Source code for felupe.mechanics._item
# -*- coding: utf-8 -*-
"""
This file is part of FElupe.
FElupe is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
FElupe 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with FElupe. If not, see <http://www.gnu.org/licenses/>.
"""
from ._helpers import Assemble, Results
[docs]
class FormItem:
r"""An item to be used in a :class:`felupe.Step` with bilinear and optional linear
form objects based on weak-forms with methods for integration and assembly of
vectors / sparse matrices.
Parameters
----------
bilinearform : Form or None, optional
A bilinear form object (default is None). If None, the resulting matrix will be
filled with zeros.
linearform : Form or None, optional
A linear form object (default is None). If None, the resulting vector will be
filled with zeros.
sym : bool, optional
Flag to active symmetric integration/assembly for bilinear forms (default is
False).
args : tuple or None, optional
Tuple with initial optional weakform-arguments (default is None).
kwargs : dict or None, optional
Dictionary with initial optional weakform-keyword-arguments (default is None).
Examples
--------
>>> import felupe as fem
>>> from felupe.math import ddot, sym, trace, grad
>>>
>>> mesh = fem.Cube(n=11)
>>> region = fem.RegionHexahedron(mesh)
>>> field = fem.FieldContainer([fem.Field(region, dim=3)])
>>> boundaries, loadcase = fem.dof.uniaxial(field, clamped=True)
>>>
>>> @fem.Form(v=field, u=field)
... def bilinearform():
... def a(v, u, μ=1.0, λ=2.0):
... δε, ε = sym(grad(v)), sym(grad(u))
... return 2 * μ * ddot(δε, ε) + λ * trace(δε) * trace(ε)
... return [a]
>>>
>>> item = fem.FormItem(bilinearform, linearform=None, sym=True)
>>> step = fem.Step(items=[item], boundaries=boundaries)
>>> job = fem.Job(steps=[step]).evaluate()
See Also
--------
felupe.Form : A function decorator for a linear- or bilinear-form object.
felupe.Step : A Step with multiple substeps.
"""
def __init__(self, bilinearform=None, linearform=None, sym=False, kwargs=None):
self.bilinearform = bilinearform
self.linearform = linearform
self.sym = sym
self.kwargs = kwargs
self.results = Results(stress=False, elasticity=False)
self.assemble = