Готові списки джерел за темами / Non-Hertzian

Добірка наукової літератури з теми "Non-Hertzian"

Автор: Grafiati

Опубліковано: 14 березня 2023

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Статті в журналах з теми "Non-Hertzian"

Sun, Tiewei, Min Wang, Xiangsheng Gao, and Yingjie Zhao. "Non-Hertzian Elastohydrodynamic Contact Stress Calculation of High-Speed Ball Screws." Applied Sciences 11, no. 24 (December 18, 2021): 12081. http://dx.doi.org/10.3390/app112412081.

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In order to eliminate the calculation error of the Hertzian elastohydrodynamic contact stress due to the asymmetry of the contact region of the helix raceway, a non-Hertzian elastohydrodynamic contact stress calculation method based on the minimum excess principle was proposed. Firstly, the normal contact stresses of the screw raceway and the nut raceway were calculated by the Hertzian contact theory and the minimum excess principle, respectively. Subsequently, the Hertzian solution and the non-Hertzian solution of the elastohydrodynamic contact stress could be determined by the Reynolds equation under different helix angles and screw speeds. Finally, the friction torque test of the double-nut ball screws was designed and implemented on a self-designed bed for validation of the proposed method. The comparison showed that the experimental friction torque was the good agreement with the simulated friction torque, which verified the effectiveness and correctness of the non-Hertzian elastohydrodynamic contact stress calculation method. Under the large helix angle, the calculation accuracy of asperity contact stress for the non-Hertzian solution was more accurate than that of the Hertzian solution at the contact region of ball screws. Therefore, the non-Hertzian elastohydrodynamic contact stress considering the asymmetry of the raceway contact region could more accurately analyze the wear depth of the high-speed ball screws.

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Hanson, M. T., L. M. Keer, and T. N. Farris. "Energy Dissipation in Non-Hertzian Fretting Contact." Tribology Transactions 32, no. 2 (January 1989): 147–54. http://dx.doi.org/10.1080/10402008908981873.

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Askari, Ehsan. "Mathematical models for characterizing non-Hertzian contacts." Applied Mathematical Modelling 90 (February 2021): 432–47. http://dx.doi.org/10.1016/j.apm.2020.08.048.

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Hooke, C. J. "A Note on the Elastohydrodynamic Lubrication of Soft Contacts." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 200, no. 3 (May 1986): 189–94. http://dx.doi.org/10.1243/pime_proc_1986_200_114_02.

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The clearances in highly loaded non-Hertzian contacts can be calculated directly from the dry contact pressure distribution. This note presents a method of extending the analysis into less highly loaded regions. It is shown that the method accurately predicts the clearance over much of the transition zone for Hertzian contacts and its use in a non-Hertzian situation is illustrated using the contact between a rigid cylinder and an elastomer-lined surface as an example.

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Sackfield, A., and D. A. Hills. "The Strength of Some Non-Hertzian Plane Contacts." Journal of Tribology 108, no. 4 (October 1, 1986): 655–58. http://dx.doi.org/10.1115/1.3261296.

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The problem of plane elastic contact between a symmetrical indentor and a half-plane is addressed. The form of the contacting profile of the indentor is represented in terms of Chebyshev polynomials, and the resulting stress-field is deduced, for both static and sliding contact. It is shown that by making the profile somewhat flatter than a cylinder a large load may be sustained without yielding. Practical implications of the result, including profiles needed to attain optimal contact conditions, are discussed.

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Ouyang, Wenze, Bin Sun, Zhiwei Sun, and Shenghua Xu. "Anomalous and non-Gaussian diffusion in Hertzian spheres." Physica A: Statistical Mechanics and its Applications 505 (September 2018): 61–68. http://dx.doi.org/10.1016/j.physa.2018.03.034.

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Liu, C., and B. Paul. "Rolling Contact With Friction and Non-Hertzian Pressure Distribution." Journal of Applied Mechanics 56, no. 4 (December 1, 1989): 814–20. http://dx.doi.org/10.1115/1.3176176.

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A numerical technique has been developed to deal with three-dimensional rolling contact problems with an arbitrary contact region under an arbitrary pressure. Results of this technique are checked against existing solutions for cases of Hertzian contact. A solution for a case of non-Hertzian contact is also presented. This numerical technique works satisfactorily for cases with small spin creepage. For cases of large spin creepage, we utilize a recent work (by the authors) for the limiting case of fully developed sliding contact.

