]

This paper presents the node-based smoothed finite element method with linear strain functions (NS-FEM-L) for solving contact problems using triangular elements. The smoothed strains are formulated by a complete order of polynomial functions and normalized with reference to the central points of smoothing domains. They are one order higher than those adopted in the finite element method (FEM) and the standard smoothed finite element method with the same triangular mesh. When using linear functions to describe strains in smoothing domains, the solutions are more accurate and stable. The contact interfaces are discretized by contact point pairs using a modified Coulomb frictional contact model. The contact problems are solved via converting into linear complementarity problems (LCPs) which can be tackled by using the Lemke method. Numerical implementations are conducted to simulate the contact behavior, including the bonding–debonding, contacting–departing and sticking–slipping. The effects of various parameters related to friction and adhesion are intensively investigated. The comparison of numerical results produced by different methods demonstrates the validity and efficiency of the NS-FEM-L for contact problems. [ABSTRACT FROM AUTHOR]

This paper presents a cell-based smoothed finite element method (CS-FEM) for solving two-dimensional contact problems with the bi-potential formulation. The contact force and the relative displacements on the contact surface are coupled with each other. The Uzawa algorithm, which is a local iterative technique, is used to solve the contact force. The classic Coulomb friction rule and a unilateral contact relationship are considered. There is no need to select any user-defined parameter in the whole process. Three contact states are investigated accurately, which can be stated as sticking, separating and sliding, respectively. The CS-FEM is performed with six different kinds of smoothing domains which are constructed by dividing the background element into different regions. Only boundary integrations instead of domain integral are required in the calculation, and no coordinate mapping is needed. Three numerical examples are presented to verify the effectiveness of the method. The effect of the friction coefficient for the contact is also investigated. All the obtained numerical solutions agree well with the reference values. The results produced by the CS-FEM are more accurate than those of the traditional FEM. Moreover, the CS-FEM can provide both an upper bound and a lower bound of the strain energy solutions while using different smoothing domains. [ABSTRACT FROM AUTHOR]

Six meta-substituted isophthalamide diesters (DxE) and pyridinedicarboxamides (PxE) are reported with spectroscopic and crystal structure analyses (D = meta-C6H4; P = meta-pyridine; xE = 2-/3-/4-ethyl ester substitution). Comparisons are made between the solid-state and minimised structures from ab initio computational calculations. The six compounds are potentially useful ligands for metal-complex coordination, spanning a range of molecular conformations. D2E adopts a planar molecular structure, as influenced by the C-H⋯O intramolecular interactions with all 34 nonhydrogen atoms within 0.1 Å of the D2E mean molecular plane. Extensive intermolecular ring⋯ring stacking arises with the shortest interplanar C⋯C of 3.372(2) Å. For D3E (Z′ = 4) and D4E, the hierarchy of intermolecular interactions is the determining factor driving the crystal structure formation with concomitant twinning, as influenced by the weaker interactions. In the pyridine-related P2E, the O1W water molecule (site occupancy = 0.441(5)) forms four hydrogen bonds, as follows: (i) O1W−H⋯O=C, (ii) O1W−H⋯π(arene) and (iii) two aromaticC−H⋯O1W. The meta- and para-substituted PxE·2(H2O) structures (x = 3 or 4) adopt open conformations with pairs of hydrogen-bonded water molecules located in molecular niches between the flanking benzamide ester groups. The Hirshfeld surface, two-dimensional fingerprint plots and contact enrichment ratio were investigated to statistically analyse the different types of intermolecular interactions.

