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  • Friction
  • Springer  (8)
  • American Geophysical Union  (2)
  • American Meteorological Society
  • Springer Nature
  • 1990-1994  (10)
  • 1960-1964
  • 1925-1929
Collection
Keywords
Publisher
Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    Issues in computing contact forces for non-penetrating rigid bodies (1993)
    Springer
    Algorithmica 10 (1993), S. 292-352 
    Details
    ISSN: 1432-0541
    Keywords: Simulation ; Dynamics ; Friction ; Optimization ; Configuration space ; Robotics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract In rigid-body simulation it is necessary to compute the forces that arise between contacting bodies to prevent interpenetration. This paper studies the problem of rigid-body simulation when the bodies being simulated are restricted to contact at only finitely many points. Some theoretical and practical issues in computing contact forces for systems with large numbers of contact points are considered. Both systems of rigid bodies with and without Coulomb friction are studied. Complexity results are derived for certain classes of configurations and numerical methods for computing contact forces are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01891843
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Coulomb constitutive laws for friction: Contrasts in frictional behavior for distributed and localized shear (1992)
    Springer
    Pure and applied geophysics 139 (1992), S. 195-214 
    Details
    ISSN: 1420-9136
    Keywords: Friction ; Coulomb failure ; constitutive laws ; localized shear
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract We describe slip-rate dependent friction laws based on the Coulomb failure criteria. Frictional rate dependence is attributed to a rate dependence of cohesionc and friction angle ϕ. We show that differences in the stress states developed during sliding result in different Coulomb friction laws for distributed shear within a thick gouge layer versus localized shear within a narrow shear band or between bare rock surfaces. For shear within gouge, shear strength is given by τ=c cosφ + σ n sinφ, whereas for shear between bare rock surfaces the shear strength is τ=c cosφ + σ n tanφ, where τ and σ n are shear and normal stress, respectively. In the context of rate-dependent Coulomb friction laws, these differences mean that for a given material and rate dependence of the Coulomb parameters, pervasive shear may exhibit velocity strengthening frictional behavior while localized shear exhibits velocity weakening behavior. We derive from experimental data the slip-rate dependence and evolution ofc and ϕ for distributed and localized shear. The data show a positive rate dependence for distributed shear and a negative rate dependence for localized shear, indicating that the rate dependence ofc and ϕ are not the same for distributed and localized shear, even after accounting for differences in stress state. Our analysis is consistent with the well-known association of instability with shear localization in simulated fault gouge and the observation that bare rock surfaces exhibit predominantly velocity weakening frictional behavior whereas simulated fault gouge exhibits velocity strengthening followed by a transition to velocity weakening with increasing displacement. Natural faults also exhibit displacement dependent frictional behavior and thus the results may prove useful in understanding the seismic evolution of faulting.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00876327
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  • 3
    Electronic Resource
    Electronic Resource
    Simulation of the frictional stick-slip instability (1994)
    Springer
    Pure and applied geophysics 143 (1994), S. 61-87 
    Details
    ISSN: 1420-9136
    Keywords: Friction ; earthquakes ; nonlinear dynamics ; lattice solid ; numerical simulation ; numerical modeling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A lattice solid model capable of simulating rock friction, fracture and the associated seismic wave radiation is developed in order to study the origin of the stick-slip instability that is responsible for earthquakes. The model consists of a lattice of interacting particles. In order to study the effect of surface roughness on the frictional behavior of elastic blocks being rubbed past one another, the simplest possible particle interactions were specified corresponding to radially dependent elastic-brittle bonds. The model material can therefore be considered as round elastic grains with negligible friction between their surfaces. Although breaking of the bonds can occur, fracturing energy is not considered. Stick-slip behavior is observed in a numerical experiment involving 2D blocks with rough surfaces being rubbed past one another at a constant rate. Slip is initiated when two interlocking asperities push past one another exciting a slip pulse. The pulse fronts propagate with speeds ranging from the Rayleigh wave speed up to a value between the shear and compressional wave speeds in agreement with field observations and theoretical analyses of mode-II rupture. Slip rates are comparable to seismic rates in the initial part of one slip pulse whose front propagates at the Rayleigh wave