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An, Boyang, Daolin Ma, Ping Wang, Jiayi Zhou, Rong Chen, Jingmang Xu, and Dabin Cui. "Assessing the fast non-Hertzian methods based on the simulation of wheel–rail rolling contact and wear distribution." Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit 234, no. 5 (May 9, 2019): 524–37. http://dx.doi.org/10.1177/0954409719848592.

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This paper aims at assessing several fast non-Hertzian methods, coupled with two wear models, based on the wheel–rail rolling contact and wear prediction. Four contact models, namely Kik-Piotrowski's method, Linder's method, Ayasse-Chollet's STRIPES algorithm and Sichani's ANALYN algorithm are employed for comparing the normal contact. For their tangential modelling, two tangential algorithms, i.e. FASTSIM and FaStrip, are used. Two commonly used wear models, namely the Archard (extended at the KTH Royal Institute of Technology) and USFD (developed by the University of Sheffield based on T-gamma approach), are further utilized for wear distribution computation. All results predicted by the fast non-Hertzian methods are evaluated against the results of Kalker's CONTACT code using penetration as the input. Since the two wear models adopt different expressions for calculating the wear performance, the attention of this paper is on assessing which one is more suitable for the fast non-Hertzian methods to utilize. The comparison shows that the combination of the USFD wear model with any of the fast non-Hertzian methods agrees better with CONTACT+USFD. In general, ANALYN+FaStrip is the best solution for the simulation of the wheel–rail rolling contact, while STRIPES+FASTSIM can provide better accuracy for the maximum wear depth prediction using the USFD wear model.

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Ciulli, Enrico, Alberto Betti, and Paola Forte. "The Applicability of the Hertzian Formulas to Point Contacts of Spheres and Spherical Caps." Lubricants 10, no. 10 (September 23, 2022): 233. http://dx.doi.org/10.3390/lubricants10100233.

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Hertzian formulas are commonly used for the evaluation of deformation and pressure distribution of non-conformal and slightly conformal mechanical pairs to estimate component stiffness and durability. For the sake of simplicity, their use is extended even to those cases in which Hertz’s hypotheses do not hold. This paper summarizes Hertz’s theory and compares the results obtained with theoretical and finite element analysis of the point contact of non-conformal and conformal pairs made of spheres, caps, and spherical seats. This study was motivated by the non-Hertzian behavior of a tilting pad bearing ball-and-socket pivot conforming contact observed by the authors in previous experiments. In particular, the displacement and force relation were investigated by varying the geometrical parameters, the materials, the boundary conditions, and the friction coefficient. In the case of non-conformal contact, the parameter variations had negligible effect in agreement with Hertz’s theory while for conformal contact, the cap and seat height and width and the relative clearance were the most influential parameters on the non-Hertzian behavior. These novel results indicate that in conformal pairs, such as for tilting pad bearing ball-and-socket pivots, whenever Hertz’s hypotheses are not satisfied and the assessment of contact stiffness is crucial, Hertzian formulas should not be applied as done in common practice, instead more accurate numerical or experimental evaluation should be made.

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MARTIN, RAFAEL GOMEZ, JUAN A. MORENTE, and AMELIA R. BRETONES. "Arrays of hertzian electric dipoles for non-sinusoidal signals." International Journal of Electronics 59, no. 4 (October 1985): 435–38. http://dx.doi.org/10.1080/00207218508920714.

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Більше джерел

Дисертації з теми "Non-Hertzian"

Pecile, Bérénice. "Modèle dynamique d'interaction véhicule-voie ferroviaire en présence de défauts géométriques sur les surfaces en contact." Thesis, Valenciennes, 2017. http://www.theses.fr/2017VALE0004/document.