With the development of high-pressure, high-temperature wells, the sealability of premium connections is being threatened by heavy loads. For the sake of researching the sealability of premium connections at the microlevel on the sealing surface, a rough profile was characterized according to a fractal function, and the influence of the fractal parameters of contact behavior on the rough surface was analyzed. A full-size premium connection model with a fractal surface FEM was established using ABAQUS software to analyze the Von Mises stress and contact pressure, and the sealability was then analyzed using contact strength theory. It was found that utilizing fractal functions to describe the rough morphology on the sealing surface of premium connections could reveal the contact behavior of the sealing surface more realistically. The premium connection’s fractal FEM was closer to the actual situation, considering the effect of the asperities’ elastic–plastic deformation on the sealability. The fractal dimension D had a greater influence on the contact area and contact pressure than the scale coefficient G. When the fractal dimension D was less than 2.5, the maximum Von Mises stress and maximum contact pressure on the sealing surface were 8.81 × 108 Pa and 1.20 × 109 Pa, respectively, making the surface prone to gluing. The sealability of the premium connection was primarily affected by the axial tension. When the axial tension was 1.2 × 106 N, the sealing surface experienced significant displacement along the axial direction, the effective contact length reduced from 2.72 × 10−3 m to 2.24 × 10−3 m, and the maximum contact pressure reduced from 8.10 × 108 Pa to 6.39 × 108 Pa, which led to a 30% decrease in sealing strength, which may pose a high risk of sealing failure. When the internal pressure reached 1 × 108 Pa, the effective contact length increased from 9.08 × 10−3 m to 1.06 × 10−2 m, the maximum contact pressure increased from 8.67 × 108 Pa to 1.37 × 109 Pa, and the sealing strength increased by 23%.

The simulation of the comminution process of a lithium-ion battery model and evaluation of the performance of three cylindrical battery models derived from previous studies were achieved in the present study. The finite element method (FEM) was used along with dynamic simulation procedures. The models were classified based on the battery material model parameters used in the analysis, namely type A, B, and C models. The battery material models of type A and C were unable to provide results that were consistent with real-world circumstances. In contrast, the type B model gives a realistic battery dynamic reaction. Additional testing on the type B model was performed in terms of battery shard size, fracture energy, comminution pressures, element displacement, battery element velocity, and device capacity calculation. The simulation results revealed that the type B model in this study is capable of properly predicting the dynamic response of the battery, notably when compared to the other two models. The study in the present research could be used in the future to identify the proper cutting tool geometry, estimate the size of the comminution product, and play an important role in the design and optimization of the comminution machine. [ABSTRACT FROM AUTHOR]

The multitooth meshing state of harmonic drive (HD) is an important basic characteristic of its high transformation precision and high bearing capacity. Meshing force distribution affects the load sharing of the tooth during meshing, and theoretical research remains insufficient at present. To calculate the spatial distributed meshing forces and loading backlashes along the axial direction, an iterative algorithm and finite element model (FEM) is proposed to investigate the meshing state under varied transmission loading. The displacement formulae of meshing point under tangential force are derived according to the torsion of the flexspline cylinder and the bending of the tooth. Based on the relationship of meshing forces and circumferential displacements, meshing forces and loading backlashes in three cross-sections are calculated with the algorithm under gradually increased rotation angles of circular spline, and the results are compared with FEM. Owing to the taper deformation of the cup-shaped flexspline, the smallest initial backlash and the earliest meshing point appear in the front cross-section far from the cup bottom, and then the teeth in the middle cross-section of the tooth rim enter the meshing and carry most of the loading. Theoretical and numerical research show that the flexibility is quite different for varied meshing points and tangential force amplitude because of the change of contact status between the flexspline and the wave generator. The meshing forces and torsional stiffness of the HD are nonlinear with the torsional angle. [ABSTRACT FROM AUTHOR]

When spur gear pair meshing with the assembly error，it will cause the edge contact and stress concentration，and affect the service life. In the meantime，because the parallelism error of vertical plane will produce a larger deviation of tooth contact，therefore，taking the spur gear pair with the parallelism error of vertical plane as the research object，then based on the systematic introduction of the numerical calculation theory of gear contact stress，and the contact stress，contact width and the corresponding load distribution coefficient along the tooth in the case of different assembly error and load conditions are calculated，and the results calculated by numerical calculation method and national standard calculation method in the case of no assembly error are made a comparative analysis. The results show that the results calculated by two methods in the case of no assembly error are close to each other，and the numerical calculation result can reflect the edge effect of the gear pair meshing. Under the same load，with the increase of the installation error，the uneven contact in the tooth width direction becomes worse，and one side disconnects. Under the same assembly error，the uneven contact is improved with the increase of load，the maximum contact stress presents nonlinear increase with the increase of assembly error and load.

