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tamaas/tests/conftest.py
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#!/usr/bin/env python
# coding: utf-8
# -----------------------------------------------------------------------------
# @author Lucas Frérot <lucas.frerot@epfl.ch>
#
# @section LICENSE
#
# Copyright (©) 2016 EPFL (Ecole Polytechnique Fédérale de
# Lausanne) Laboratory (LSMS - Laboratoire de Simulation en Mécanique des
# Solides)
#
# Tamaas is free software: you can redistribute it and/or modify it under the
# terms of the GNU Lesser General Public License as published by the Free
# Software Foundation, either version 3 of the License, or (at your option) any
# later version.
#
# Tamaas is distributed in the hope that it will be useful, but WITHOUT ANY
# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
# A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
# details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with Tamaas. If not, see <http://www.gnu.org/licenses/>.
# -----------------------------------------------------------------------------
from __future__ import division, print_function
import numpy as np
import tamaas as tm
import pytest
@pytest.fixture(scope="session")
def tamaas_fixture():
tm.initialize()
yield None
tm.finalize()
class HertzFixture:
def __init__(self, n, load):
self.domain_size = 1
self.n = n
self.load = load
self.curvature = 0.1
self.radius = 1. / self.curvature
self.e_star = 1.
self.a = (3 * load / (4 * self.curvature * self.e_star))**(1. / 3.)
self.x = np.linspace(-self.domain_size / 2., self.domain_size / 2., self.n)
self.y = self.x.copy()
self.x, self.y = np.meshgrid(self.x, self.y)
self._computeSurface()
self._computePressure()
self._computeDisplacement()
def _computeDisplacement(self):
r = np.sqrt(self.x**2 + self.y**2)
self.displacement = np.zeros_like(r)
contact = r < self.a
self.displacement[contact] = self.surface[contact]
self.displacement[~contact] = (self.surface[~contact]
+ self.a / (np.pi * self.radius) * np.sqrt(r[~contact]**2
- self.a**2)
+ (r[~contact]**2 - 2 * self.a**2) / (np.pi * self.radius)
* np.arccos(self.a / r[~contact]))
def _computePressure(self):
r = np.sqrt(self.x**2 + self.y**2)
self.pressure = np.zeros_like(r)
contact = np.where(r < self.a)
self.pressure[contact] = 2 * self.e_star / (np.pi * self.radius) \
* np.sqrt(self.a**2 - r[contact]**2)
def _computeSurface(self):
self.surface = -1. / (2 * self.radius) * (self.x**2 + self.y**2)
@pytest.fixture(scope="module")
def hertz(tamaas_fixture):
return HertzFixture(1024, 0.00001)
class WestergaardFixture:
def __init__(self, n, load):
self.domain_size = 1.
self.lamda = 1.
self.delta = 0.1
self.e_star = 1.
self.n = n
self.p_star = np.pi * self.e_star * self.delta / self.lamda
self.load = load * self.p_star
self.a = self.lamda / np.pi * np.arcsin(np.sqrt(self.load / self.p_star))
self.x = np.linspace(-self.domain_size / 2., self.domain_size / 2., self.n, endpoint=False)
self._computeSurface()
self._computePressure()
self._computeDisplacement()
def _computeSurface(self):
self.surface = self.delta * np.cos(2 * np.pi * self.x / self.lamda)
def _computePressure(self):
self.pressure = np.zeros_like(self.surface)
contact = np.where(np.abs(self.x) < self.a)
self.pressure[contact] = 2 * self.load \
* (np.cos(np.pi * self.x[contact] / self.lamda)
/ np.sin(np.pi * self.a / self.lamda)**2) \
* np.sqrt(np.sin(np.pi * self.a / self.lamda)**2 -
np.sin(np.pi * self.x[contact] / self.lamda)**2)
def _computeDisplacement(self):
psi = np.pi * np.abs(self.x) / self.lamda
psi_a = np.pi * self.a / self.lamda
with np.errstate(invalid='ignore'): # get some warnings out of the way
self.displacement = (np.cos(2*psi) + 2 * np.sin(psi) *
np.sqrt(np.sin(psi)**2 - np.sin(psi_a)**2)
- 2 * np.sin(psi_a)**2 *
np.log((np.sin(psi) + np.sqrt(np.sin(psi)**2 - np.sin(psi_a)**2))
/ np.sin(psi_a)))
contact = np.where(np.abs(self.x) < self.a)
self.displacement[contact] = np.cos(2*psi[contact])
self.displacement *= self.load * self.lamda / (np.pi * self.e_star * np.sin(psi_a)**2)
@pytest.fixture(scope="module")
def westergaard(tamaas_fixture):
return WestergaardFixture(19683, 0.1)
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