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Les phénomènes dynamiques observés lors de la circulation des trains provoquent des nuisances, notamment sonores et vibratoires, qui sont amplifiées par la présence de défauts sur la roue et sur le rail. Pour les analyser, il est nécessaire de prédire avec robustesse le comportement dynamique des composants impliqués dans l’interaction véhicule-voie et donc de simuler les efforts de contact générés pour des interfaces non idéalisées.L’objectif de cette thèse est donc de proposer un modèle semi-analytique global compatible avec l’intégration de multiples défauts géométriques sur les surfaces en contact. Afin de simuler l’interaction véhicule-voie dans le domaine temporel et garantir une applicabilité en phase de dimensionnement, une attention particulière est portée sur le compromis entre la précision des résultats et les temps de calcul associés.Le modèle ainsi proposé est composé d’un demi-bogie, dont le comportement vertical est représenté par un ensemble de masses-ressorts-amortisseurs, circulant sur une voie ballastée. Cette dernière est assimilée à une poutre bi-appuyée, supportée périodiquement à l’emplacement des traverses. Ces deux systèmes sont couplés en contact grâce à une procédure Distributed Point Reacting Spring (DPRS) sous forme discrétisée.Une validation du modèle est, d’une part, proposée en considérant des travaux antérieurs dans le cas de géométries parfaites. D’autre part, de multiples combinaisons de défauts, localisés comme le méplat ou répartis comme l’usure ondulatoire, sont introduites dans la simulation. La variabilité spatiale, particulière au cas de l’écaillage, est modélisée par des champs aléatoires
The appearance of dynamic phenomena during the running of train on track leads to issues such as noise and vibration pollution, which can be further amplified by the presence of defects on the treads. In order to analyze them, it is necessary to predict with reliability the dynamic behavior of the vehicle-track interaction components, in particular the contact forces produced by non perfect treads.The aim of this PhD thesis is to provide a semi-analytical vehicle-track interaction model able to take into account multiple defects on the surfaces in contact. In order to conduct simulations in the time-domain and ensure applicability in the sizing phase, a special attention is given on the compromise between the accuracy of the results and the simulation times.The proposed model is therefore composed of half a bogie running on a ballasted track. This latter is modeled by a pinned-pinned beam with periodic supports located at the sleepers while the vertical behavior of the bogie is given by masses, springs and dampers. These two models are coupled in contact by a discretized Distributed Point Reacting Spring (DPRS) procedure.A validation of the model, based on previous work, is firstly proposed for perfect treads. Then, multiple combinations of defects, either localised as wheelflat or spread as corrugation, are introduced in the simulation. The spatial variability, specific to shelling, is modeled by random fields

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Mavel, Sébastien. "Développement d'un outil de pré dimensionnement de structures sandwich soumises à des impacts à vitesse intermédiaire." Phd thesis, Université de Valenciennes et du Hainaut-Cambresis, 2012. http://tel.archives-ouvertes.fr/tel-00760613.

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Dans le cadre du développement d'un outil semi-analytique de pré-dimensionnement de structures sandwich soumises à des impacts à vitesse intermédiaire (<20m.s-1), nous proposons la détermination d'une solution efficace, basée sur les séries de Fourier avec des conditions aux limites générales. Les équations gouvernantes qui permettent de décrire la réponse transitoire élastique de plaques stratifiées orthotropes avec prise en compte d'une loi non linéaire de contact hertzien sont développées en utilisant un schéma de discrétisation temporelle explicite. Pour les conditions aux limites générales, la solution en séries de Fourier est complétée par une série mixte de polynômes-cosinus, qui permet d'aboutir à la solution, tout en permettant à la série de satisfaire les équations d'équilibres ainsi que les conditions limites, de façon exacte en augmentant le nombre de termes de la série. Afin de tenir compte des phénomènes physiques locaux lors de l'impact de structure sandwich, la plasticité et la rupture locale de la plaque anti-perforation sont introduites dans une formulation modifiée du contact de Hertz et l'écrasement de l'âme du sandwich est ajouté dans l'équation d'équilibre du projectile. Les solutions obtenues par cette méthode sont en accord avec les résultats par modélisation éléments finis de plaques composites multicouches impactées par un projectile. Une campagne expérimentale d'impact de type " box corner " sur des plaques sandwich de 1m², a servi de référence expérimentale et permis la validation de ce modèle complet. Finalement, le couplage de ce modèle à un optimiseur basé sur les techniques de plans d'expériences et de surfaces de réponses (métamodèles), nous a permis de choisir la meilleure structure d'absorption d'énergie (matériaux et géométrie) pour des structures plaques soumises à des impacts de 7kJ. Un test sur un véhicule réel avec la configuration structurelle choisie, nous a permis de valider l'outil final de pré-dimensionnement et de confirmer la qualité des résultats numériques obtenus par ce modèle semi-analytique.

