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solver_callback.py
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Mon, Nov 11, 23:39

solver_callback.py
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#!/usr/bin/env python3
""" solver_callback.py: solver_callback overload example"""
__author__ = "Nicolas Richart"
__credits__ = [
"Guillaume Anciaux <guillaume.anciaux@epfl.ch>",
"Nicolas Richart <nicolas.richart@epfl.ch>",
]
__copyright__ = "Copyright (©) 2016-2021 EPFL (Ecole Polytechnique Fédérale" \
" de Lausanne) Laboratory (LSMS - Laboratoire de Simulation" \
" en Mécanique des Solides)"
__license__ = "LGPLv3"
import numpy as np
import akantu as aka
class SolverCallback(aka.InterceptSolverCallback):
def __init__(self, model):
super().__init__(model)
self.model = model
mesh = model.getMesh()
left = mesh.getElementGroup("Left").getNodeGroup().getNodes()
right = mesh.getElementGroup("Right").getNodeGroup().getNodes()
position = mesh.getNodes()
self.pair = []
for node_l in left:
node_l = int(node_l)
for node_r in right:
node_r = int(node_r)
if abs(position[node_r, 1] - position[node_l, 1]) < 1e-6:
self.pair.append([node_l, node_r])
blocked_dofs = model.getBlockedDOFs()
self.periodic_K_modif = aka.TermsToAssemble("displacement", "displacement")
matrix_type = self.model.getMatrixType("K")
for p in self.pair:
#blocked_dofs[p[1]] = True
# a u_{i, x} + b u_{j, x} = 0
# self.periodic_K_modif(i*dim + aka._x, i*dim + aka._x, a)
# self.periodic_K_modif(i*dim + aka._x, j*dim + aka._x, b)
self.periodic_K_modif(p[0]*2, p[0]*2, 1)
self.periodic_K_modif(p[0]*2, p[1]*2, -1)
if matrix_type == aka._unsymmetric:
self.periodic_K_modif(p[1]*2, p[0]*2, -1)
self.periodic_K_modif(p[1]*2, p[1]*2, 1)
self.first = True
self.k_release = -1
def assembleMatrix(self, matrix_id):
self.model.assembleMatrix(matrix_id)
if matrix_id == "K":
release = self.model.getDOFManager().getMatrix("K").getRelease()
if release == self.k_release:
return
if self.first:
self.model.getDOFManager().getMatrix("K").saveMatrix("K0.mtx")
self.model.getDOFManager().assemblePreassembledMatrix(
"K", self.periodic_K_modif)
if self.first:
self.model.getDOFManager().getMatrix("K").saveMatrix("K1.mtx")
self.k_release = self.model.getDOFManager().getMatrix("K").getRelease()
self.first = False
def assembleResidual(self):
displacement = self.model.getDisplacement()
force = np.zeros(displacement.shape)
for p in self.pair:
force[p[0], 0] += displacement[p[0], 0] - displacement[p[1], 0]
force[p[1], 0] += displacement[p[1], 0] - displacement[p[0], 0]
self.model.getDOFManager().assembleToResidual('displacement', force, -1.);
self.model.assembleResidual();
# -----------------------------------------------------------------------------
def main():
spatial_dimension = 2
mesh_file = 'bar.msh'
max_steps = 250
time_step = 1e-3
aka.parseInput('material.dat')
# -------------------------------------------------------------------------
# Initialization
# -------------------------------------------------------------------------
mesh = aka.Mesh(spatial_dimension)
mesh.read(mesh_file)
model = aka.SolidMechanicsModel(mesh)
model.initFull(_analysis_method=aka._implicit_dynamic)
model.setBaseName("solver_callback")
model.addDumpFieldVector("displacement")
model.addDumpFieldVector("acceleration")
model.addDumpFieldVector("velocity")
model.addDumpFieldVector("internal_force")
model.addDumpFieldVector("external_force")
model.addDumpField("strain")
model.addDumpField("stress")
model.addDumpField("blocked_dofs")
# -------------------------------------------------------------------------
# boundary conditions
# -------------------------------------------------------------------------
model.applyBC(aka.FixedValue(0, aka._y), "YBlocked")
# -------------------------------------------------------------------------
# initial conditions
# -------------------------------------------------------------------------
displacement = model.getDisplacement()
velocity = model.getVelocity()
nb_nodes = mesh.getNbNodes()
position = mesh.getNodes()
L = 1 # pulse_width
A = 0.01
v = np.sqrt(model.getMaterial(0).getReal('E') /
model.getMaterial(0).getReal('rho'))
k = 0.1 * 2 * np.pi * 3 / L
t = 0.
velocity[:, 0] = k * v * A * np.sin(k * ((position[:, 0] - 5.) - v * t))
displacement[:, 0] = A * np.cos(k * ((position[:, 0] - 5.) - v * t))
# -------------------------------------------------------------------------
# timestep value computation
# -------------------------------------------------------------------------
time_factor = 0.8
stable_time_step = model.getStableTimeStep() * time_factor
print("Stable Time Step = {0}".format(stable_time_step))
print("Required Time Step = {0}".format(time_step))
time_step = stable_time_step * time_factor
model.setTimeStep(time_step)
solver_callback = SolverCallback(model)
solver = model.getNonLinearSolver()
solver.set("max_iterations", 100)
solver.set("threshold", 1e-7)
# -------------------------------------------------------------------------
# loop for evolution of motion dynamics
# -------------------------------------------------------------------------
print("step,step * time_step,epot,ekin,epot + ekin")
for step in range(0, max_steps + 1):
model.solveStep(solver_callback)
#model.solveStep()
if step % 10 == 0:
model.dump()
epot = model.getEnergy('potential')
ekin = model.getEnergy('kinetic')
# output energy calculation to screen
print("{0},{1},{2},{3},{4}".format(step, step * time_step,
epot, ekin,
(epot + ekin)))
return
# -----------------------------------------------------------------------------
if __name__ == "__main__":
main()

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