branch: devel-tetsuo-add-truss-element-squash
commit 9ac4e7f2fecd7cd6bdf1a390a12d7902ca6d4771
Author: Tetsuo Koyama
AuthorDate: Sun Mar 21 13:41:38 2021 +0900
Add truss problem example
---
interface/tests/python/Makefile.am | 2 +
interface/tests/python/demo_truss.py | 108 +++
2 files changed, 110 insertions(+)
diff --git a/interface/tests/python/Makefile.am
b/interface/tests/python/Makefile.am
index 813753e..c17f64b 100644
--- a/interface/tests/python/Makefile.am
+++ b/interface/tests/python/Makefile.am
@@ -43,6 +43,7 @@ EXTRA_DIST= \
demo_plasticity.py \
demo_plate.py \
demo_unit_disk.py \
+demo_truss.py \
demo_static_contact.py \
demo_dynamic_contact_1D.py \
demo_Mindlin_Reissner_plate.py \
@@ -71,6 +72,7 @@ TESTS = \
check_asm.py\
check_secondary_domain.py \
check_mixed_mesh.py \
+ demo_truss.py \
demo_wave.py\
demo_wave_equation.py \
demo_laplacian.py \
diff --git a/interface/tests/python/demo_truss.py
b/interface/tests/python/demo_truss.py
new file mode 100644
index 000..2f5fb07
--- /dev/null
+++ b/interface/tests/python/demo_truss.py
@@ -0,0 +1,108 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+# Python GetFEM interface
+#
+# Copyright (C) 2021-2021 Tetsuo Koyama.
+#
+# This file is a part of GetFEM
+#
+# GetFEM 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 2.1 of the License, or
+# (at your option) any later version.
+# This program 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 this program; if not, write to the Free Software Foundation,
+# Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
+#
+
+""" 1D Truss problem test
+
+ This program is used to check that python-getfem is working. This is
+ also a good example of use of python-getfem..
+
+ |-> x
+//|EA |-> u0
+//|-+-+=> P
+//|
+ |<---L--->|<---L--->|
+
+ Exact solution of displacement u0 is u0 = (P*x)/(E*A).
+
+ $Id$
+"""
+import getfem as gf
+import numpy as np
+
+#
+# Physical parameters
+#
+E = 21E6 # Young Modulus (N/cm^2)
+A = 9000.0 # Section Area (cm^2)
+L = 2000.0 # Length of element (cm)
+P = 200.0 # Force (N)
+
+#
+# Numerical parameters
+#
+
+elements_degree = 1 # Degree of the finite element methods
+
+#
+# Mesh generation.
+#
+mesh = gf.Mesh("cartesian", np.array([0, L, 2*L]))
+
+#
+# Boundary selection
+#
+
+fleft = mesh.outer_faces_with_direction(v=[-1.0], angle=0.01)
+fright = mesh.outer_faces_with_direction(v=[+1.0], angle=0.01)
+NEUMANN_BOUNDARY = 1
+DIRICHLET_BOUNDARY = 2
+mesh.set_region(NEUMANN_BOUNDARY, fright)
+mesh.set_region(DIRICHLET_BOUNDARY, fleft)
+#
+# Definition of finite elements methods and integration method
+#
+
+mfu = gf.MeshFem(mesh, 1) # Finite element for the elastic displacement
+mfu.set_classical_fem(elements_degree)
+mim = gf.MeshIm(mesh, elements_degree*2) # Integration method
+
+#
+# Model definition
+#
+
+md = gf.Model("real")
+md.add_fem_variable("u", mfu) # Displacement of the structure
+
+# Truss problem
+md.add_initialized_data("D", [E*A])
+md.add_generic_elliptic_brick(mim, "u", "D")
+
+F = mfu.eval(str(P))
+md.add_initialized_fem_data("ForceData", mfu, F)
+md.add_source_term_brick(mim, "u", "ForceData", NEUMANN_BOUNDARY)
+
+md.add_Dirichlet_condition_with_multipliers(mim, "u", elements_degree - 1,
DIRICHLET_BOUNDARY)
+
+#
+# Model solve
+#
+md.solve()
+
+
+#
+# Solution export
+#
+U = md.variable("u")
+
+# Interpolate the exact solution (Assuming mfu is a Lagrange fem)
+Ue = mfu.eval("(" + str(P) + "*x)/(" + str(E) +"*" + str(A) + ")")
+assert np.allclose(U, Ue)
+