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Votsios, Vasilis. "Contact mechanics and impact dynamics of non-conforming elastic and viscoelastic semi-infinite or thin bonded layered solids." Thesis, Loughborough University, 2003. https://dspace.lboro.ac.uk/2134/11815.

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The thesis is concerned with the contact mechanics behaviour of non-conforming solids. The geometry of the solids considered gives rise to various contact configurations, from concentrated contacts with circular and elliptical configuration to those of finite line nature, as well as those of less concentrated form such as circular flat punches. The radii of curvature of mating bodies in contact or impact give rise to these various nonconforming contact configurations and affect their contact characteristics, from those considered as semi-infinite solids in accord with the classical Hertzian theory to those that deviate from it. Furthermore, layered solids have been considered, some with higher elastic modulus than that of the substrate material (such as hard protective coatings) and some with low elastic moduli, often employed as tribological coatings (such as solid lubricants). Other bonded layered solids behave in viscoelastic manner, with creep relaxation behaviour under load, and are often used to dampen structural vibration upon impact. Analytic models have been developed for all these solids to predict their contact and impact behaviour and obtain pressure distribution, footprint shape and deformation under both elastostatic and transient dynamic conditions. Only few solutions for thin bonded layered elastic solids have been reported for elastostatic analysis. The analytical model developed in this thesis is in accord with those reported in the literature and is extended to the case of impact of balls, and employed for a number of practical applications. The elastostatic impact of a roller against a semi-infinite elastic half-space is also treated by analytic means, which has not been reported in literature. Two and three-dimensional finite element models have been developed and compared with all the derived analytic methods, and good agreement found in all cases. The finite element approach used has been made into a generic tool for all the contact configurations, elastic and viscoelastic. The physics of the contact mechanical problems is fully explained by analytic, numerical and supporting experimentation and agreement found between all these approaches to a high level of conformance. This level of agreement, the development of various analytical impact models for layered solids and finite line configuration, and the development of a multi-layered viscoelastic transducer with agreed numerical predictions account for the main contributions to knowledge. There are a significant number of findings within the thesis, but the major findings relate to the protective nature of hard coatings and high modulus bonded layered solids, and the verified viscoelastic behaviour of low elastic modulus compressible thin bonded layers. Most importantly, the thesis has created a rational framework for contact/impact of solids of low contact contiguity.

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Rajendrakumar, P. K. "Analysis Of Non-Hertzian Contact Between Rough Surfaces." Thesis, 1997. http://etd.iisc.ernet.in/handle/2005/2149.

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Chang, Yuan-Che, and 張元哲. "NUMERICAL SOLUTION OF NON-HERTZIAN CONTACT STRESS FOR AN ELASTIC HALF SPACE." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/81033605246735846205.

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碩士
國立中央大學
機械工程研究所
83
In the study and design of mechine elements,it is often desirable to have detailed knowledge of contact stress and contact area. Numerous machine and structural components make contact over an extremely small area. Example of such components include rolling and cams. A general method of numerical method will be described for the analysis of the contact between a rigid plane and a li- near elastic cylinder materials. Based on the generalized Boussinesq solution for a half space, displacement and pressure influence coefficients will be formulated for a uniformly distributed load applied over a rectangular area on the surface of a rigid plane. Hertzian and non-Hertzian elastic contact problem is considered. That is, friction is considered in non-Hertzian contact. The sur- face pressure and contact area are obtained. The contact stress and contact area between a rigid plane and a cylinder for both steel and rubber materials are mo- deled. Finally,the numerical results are compared with Hertz formula and Lindly's experimental results.

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Частини книг з теми "Non-Hertzian"

Karami, Ghodratollah. "Non-Hertzian Contact Problems." In Lecture Notes in Engineering, 145–203. Berlin, Heidelberg: Springer Berlin Heidelberg, 1989. http://dx.doi.org/10.1007/978-3-642-83897-2_6.