Thanks to the development and application of coating technology and polymer rotor material, it is an inevitable trend to eliminate synchronous gear for water-injected and dry twin-screw compressors, especially running at a high speed, due to much power consumed by synchronous gears. However, it is not economical and reliable to rely only on coating or rotor material to enhance the wear resistance of rotor. This paper attempts to lighten the rotor wear in twin-screw compressors from the angle of setting driving belt. To achieve this goal, the contact analysis is carried out in this paper, taking the rotor profile of a developed water-lubricated twin-screw air compressor as an example. By the contact analysis, equivalent curvature radius, Hertz contact stress, sliding distance, the value of P H S, and the minimum film thickness of each mesh point on different tooth curve are calculated and discussed. The product of the Hertz contact stress and total sliding distance, P H S, and minimum film thickness are chosen as the evaluation indexes to estimate the wear resistance of all tooth curves. By comparing these indexes of each tooth curve, some suggestions about setting the driving belt are proposed. [ABSTRACT FROM AUTHOR]

Purpose: A new CR TKA design with concave medial and convex lateral tibial polyethylene bearing components was introduced recently to improve functional outcomes. This study aimed to investigate in-vivo articular contact kinematics in unilateral asymmetrical tibial polyethylene geometry CR TKA patients during strenuous knee flexion activities. Methods: Fifteen unilateral CR TKA patients (68.4 ± 5.8 years; 6 male/9 female) were evaluated for both knees during sit-to-stand, single-leg deep lunges and step-ups using validated combined computer tomography and dual fluoroscopic imaging system. Medial and lateral condylar contact positions were quantified during weight-bearing flexion activities. The Wilcoxon signed-rank test was performed to determine if there is a significant difference in articular contact kinematics during strenuous flexion activities between CR TKA and the non-operated knees. Results: Contact excursions of the lateral condyle in CR TKAs were significantly more anteriorly located than the contralateral non-operated knee during sit-to-stand (3.7 ± 4.8 mm vs − 7.8 ± 4.3 mm) and step-ups (− 1.5 ± 3.2 mm vs − 6.3 ± 5.8 mm). Contact excursions of the lateral condyle in CR TKAs were significantly less laterally located than the contralateral non-operated knee during sit-to-stand (21.4 ± 2.8 mm vs 24.5 ± 4.7 mm) and single-leg deep lunges (22.6 ± 4.4 mm vs 26.2 ± 5.7 mm, p < 0.05). Lateral condyle posterior rollback was not fully restored in CR TKA patients during sit-to-stand (9.8 ± 6.7 mm vs 12.9 ± 8.3 mm) and step-ups (8.1 ± 4.8 mm vs 12.2 ± 6.4 mm). Lateral pivoting patterns were observed in 80%, 73% and 69% of patients during sit-to-stand, step-ups and single-leg deep lunges respectively. Conclusion: Although lateral femoral rollback and lateral pivoting patterns were observed during strenuous functional daily activities, asymmetric contact kinematics still persisted in unilateral CR TKA patients. This suggests the specific investigated contemporary asymmetrical tibial polyethylene geometry CR TKA design evaluated in this study does not fully replicate healthy knee contact kinematics during strenuous functional daily activities. Level of evidence: III. [ABSTRACT FROM AUTHOR]

