The effect of finite roughness size and bulk thickness on the prediction of rubber friction and contact mechanics

The basic aim in this work is to present a new technique to analyze the contact surfaces developed by the contact between the tires and the structural pavements by numerical simulations, using 3D finite element formulations with contact mechanics. For this purpose, the Augmented Lagrangian method is used. This study is performed just putting the tires on the structural pavement. These tires and the structural pavement are discretized by finite elements under large 3D elastoplastic deformation. The real loads (of aircrafts, trucks or cars) are applied directly on each tire and by contact mechanics procedures, the real contact area between the tires and the pavement surface is computed. The penetration conditions and the contact interfaces are investigated in details. Furthermore, the pressure developed at the contact surfaces is automatically calculated and transferred to the structural pavement by contact mechanics techniques. The purpose of this work research is to show that the contact area is not circular and the finite element techniques can calculate automatically the real contact area, the real geometry and its stresses and strains. In the end of this work, numerical results in terms of geometry, stress and strain are presented and compared to show the ability of the algorithm. These numerical results are also compared with the numerical results obtained by the commercial program ANSYS.

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A 3D study of the contact surface developed by the contact between the tires and the structural pavements DOI: 10.5585/exacta.v6i2.797

Exacta ◽

10.5585/exactaep.v6i2.797 ◽

2009 ◽

Vol 6 (2) ◽

pp. 197-208

Author(s):

Alex Alves Bandeira ◽

Rita Moura Fortes ◽

João Virgílio Merighi

Keyword(s):

Finite Element ◽

Contact Mechanics ◽

Contact Area ◽

Augmented Lagrangian Method ◽

Numerical Results ◽

Real Contact Area ◽

The Real ◽

Real Contact ◽

Commercial Program ◽

Contact Surfaces

The basic aim in this work is to present a new technique to analyze the contact surfaces developed by the contact between the tires and the structural pavements by numerical simulations, using 3D finite element formulations with contact mechanics. For this purpose, the Augmented Lagrangian method is used. This study is performed just putting the tires on the structural pavement. These tires and the structural pavement are discretized by finite elements under large 3D elastoplastic deformation. The real loads (of aircrafts, trucks or cars) are applied directly on each tire and by contact mechanics procedures, the real contact area between the tires and the pavement surface is computed. The penetration conditions and the contact interfaces are investigated in details. Furthermore, the pressure developed at the contact surfaces is automatically calculated and transferred to the structural pavement by contact mechanics techniques. The purpose of this work research is to show that the contact area is not circular and the finite element techniques can calculate automatically the real contact area, the real geometry and its stresses and strains. In the end of this work, numerical results in terms of geometry, stress and strain are presented and compared to show the ability of the algorithm. These numerical results are also compared with the numerical results obtained by the commercial program ANSYS.

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Asperity-based modification on theory of contact mechanics and rubber friction for self-affine fractal surfaces

Friction ◽

10.1007/s40544-021-0485-5 ◽

2021 ◽

Author(s):

Anahita Emami ◽

Seyedmeysam Khaleghian ◽

Saied Taheri

Keyword(s):

Contact Mechanics ◽

Correction Factor ◽

Contact Area ◽

Normal Load ◽

Vertical Displacement ◽

Dynamics Simulation ◽

Real Contact Area ◽

Physical Parameters ◽

Sliding Velocity ◽

Rubber Friction

AbstractModeling the real contact area plays a key role in every tribological process, such as friction, adhesion, and wear. Contact between two solids does not necessarily occur everywhere within the apparent contact area. Considering the multiscale nature of roughness, Persson proposed a theory of contact mechanics for a soft and smooth solid in contact with a rigid rough surface. In this theory, he assumed that the vertical displacement on the soft surface could be approximated by the height profile of the substrate surface. Although this assumption gives an accurate pressure distribution at the interface for complete contact, when no gap exists between two surfaces, it results in an overestimation of elastic energy stored in the material for partial contact, which typically occurs in many practical applications. This issue was later addressed by Persson by including a correction factor obtained from the comparison of the theoretical results with molecular dynamics simulation. This paper proposes a different approach to correct the overestimation of vertical displacement in Persson’s contact theory for rough surfaces with self-affine fractal properties. The results are compared with the correction factor proposed by Persson. The main advantage of the proposed method is that it uses physical parameters such as the surface roughness characteristics, material properties, sliding velocity, and normal load to correct the model. This method is also implemented in the theory of rubber friction. The results of the corrected friction model are compared with experiments. The results confirm that the modified model predicts the friction coefficient as a function of sliding velocity more accurately than the original model.