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Perret-Liaudet, J., and J. Sabot. "Vibro-impacts induced by non-linear resonances in hertzian contacts." In Dynamics of Vibro-Impact Systems, 251–60. Berlin, Heidelberg: Springer Berlin Heidelberg, 1999. http://dx.doi.org/10.1007/978-3-642-60114-9_28.

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Qazi, Aquib, Michel Sebès, Hugues Chollet, Honoré Yin, and Cédric Pozzolini. "An Extension of FASTSIM for Steady State Non-Hertzian Contact." In Lecture Notes in Mechanical Engineering, 500–512. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-07305-2_50.

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Mbarek, Ayoub, Ahmed Hammami, Alfonso Fernández del Rincón, Fakher Chaari, Miguel Iglesias, Fernando Viadero Rueda, and Mohamed Haddar. "Influence of the Non-linear Hertzian Stiffness on the Dynamic Behavior of Planetary Gear During Run up Condition." In Applied Condition Monitoring, 30–38. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-11220-2_4.

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Perret-Liaudet, J., and E. Rigaud. "Non Linear Dynamic Behaviour of an One-Sided Hertzian Contact Excited by an External Gaussian White Noise Normal Excitation." In Vibro-Impact Dynamics of Ocean Systems and Related Problems, 215. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-642-00629-6_21.

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"Non-Hertzian normal contact of elastic bodies." In Contact Mechanics, 107–52. Cambridge University Press, 1985. http://dx.doi.org/10.1017/cbo9781139171731.006.

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Тези доповідей конференцій з теми "Non-Hertzian"

Liu, C. H., and W. E. Hsu. "Non-Hertzian rolling contact stress analysis." In CMEM 2007. Southampton, UK: WIT Press, 2007. http://dx.doi.org/10.2495/cmem070571.

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Guan, Qinghua, Binbin Liu, and Stefano Bruni. "Effects of Non-Hertzian Contact Models on Derailment Simulation." In 2020 Joint Rail Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/jrc2020-8074.

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Abstract The derailment of trains is a complex phenomenon that requires an elaborate contact model in simulation to better understand its mechanism. The CONTACT program is a well-known reference for wheel-rail contact modeling due to its high accuracy. However, its low computational efficiency restricts its applications especially in the context of a multi-body simulation. Therefore, a high computational efficient, simplified and approximate non-Hertzian contact is preferred in derailment simulation. The aim of this research is to verify the efficiency of a recently developed non-Hertzian wheel-rail contact model in derailment simulation, which is a combination of the Kik-Piotrowski model and the KBTNH that is a fast creep force solver for non-Hertzian contacts. To assess the performance of the non-Hertzian model in derailment simulation, the derailment coefficient for steady-state and quasi-steady conditions, the wheel/rail contact forces during flange contact, and the dynamics behaviors of the wheelset prior to the derailment are compared with the state of the art contact methods representing different levels of modeling complexity, accuracy and efficiency, namely the classical approach (Hertz theory+FASTSIM algorithm) and the ‘exact’ solver CONTACT.

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Lin, David C., Emilios K. Dimitriadis, and Ferenc Horkay. "Elasticity of Cartilage Measured by Large Strain, Non-Hertzian AFM Nanoindentation." In ASME 2007 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2007. http://dx.doi.org/10.1115/sbc2007-176618.

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The raster scanning and nanoindentation capabilities of the AFM are exploited in force spectroscopy, a valuable quantitative technique for mapping the elastic properties of materials down to nanometer resolution. When the probe is of well-defined geometry and the indentation behavior can be represented by established contact mechanics models, the force maps can be transformed to elastic modulus maps to facilitate comparison. This is especially important in biological specimens, where sample-to-sample variability is usually high.

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Tanaka, Takayuki, and Hiroyuki Sugiyama. "Numerical Procedure for Non-Hertzian Wheel-Rail Contact Model Integrated in Quasi-Steady Railway Vehicle Motion Solver." In ASME 2020 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/detc2020-22066.

