scholarly journals Spinning rigid bodies driven by orbital forcing: the role of dry friction

2022 ◽  
Author(s):  
Pablo de Castro ◽  
Tiago Araújo Lima ◽  
Fernando Parisio
Keyword(s):  
Dry Friction ◽  
Rigid Bodies ◽  
Orbital Forcing

scholarly journals Spinning Rigid Bodies Driven by Orbital Forcing: The Role of Dry Friction

2021 ◽  
Author(s):  
Pablo de Castro ◽  
Tiago Araújo Lima ◽  
Fernando Parisio
Keyword(s):  
Rigid Body ◽  
Dry Friction ◽  
Initial Conditions ◽  
Rigid Bodies ◽  
The Body ◽  
Driving Frequency ◽  
Orbital Forcing ◽  
Highly Nonlinear ◽  
Dynamical Regimes ◽  
Body Shapes

Abstract A ``circular orbital forcing'' makes a chosen point on a rigid body follow a circular motion while the body spins freely around that point. We investigate this problem for the planar motion of a body subject to dry friction. We focus on the effect called \emph{reverse rotation} (RR), where spinning and orbital rotations are antiparallel. Similar reverse dynamics include the rotations of Venus and Uranus, journal machinery bearings, tissue production reactors, and chiral active particles. Due to dissipation, RRs are possible only as a transient. Here the transient or \emph{flip} time $t_\textrm{f}$ depends on the circular driving frequency $\omega$, unlike the viscous case previously studied. We find $t_\textrm{f}\sim\omega^{\gamma-1}\mu^{-\gamma/2}$, where $\mu$ is the friction coefficient and $\gamma=0$ ($\gamma=2$) for low (high) $\omega$. Whether RRs really occur depends on the initial conditions as well as on $\mu$ and $H$, a geometrical parameter. The critical $H_\textrm{c}(\mu)$ where RRs become possible follows a $q$-exponential with $q\simeq1.9$, a more restrictive RR scenario than in the wet case. We use animations to visualize the different dynamical regimes that emerge from the highly nonlinear dissipation mechanism of dry friction. Our results are valid across multiple investigated rigid body shapes.

scholarly journals Orbital forcing and role of the latitudinal insolation/temperature gradient

2008 ◽  
Vol 32 (2-3) ◽  
pp. 143-165 ◽  
Author(s):  
Basil A. S. Davis ◽  
Simon Brewer
Keyword(s):  
Temperature Gradient ◽  
Orbital Forcing

scholarly journals Ternary Logic of Motion to Resolve Kinematic Frictional Paradoxes

Entropy ◽  
2019 ◽  
Vol 21 (6) ◽  
pp. 620 ◽  
Author(s):  
Michael Nosonovsky ◽  
Alexander D. Breki
Keyword(s):  
Dry Friction ◽  
Sliding Friction ◽  
Rigid Bodies ◽  
Newtonian Mechanics ◽  
Stability Criteria ◽  
Ternary Logic ◽  
Elastic Bodies ◽  
Logic Approach ◽  
Frictional System ◽  
Painlevé Paradoxes

Paradoxes of dry friction were discovered by Painlevé in 1895 and caused a controversy on whether the Coulomb–Amontons laws of dry friction are compatible with the Newtonian mechanics of the rigid bodies. Various resolutions of the paradoxes have been suggested including the abandonment of the model of rigid bodies and modifications of the law of friction. For compliant (elastic) bodies, the Painlevé paradoxes may correspond to the friction-induced instabilities. Here we investigate another possibility to resolve the paradoxes: the introduction of the three-value logic. We interpret the three states of a frictional system as either rest-motion-paradox or as rest-stable motion-unstable motion depending on whether a rigid or compliant system is investigated. We further relate the ternary logic approach with the entropic stability criteria for a frictional system and with the study of ultraslow sliding friction (intermediate between the rest and motion or between stick and slip).

scholarly journals RSA in Spine: A Review

2017 ◽  
Vol 7 (8) ◽  
pp. 811-820 ◽  
Author(s):  
Ali Humadi ◽  
Sulaf Dawood ◽  
Klas Halldin ◽  
Brian Freeman
Keyword(s):  
Systematic Review ◽  
Lumbar Spine ◽  
Range Of Motion ◽  
Rigid Bodies ◽  
Review Of Literature ◽  
Radiostereometric Analysis ◽  
Specific Knowledge ◽  
Spinal Motion ◽  
Vertebral Segment

Study Design: Systematic review of literature. Objectives: This systematic review was conducted to investigate the accuracy of radiostereometric analysis (RSA), its assessment of spinal motion and disorders, and to investigate the limitations of this technique in spine assessment. Methods: Systematic review in all current literature to invesigate the role of RSA in spine. Results: The results of this review concluded that RSA is a very powerful tool to detect small changes between 2 rigid bodies such as a vertebral segment. The technique is described for animal and human studies for cervical and lumbar spine and can be used to analyze range of motion, inducible displacement, and fusion of segments. However, there are a few disadvantages with the technique; RSA percutaneous procedure needs to be performed to implant the markers (and cannot be used preoperatively), one needs a specific knowledge to handle data and interpret the results, and is relatively time consuming and expensive. Conclusions: RSA should be looked at as a very powerful research instrument and there are many questions suitable for RSA studies.