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Rough contact mechanics for viscoelastic graded materials: The role of small-scale wavelengths on rubber friction

International Journal of Solids and Structures ◽

10.1016/j.ijsolstr.2017.06.008 ◽

2017 ◽

Vol 125 ◽

pp. 276-296 ◽

Cited By ~ 2

Author(s):

Michele Scaraggi ◽

Davide Comingio

Keyword(s):

Contact Mechanics ◽

Small Scale ◽

Graded Materials ◽

Rubber Friction

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Calculation-and-experimental estimation of the role of the frequency ratio in changing the endurance at two-frequency deformation modes

Industrial laboratory Diagnostics of materials ◽

10.26896/1028-6861-2019-85-1-i-64-71 ◽

2019 ◽

Vol 85 (1(I)) ◽

pp. 64-71 ◽

Cited By ~ 1

Author(s):

M. M. Gadenin

Keyword(s):

High Frequency ◽

Experimental Studies ◽

Low Frequency ◽

Reduction Factor ◽

Single Frequency ◽

Cyclic Loads ◽

Small Ratio ◽

Harmonic Components ◽

Deformation Modes

The cycle configuration at two-frequency loading regimes depends on the number of parameters including the absolute values of the frequencies and amplitudes of the low-frequency and high-frequency loads added during this mode, the ratio of their frequencies and amplitudes, as well as the phase shift between these harmonic components, the latter having a significant effect only with a small ratio of frequencies. Presence of such two-frequency regimes or service loading conditions for parts of machines and structures schematized by them can significantly reduce their endurance. Using the results of experimental studies of changes in the endurance of a two-frequency loading of specimens of cyclically stable, cyclically softened and cyclically hardened steels under rigid conditions we have shown that decrease in the endurance under the aforementioned conditions depends on the ratio of frequencies and amplitudes of operation low-frequency low-cycle and high-frequency vibration stresses, and, moreover, the higher the level of the ratios of amplitudes and frequencies of those stacked harmonic processes of loading the greater the effect. It is shown that estimation of such a decrease in the endurance compared to a single frequency loading equal in the total stress (strains) amplitudes can be carried out using an exponential expression coupling those endurances through a parameter (reduction factor) containing the ratio of frequencies and amplitudes of operation cyclic loads and characteristic of the material. The reduction is illustrated by a set of calculation-experimental curves on the corresponding diagrams for each of the considered types of materials and compared with the experimental data.

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High Ripple-Density Resolution for Discriminating Between Rippled and Nonrippled Signals: Effect of Temporal Processing or Combination Products?

Trends in Hearing ◽

10.1177/23312165211010163 ◽

2021 ◽

Vol 25 ◽

pp. 233121652110101

Author(s):

Dmitry I. Nechaev ◽

Olga N. Milekhina ◽

Marina S. Tomozova ◽

Alexander Y. Supin

Keyword(s):

Low Frequency ◽

Noise Signal ◽

Density Variation ◽

Choice Procedure ◽

Masker Level ◽

Reference Signals ◽

Forced Choice Procedure ◽

The Mean ◽

Density Resolution

The goal of the study was to investigate the role of combination products in the higher ripple-density resolution estimates obtained by discrimination between a spectrally rippled and a nonrippled noise signal than that obtained by discrimination between two rippled signals. To attain this goal, a noise band was used to mask the frequency band of expected low-frequency combination products. A three-alternative forced-choice procedure with adaptive ripple-density variation was used. The mean background (unmasked) ripple-density resolution was 9.8 ripples/oct for rippled reference signals and 21.8 ripples/oct for nonrippled reference signals. Low-frequency maskers reduced the ripple-density resolution. For masker levels from −10 to 10 dB re. signal, the ripple-density resolution for nonrippled reference signals was approximately twice as high as that for rippled reference signals. At a masker level as high as 20 dB re. signal, the ripple-density resolution decreased in both discrimination tasks. This result leads to the conclusion that low-frequency combination products are not responsible for the task-dependent difference in ripple-density resolution estimates.

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NMDA Receptor-Dependent Synaptic Activity in Dorsal Motor Nucleus of Vagus Mediates the Enhancement of Gastric Motility by Stimulating ST36

Evidence-based Complementary and Alternative Medicine ◽

10.1155/2012/438460 ◽

2012 ◽

Vol 2012 ◽

pp. 1-11 ◽

Cited By ~ 9

Author(s):

Xinyan Gao ◽

Yongfa Qiao ◽

Baohui Jia ◽

Xianghong Jing ◽

Bin Cheng ◽

...