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Abstract Although the Hertzian contact theory is widely utilized in railway vehicle simulations with new wheel and rail profiles, the Hertzian contact assumptions would lead to inaccurate contact prediction for severely worn wheel and rail profiles due to their geometric conformity, causing non-elliptical contact shapes as well as pressure distribution. For this reason, various non-Hertzian contact models have been studied for use in vehicle dynamics simulations. Among others, a method proposed by Piotrowski and Kik has gained acceptance in predicting non-elliptical wheel-rail contact for vehicle dynamics simulations. Despite the elegant formulation and its accuracy, detailed online geometric calculation for non-elliptical contact shape is required for all the contact patches at every iteration, along with iterative evaluation of the force-deflection relationship. It leads to computation burdens for use in long-distance vehicle simulations. Therefore, in this study, an off-line based numerical procedure for non-Hertzian contact model is developed and integrated in the quasi-steady railway vehicle motion solver.

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Navarro, Helio A., Jose M. Balthazar, and Reyolando M. L. R. F. Brasil. "Vibrations due to Impact in a Non Ideal Mechanical System With a Non-Linear Hertzian Contact Model." In ASME 2014 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/detc2014-34145.

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This work analyses the post impact behavior of a mechanical system consisting of an oscillator and an unbalanced non–ideal electrical motor. The impact between the mechanical system and a rigid wall is based on the assumption that the impacting bodies undergo local deformations. The method used in the present work is similar to the Discrete Element Method for particle systems modeled with a “soft–sphere” mechanism. The contact forces are modeled using a nonlinear damped Hertzian Spring-Dashpot system. The mathematical model of the mechanical system is represented by a set of nonlinear ordinary differential equations. The transient and steady-state responses are discussed. As the motor is considered a non ideal energy source, the Sommerfeld effect is also analyzed. The impact model is first applied for a single freely falling particle and then in the proposed mechanical system. Non-dimensional expressions for the contact force and numerical simulations of the mechanical system behavior are also presented.

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Rigaud, Emmanuel, and Joël Perret-Liaudet. "Experimental Response of a Preloaded Vibro-Impacting Hertzian Contact." In ASME 2001 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/detc2001/vib-21547.

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Abstract This paper concerns the non-linear dynamic response of a vibro-impacting Hertzian contact. Sinusoidal and random external normal forces are considered. We focus on the primary resonance and include vibro-impact responses in order to analyze the main characteristics of the system associated to both Hertzian and contact loss non-linearities. Under very small input amplitude, contact exhibits an almost linear resonance. Linearized resonance frequency and damping ratio are identified. Increasing the external input amplitude, the softening behaviour induced by Hertzian nonlinear stiffness is clearly demonstrated for both sinusoidal and random inputs. For higher input amplitude, system exhibits vibro-impacts. The contact loss non-linearity strongly governs the dynamic behaviour of the system.

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Gómez-Bosch, Jorge, Juan Giner-Navarro, and Javier Carballeira. "On the calculation of the Kalker's creep coefficients for non-elliptical contact areas." In VI ECCOMAS Young Investigators Conference. València: Editorial Universitat Politècnica de València, 2021. http://dx.doi.org/10.4995/yic2021.2021.12313.

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In order to properly analyse new challenges in railway dynamics, such as corrugation or rolling noise, it is necessary to obtain an accurate solution of the tangential contact problem. Traditionally, in most railway dynamic softwares, tangential contact has been calculated based on the FASTSIM algorithm. This method provides a fairly accurate solution with reduced computational cost. However, when non-Hertzian contact conditions have to be assumed, its calculations are no longer accurate, which makes FASTSIM not useful for this purpose. Also, there exist tangential contact models which are able to obtain an accurate solution for non-Hertzian conditions, but their computational cost makes them inappropriate for dynamic calculations. Therefore, this proposed new method is developed in order to satisfy the need of a model able to obtain results under non-Hertzian conditions, without an excessive computational cost.In the present work, a new extension of the FASTSIM method for the calculation of non-elliptical contact areas is proposed. The main complexity of this method lies on the calculation of the adhesion coefficients. Originally, these coefficients are obtained from Kalker’s Linear Theory, which gives exact results for elliptical contact areas, but its accuracy lowers under non-Hertzian conditions. To obtain them, a stationary contact model which assumes infinite friction coefficient is developed. This model is obtained from the kinematics of the different configurations of the wheel and the rail, and from the constitutive relations corresponding to an infinite half-space. This model is solved numerically by a collocation method (imposing the solution over the contact area). By comparison with the results obtained with reference models, the accuracy and computational cost of the proposed model is analysed. These comparisons show that the proposed model is 50 times faster than the reference model, and the errors are under 3% in most of the carried-out analysis.