speed. However, the slip rate is an order of magnitude higher in the main part of pulses, possibly because of the simplified model description that neglected intrinsic friction and the high rates at which the blocks were driven, or alternatively, uncertainty in slip rates obtained through the inversion of seismograms. Particle trajectories during slip have motions normal to the fault, indicating that the fault surfaces jump apart during the passage of the slip pulse. Normal motion is expected as the asperities on the two surfaces ride over one another. The form of the particle trajectories is similar to those observed in stick-slip experiments involving foam rubber blocks (Brune et al., 1993). Additional work is required to determine whether the slip pulses relate to the interface waves proposed by Brune and co-workers to explain the heat-flow paradox and whether they are capable of inducing a significant local reduction in the normal stress. It is hoped that the progressive development of the lattice solid model will lead to realistic simulations of earthquake dynamics and ultimately, provide clues as to whether or not earthquakes are predictable.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00874324
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  • 4
    Electronic Resource
    Electronic Resource
    Micromechanics of the velocity and normal stress dependence of rock friction (1994)
    Springer
    Pure and applied geophysics 143 (1994), S. 303-315 
    Details
    ISSN: 1420-9136
    Keywords: Friction ; earthquakes ; faulting rock properties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Among the second-order effects on friction the most important are those of variable normal stress and of slip velocity. Velocity weakening, which is usually considered the source of the stick-slip instability in rock friction, has been observed in velocity stepping experiments with Westerly granite. The friction change, Δμ, was −0.01 to −0.008 for a tenfold velocity increase. Using normal closure measurements, we observed dilation upon each increase in sliding rate. We also observed, for the first time, time-dependent closure between surfaces during static loading. The dilation that occurred during the velocity stepping experiment was found to be that expected from the static time-dependent closure phenomenon. This change in closure was used to predict friction change with an elastic contact model. The calculated friction change which results from a change in contact area and asperity interlocking, is in good agreement with the observed velocity dependence of steady-state friction. Variable normal stress during sliding has two effects, first in creating new partial slip contacts and locking some existing fully sliding contacts and second in increasing interlocking, for instance when normal load is suddenly increased. As a result, a transient change in friction occurs upon a sudden change in normal load.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00874333
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  • 5
    Electronic Resource
    Electronic Resource
    Direct observation of frictional contacts: New insights for state-dependent properties (1994)
    Springer
    Pure and applied geophysics 143 (1994), S. 283-302 
    Details
    ISSN: 1420-9136
    Keywords: Friction ; fault properties ; contact mechanics ; state dependence ; characteristic sliding distance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Rocks and many other materials display a rather complicated, but characteristic, dependence of friction on sliding history. These effects are well-described by empirical rate- and state-dependent constitutive formulations which have been utilized for analysis of fault slip and earthquake processes. We present a procedure for direct quantitative microscopic observation of frictional contacts during slip. The observations reveal that frictional state dependence represents an increase of contact area with contact age. Transient changes of sliding resistance correlate with changes in contact area and arise from shifts of contact population age. Displacement-dependent replacement of contact populations is shown to cause the diagnostic evolution of friction over a characteristic sliding distance that occurs whenever slip begins or sliding conditions change.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00874332
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  • 6
    Electronic Resource
    Electronic Resource
    Velocity weakening in a dynamical model of friction (1994)
    Springer
    Pure and applied geophysics 142 (1994), S. 447-466 
    Details
    ISSN: 1420-9136
    Keywords: Friction ; velocity weakening ; spring-block models