scholarly journals Early Holocene temperature variability in the Nordic Seas: The role of oceanic heat advection versus changes in orbital forcing

2011 ◽  
Vol 26 (4) ◽  
Author(s):  
Bjørg Risebrobakken ◽  
Trond Dokken ◽  
Lars Henrik Smedsrud ◽  
Carin Andersson ◽  
Eystein Jansen ◽  
...  
Keyword(s):  
Temperature Variability ◽  
Early Holocene ◽  
Orbital Forcing ◽  
Heat Advection ◽  
Nordic Seas

scholarly journals The role of orbital forcing, carbon dioxide and regolith in 100 kyr glacial cycles

2011 ◽  
Vol 7 (4) ◽  
pp. 2391-2411 ◽  
Author(s):  
A. Ganopolski ◽  
R. Calov
Keyword(s):  
Nonlinear Response ◽  
Co2 Concentration ◽  
Orbital Forcing ◽  
Orbital Eccentricity ◽  
Glacial Cycles ◽  
Strongly Nonlinear ◽  
Ice Volume ◽  
The North ◽  
Continental Area

Abstract. The origin of the 100 kyr cyclicity which dominates ice volume variations and other climate records over the past million years remains debatable. Here, using a comprehensive Earth system model of intermediate complexity, we demonstrate that both strong 100 kyr periodicity in the ice volume variations and the timing of glacial terminations during past 800 kyr can be successfully simulated as the direct, strongly nonlinear response of the climate-cryosphere system to the orbital forcing alone, if the atmospheric CO2 concentration stays below its typical interglacial value. The existence of long glacial cycles is primarily attributed to the North American ice sheet and requires presence of a large continental area with exposed rocks. We show that the sharp peak in the power spectrum of ice volume at 100 kyr period results from the long glacial cycles being synchronized with the Earth's orbital eccentricity. Although 100 kyr cyclicity can be simulated with a constant CO2 concentration, temporal variability in the CO2 concentration plays an important role in the amplification of the 100 kyr cycles.

Kinematic Approach in the Impact Problem of Rigid Bodies

1989 ◽  
Vol 42 (11S) ◽  
pp. S233-S244 ◽  
Author(s):  
A. Sinopoli
Keyword(s):  
Degrees Of Freedom ◽  
Rigid Bodies ◽  
Dynamic Evolution ◽  
Rigid Block ◽  
Subsequent Motion ◽  
The Impact ◽  
Finite Extent ◽  
Kinematic Approach ◽  
Impact Problem

The aim of this work is to analyze, by means of a kinematic approach, the problem of the impact between rigid bodies, when the surfaces involved in the impulsive phenomenon are of finite extent. The formulation here adopted permits to use the Gauss variational principle of “least compulsion” and to formulate the dynamic evolution of the system, after an impact, as a minimization problem. In this case, among all the possible subsequent motions, the real one is that which minimizes the kinetic energy connected to the sudden velocities variations. Interesting results are obtained in the case of the impact between a rigid column (either monolithic or made of several blocks) and a rigid ground. In particular, it can be shown that if the previous motion of a rigid block is a rotation around its base corner edge, the motion after the impact is either a rototranslation or merely a translation, depending on the dimensional ratio. In any case, the subsequent motion is characterized by a component of sliding, so that the impact plays the role of filter between the possible degrees of freedom of the system and, at the same time, determines a possible coupling between rotation and translation. This conclusion is a novelty with respect to the results obtained in other papers [4–6], where a classical approach for the impact has been adopted.

The contribution of micro/nano-tribology to the interpretation of dry friction

2000 ◽  
Vol 214 (1) ◽  
pp. 11-22 ◽  
Author(s):  
K. L. Johnson
Keyword(s):  
Dry Friction ◽  
Sliding Friction ◽  
Surface Force ◽  
The Real ◽  
Real Area Of Contact ◽  
Atomic Force ◽  
Dislocation Mechanics ◽  
Asperity Contacts ◽  
Friction Measurements

Fundamental studies of the mechanics and physics of dry sliding friction between solid surfaces have been impeded in the past by surface roughness and the difficulty of determining the real area of contact. The last decade has seen an explosive development of techniques to study friction at single-asperity contacts in which the real and apparent contact areas coincide. The contribution of these developments to interpreting dry friction is discussed in this paper. Experiments with smooth compliant rubber led to an appreciation of the role of adhesive forces and to including its effects in contact mechanics. Atomically smooth surfaces are obtained in the surface force apparatus (SFA) through the property of mica to cleave on atomic planes, and in the atomic force/friction microscope (AFM) by the use of nanometre size contacts on single crystals. Based on friction measurements in the SFA and AFM, a hypothesis is advanced that sliding of atomically smooth contacts takes place by the nucleation and propagation of dislocation-like defects through the interface. An analysis by Hurtado and Kim [29] using dislocation mechanics suggests a ‘scale effect’ in which friction is governed by resistance to nucleation in very small contacts and by resistance to propagation in larger contacts.

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