one-body-sample.parset

# -*- mode:conf -*-
timesteps = 1000

verbose = false
printCoefficient = false
printFrictionalVelocity = false
printProgress = false

writeEvolution = false
writeVTK = false

printVelocitySteppingComparison = false

enable_timer = false

timeSteppingScheme = implicitEuler

[grid]
refinements = 4

[body]
E = 5e7
nu = 0.3 # The close we get to 0.5, the more wiggly everything gets

[solver]
tolerance = 1e-10

[solver.tnnmg]
maxiterations = 1 # Krause modification; old: 1000000
fixed_point_iterations = 10000
fixed_point_tolerance = 1e-10

[solver.tnnmg.linear]
maxiterations = 1000000
nu1 = 1
mu = 1
nu2 = 1

[solver.tnnmg.main]
nu1 = 1
mu = 1 # Krause modification; old: 4
nu2 = 0 # Krause modification; old: 1

[localsolver]
steps = 1

[bisection]
acceptFactor = 1.0
requiredResidual = 1e-12

[boundary.friction]
normalstress = 50000
# "mu_0 is the nominal coefficient of friction that has values near 0.6"
# -- James H. Dieterich and Brian Kilgore: Implications of fault
#    constitutive properties for earthquake prediction
#    http://earthquake.usgs.gov/research/physics/lab/prediction.pdf
mu = 0.6
eta = 1
model = Exponential

[boundary.friction.state]
# log(alpha(0))
initial = 0
model = Dieterich # Ruina

[boundary.friction.ruina]
# "For rocks, typical values of A and B range from 0.005 to 0.015"
# -- Ronaldo I. Borja and Craig D. Foster:
# Continuum mathematical modeling of slip weakening in geological systems
a = 0.010
b = 0.015
# If L is too large, reaching a steady state takes too long
L = 1e-5

# The second-order a and b terms in [..] are very important in
# determining whether sliding is stable or unstable and (in appli-
# cation to the Earth) whether an earthquake or stable creep
# occurs. From [..], velocity strengthening and thus stable creep
# occurs when a is greater than b.  If b > a, instability can occur
# unless the "spring" supplying stress to the fault or sample is too
# stiff
# -- Norman H.  Sleep:
# Application of a unified rate and state friction theory to the
# mechanics of fault zones with strain localization

# If a > b, the overall change of f is positive, the friction is
# velocity-strengthening, and only stable sliding is possible. On the
# other hand, if a < b, the overall change is negative, the friction
# is velocity-weakening, and dynamic instabilities can occur (e.g.,
# Ruina, 1983). The situation a < b provides a necessary but not a
# sufficient condition for instability.
# -- Yehuda Ben-Zion:
# Dynamic ruptures in recent models of earthquake faults