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Marques Flavio, Paulo Guilherme, and Thiago Doca. "NUMERICAL STUDY OF A PLANE SURFACE-HALF SPHERE UNDER TWO DIFFERENT APPROACHES: HERTZIAN CONSIDERATION AND NON-LINEAR." In 25th International Congress of Mechanical Engineering. ABCM, 2019. http://dx.doi.org/10.26678/abcm.cobem2019.cob2019-1662.

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Perret-Liaudet, Joe¨l, and Emmanuel Rigaud. "Superharmonic Resonance of Order 2 for an Impacting Hertzian Contact Oscillator: Theory and Experiments." In ASME 2005 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2005. http://dx.doi.org/10.1115/detc2005-84989.

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The purpose of this paper is to investigate experimental responses of a preloaded vibroimpact Hertzian contact to an order 2 superharmonic excitation. A test rig is used, corresponding to a double sphere-plane contact preloaded by the weight of a moving body. Typical response curves are obtained kinder the superharmonic excitation. The Hertzian non linearity constitutes the precursor of vibroimpacts established over a wide frequency range. This behaviour can be related to the existence of a transcritical bifurcation. In conjuction with the experiments, numerical results lead to the same conclusion. In particular, the threshold level of the excitation necessary to induce vibroimpact is confirmed.

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Berger, E. J., S. Tripathy, K. Vemaganti, Y. M. Kolambkar, H. X. You, and K. Courtney. "An Atomic Force Microscopy Indentation Study of Biomaterial Properties." In World Tribology Congress III. ASMEDC, 2005. http://dx.doi.org/10.1115/wtc2005-63244.

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Atomic force microscopy (AFM) is a powerful and increasingly common modality of biomechanical investigation, including imaging, force spectroscopy, and microrheology. AFM indentation of biomaterials requires use of a contact model for data interpretation and material property extraction, and a large segment of the scientific community uses the Hertz model or a close relative for small-scale indentation of thin, soft materials in high strain applications. We present experimental results and analytical/numerical modeling which lead to two main conclusions: (i) Hertzian mechanics are useful in a surprisingly large parameter range, including scenarios in which the underlying assumptions are seemingly violated, and (ii) the Hertz solution serves as a useful base from which power-series type solutions can be derived for a variety of non-Hertzian effects.

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Звіти організацій з теми "Non-Hertzian"

Pailino, Lia, Lihua Lou, Alberto Sesena Rubfiaro, Jin He, and Arvind Agarwal. Nanomechanical Properties of Engineered Cardiomyocytes Under Electrical Stimulation. Florida International University, October 2021. http://dx.doi.org/10.25148/mmeurs.009775.

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Engineered cardiomyocytes made of human-induced pluripotent stem cells (iPSC) present phenotypical characteristics similar to human fetal cardiomyocytes. There are different factors that are essential for engineered cardiomyocytes to be functional, one of them being that their mechanical properties must mimic those of adult cardiomyocytes. Techniques, such as electrical stimulation, have been used to improve the extracellular matrix's alignment and organization and improve the intracellular environment. Therefore, electrical stimulation could potentially be used to enhance the mechanical properties of engineered cardiac tissue. The goal of this study is to establish the effects of electrical stimulation on the elastic modulus of engineered cardiac tissue. Nanoindentation tests were performed on engineered cardiomyocyte constructs under seven days of electrical stimulation and engineered cardiomyocyte constructs without electrical stimulation. The tests were conducted using BioSoft™ In-Situ Indenter through displacement control mode with a 50 µm conospherical diamond fluid cell probe. The Hertzian fit model was used to analyze the data and obtain the elastic modulus for each construct. This study demonstrated that electrically stimulated cardiomyocytes (6.98 ± 0.04 kPa) present higher elastic modulus than cardiomyocytes without electrical stimulation (4.96 ± 0.29 kPa) at day 7 of maturation. These results confirm that electrical stimulation improves the maturation of cardiomyocytes. Through this study, an efficient nanoindentation method is demonstrated for engineered cardiomyocyte tissues, capable of capturing the nanomechanical differences between electrically stimulated and non-electrically stimulated cardiomyocytes.

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