Keyword(s):

Synaptic Transmission ◽

Gastric Motility ◽

Low Frequency ◽

Synaptic Activity ◽

Motor Nucleus ◽

Dorsal Motor Nucleus ◽

Vagal Reflex ◽

Precise Molecular Mechanism ◽

Lines Of Evidence

Previous studies have demonstrated the efficacy of electroacupuncture at ST36 for patients with gastrointestinal motility disorders. While several lines of evidence suggest that the effect may involve vagal reflex, the precise molecular mechanism underlying this process still remains unclear. Here we report that the intragastric pressure increase induced by low frequency electric stimulation at ST36 was blocked by AP-5, an antagonist of N-methyl-D-aspartate receptors (NMDARs). Indeed, stimulating ST36 enhanced NMDAR-mediated, but not 2-amino-3-(5-methyl-3-oxo-1,2-oxazol-4-yl)propanoic-acid-(AMPA-) receptor-(AMPAR-) mediated synaptic transmission in gastric-projecting neurons of the dorsal motor nucleus of the vagus (DMV). We also identified that suppression of presynapticμ-opioid receptors may contribute to upregulation of NMDAR-mediated synaptic transmission induced by electroacupuncture at ST36. Furthermore, we determined that the glutamate-receptor-2a-(NR2A-) containing NMDARs are essential for NMDAR-mediated enhancement of gastric motility caused by stimulating ST36. Taken together, our results reveal an important role of NMDA receptors in mediating enhancement of gastric motility induced by stimulating ST36.

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The Influence ofNrf2on Cardiac Responses to Environmental Stressors

Oxidative Medicine and Cellular Longevity ◽

10.1155/2013/901239 ◽

2013 ◽

Vol 2013 ◽

pp. 1-10 ◽

Cited By ~ 1

Author(s):

Reuben Howden ◽

Eva Gougian ◽

Marcus Lawrence ◽

Samantha Cividanes ◽

Wesley Gladwell ◽

...

Keyword(s):

Heart Rate ◽

Heart Rate Variability ◽

High Frequency ◽

Low Frequency ◽

Therapeutic Strategies ◽

Environmental Stressors ◽

Total Power ◽

Airborne Pollutants ◽

Cardiac Responses

Nrf2protects the lung from adverse responses to oxidants, including 100% oxygen (hyperoxia) and airborne pollutants like particulate matter (PM) exposure, but the role ofNrf2on heart rate (HR) and heart rate variability (HRV) responses is not known. We hypothesized that genetic disruption ofNrf2would exacerbate murine HR and HRV responses to severe hyperoxia or moderate PM exposures.Nrf2-/-andNrf2+/+mice were instrumented for continuous ECG recording to calculate HR and HRV (low frequency (LF), high frequency (HF), and total power (TP)). Mice were then either exposed to hyperoxia for up to 72 hrs or aspirated with ultrafine PM (UF-PM). Compared to respective controls, UF-PM induced significantly greater effects on HR (P<0.001) and HF HRV (P<0.001) inNrf2-/-mice compared toNrf2+/+mice.Nrf2-/-mice tolerated hyperoxia significantly less thanNrf2+/+mice (~22 hrs;P<0.001). Reductions in HR, LF, HF, and TP HRV were also significantly greater inNrf2-/-compared toNrf2+/+mice (P<0.01). Results demonstrate thatNrf2deletion increases susceptibility to change in HR and HRV responses to environmental stressors and suggest potential therapeutic strategies to prevent cardiovascular alterations.

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Effects of Local Nicotinic Activation of the Superior Colliculus on Saccades in Monkeys

Journal of Neurophysiology ◽

10.1152/jn.00558.2004 ◽

2005 ◽

Vol 93 (1) ◽

pp. 519-534 ◽

Cited By ~ 21

Author(s):

Masayuki Watanabe ◽

Yasushi Kobayashi ◽

Yuka Inoue ◽

Tadashi Isa

Keyword(s):

Superior Colliculus ◽

Reaction Times ◽

Low Frequency ◽

Visually Guided ◽

Population Activity ◽

Affected Area ◽

Movement Field ◽

Neural Interactions ◽

Restricted Region

To examine the role of competitive and cooperative neural interactions within the intermediate layer of superior colliculus (SC), we elevated the basal SC neuronal activity by locally injecting a cholinergic agonist nicotine and analyzed its effects on saccade performance. After microinjection, spontaneous saccades were directed toward the movement field of neurons at the injection site (affected area). For visually guided saccades, reaction times were decreased when targets were presented close to the affected area. However, when visual targets were presented remote from the affected area, reaction times were not increased regardless of the rostrocaudal level of the injection sites. The endpoints of visually guided saccades were biased toward the affected area when targets were presented close to the affected area. After this endpoint effect diminished, the trajectories of visually guided saccades remained modestly curved toward the affected area. Compared with the effects on endpoints, the effects on reaction times were more localized to the targets close to the affected area. These results are consistent with a model that saccades are triggered by the activities of neurons within a restricted region, and the endpoints and trajectories of the saccades are determined by the widespread population activity in the SC. However, because increased reaction times were not observed for saccades toward targets remote from the affected area, inhibitory interactions in the SC may not be strong enough to shape the spatial distribution of the low-frequency preparatory activities in the SC.

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