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract We introduce a discrete model for friction between rough elastic surfaces which is based on the microscopic description of contacts between asperities. Rough surfaces are modeled as spring-mass arrays with superposed asperities. The linear elastodynamics of the underlying surfaces is treated in the model separately from the nonlinear contact behavior of asperities. Unlike usual spring-block models, noa priori friction law is imposed in the model, which allows the frictional behavior corresponding to a chosen microscopic physics of contacts and topography of the rough surfaces to be simulated. We use the model to study the elastodynamical mechanism of friction related to the inertial response of the elastic medium to suddenly imposed tractions, and perturbations of contact properties due to the elastic waves propagating along the interface. The contribution of this mechanism to friction becomes important at high slip rates (above 1% of the wave speed in our simulations), where it results in the velocity weakening behavior. The mechanism of velocity weakening is first studied analytically on an isolated model element. The predicted behavior is then reproduced in numerical simulations with large surfaces. Simulations with stepping of the driving velocity demonstrate a difference between the frictional force measured directly on contacts, and at the loading point. The latter corresponds to laboratory measurements and includes the inertial response of both the loading mechanism and the elastic body to the variations of driving velocity. We speculate that a similar inertial response is present in certain experimental data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00876050
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  • 7
    Electronic Resource
    Electronic Resource
    The micromechanics of friction in a granular layer (1994)
    Springer
    Pure and applied geophysics 142 (1994), S. 777-794 
    Details
    ISSN: 1420-9136
    Keywords: Friction ; gouge ; stick-slip ; granular mechanics ; earthquake mechanics ; fragmentation ; cataclasis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A grain bridge model is used to provide a physical interpretation of the rate- and state-dependent friction parameters for the simple shear of a granular layer. This model differs from the simpler asperity model in that it recognizes the difference between the fracture of a grain and the fracture of an adhesion between grains, and it explicitly accounts for dilation in the granular layer. The model provides an explanation for the observed differences in the friction of granular layers deformed between rough surfaces and those deformed between smooth surfaces and for the evolution of the friction parameters with displacement. The observed evolution from velocity strengthening to velocity weakening with displacement is interpreted as being due to the change in the micromechanics of strain accommodation from grain crushing to slip between adjacent grains; this change is associated with the observed evolution of a fractal grain structure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00876064
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  • 8
    Electronic Resource
    Electronic Resource
    Origin of rate dependence in frictional sliding (1991)
    Springer
    Journal of statistical physics 65 (1991), S. 403-412 
    Details
    ISSN: 1572-9613
    Keywords: Friction ; critical phenomena ; earthquakes ; self-organized criticality ; scaling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Experiments indicate that frictional resistance to sliding between macroscopic, clean, dry surfaces depends on the average rateV at which the surfaces are translated relative to each other. Using a new lattice automaton, we obtain results suggesting that rate-dependent macroscopic dynamics may arise from microscopic interactions between contact points which decay from a metastable state with a finite lifetimeΓ. Sliding is accommodated by clusters, or avalanches, of failed lattice contact points, and corresponds to successive quenches into the metastable state by an electromechanical loading system with a finite response timeΔ. Under the quasistatic assumptionΔ ≫Γ, rate dependence is a consequence of the increase in correlation length ξd of clusters of failed lattice points as quench rate increases. Special cases of the model are isomorphic to the selforganized criticality model for sandpiles, and to block-spring models of the type first studied by Burridge and Knopoff for earthquakes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01329869
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  • 9
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    Nonlinear dynamics of the transition from stable sliding to cyclic stick-slip in rock (1994)
    American Geophysical Union
    In:  Professional Paper, Nonlinear Dynamics and Predictability of Geophysical Phenomena, Washington, American Geophysical Union, vol. 65, no. 16, pp. 15-35, (ISBN: 3-540-23712-7)
    Details
    Publication Date: 1994
    Keywords: Non-linear effects ; Friction ; Fracture ; Physical properties of rocks
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    BIBLIOGRAPHY SEISMOLOGY
  • 10
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    Period-doubling bifurcation and chaotic phenomena in a single degree of freedom elastic system with a two-state variable friction law (1994)
    American Geophysical Union
    In:  Professional Paper, Open-File Rept., Nonlinear Dynamics and Predictability of Geophysical Phenomena, Washington, American Geophysical Union, vol. 4, no. 2, pp. 75-80, (ISBN 0080419208)
    Details
    Publication Date: 1994
    Keywords: Chaotic behaviour ; Friction
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    BIBLIOGRAPHY SEISMOLOGY
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