The contact calculation of three-dimensional real rough surfaces is the frontier field of tribology and surface science. In this study, we consider the interaction and elastic-plastic deformation characteristics of asperities and further, propose an analytical contact calculation method for rough surfaces considering the interaction of asperities. Based on the watershed algorithm, the rough surface is segmented and the asperities are reconstructed into ellipsoids. According to the height relationship between the asperities, the definition of the deformation reference height of the matrix between each couple of asperities is provided. Subsequently, the calculation formula of the substrate deformation is provided according to the local contact pressure considering the elastic-plastic deformation of the asperity, and the contact state under a specific load is determined using the iterative correction method. The results correspond with those of finite element numerical calculation and the study reveals the following: (1) compared with the results obtained without considering the asperity interaction, contact area, distance, and stiffness will be reduced by 6.6%, 19.6%, and 49.5%, respectively, when the influence of asperity interaction is considered; (2) the interaction of the asperities has the greatest influence on the surface contact distance and stiffness. Under the same load, the existence of asperity interaction will reduce the contact distance, area, and stiffness; (3) considering the interaction of the asperities, the higher asperity will bear more load, but it will simultaneously reduce the contact of the surrounding area and increase that of the distant area. The calculation method proposed in this study has the advantages of high calculation efficiency and accuracy, thus, providing the calculation basis and method for subsequent studies on service performance of rough surfaces, such as the calculation of contact stiffness and fatigue performance analysis of rough surfaces. [ABSTRACT FROM AUTHOR]

In order to study the meshing stiffness of variable hyperbolic arc gear， the tooth surface equation of variable hyperbolic arc gear is obtained according to the forming principle， and its accurate three-dimensional model is established. Based on the theory of contact finite element analysis， the calculation method of meshing stiffness is studied. Using the finite element software， a pair of gear finite element model is constructed. The comprehensive elastic deformation of the tooth surface is extracted， and the normal contact force of the tooth surface is calculated by the torque formula. The single tooth mesh stiffness and the double tooth comprehensive mesh stiffness are calculated， which the results show that the stiffness curve of single tooth mesh increases first and then decreases with the increase of driving wheel angle. Then， the influence of different loads on the meshing stiffness curve is analyzed. The results show that the peak value of the stiffness curve increases with the increase of the load， and the load has more obvious influence on the peak value of the comprehensive meshing stiffness curve of the double teeth. At last， the influence of different tooth radius on the meshing stiffness curve is analyzed. The results reveal that the peak stiffness curve decreases with the increase of tooth radius， and the stiffness difference between the meshing area of single and double teeth decreases.

Based on the tooth surface equation of the Variable hyperbolic circular-arc-tooth-trace （VH-CATT）， the gear meshing principle is used to analyze the tooth surface contact during the meshing process， the positions distribution of the VH-CATT meshing point during meshing process of the concave and convex tooth surface is obtained. According to the principles of gear geometry， the formulas for calculating the important parameters of EHL such as the principal curvatures and entrainment velocity of the VH-CATT meshing point during meshing process of the concave and convex tooth surface is obtained. The Downson-Higginson minimum film thickness model is used to analyze the minimum film thickness of EHL in the VH-CATT meshing process， and the variation rules of EHL minimum film thickness in the meshing process of gear pairs with different gear design parameters are obtained. Theoretical analysis shows that the lubrication condition between the dedendum of driver gear （the concave tooth surface） and the addendum of driven gear （the convex tooth surface） of VH-CATT is the worst， where the wear failure of tooth surface is most likely to occur. When the input load increases， the minimum film thickness decreases slightly， and the gear is provided with the characteristics of impact load resistance. With the increase of pressure angle， the minimum film thickness increases so that the lubricity and bearing capacity are improved. When the tooth trace radius becomes longer， the minimum film thickness decreases slightly， selecting a reasonable cutter head radius to process the gear can improve the lubricity. The results provide a theoretical basis for the lubrication design and wear calculation of VH-CATT.

Finite element contact analysis of a planetary drive with small teeth difference in a beveloid gear RV drive was carried out. The results show that the meshing performance differs from that of the traditional gear design theory result. The effect of elastic meshing under different loads on the axial force,contact force,number of actual contact teeth,load distribution among the teeth,contact stress of the tooth surface and tooth root stress. The results of the analysis provide the basis for improving the bearing capacity,gear parameter optimization,tooth profile modification and the strength calculation of parts with small teeth difference.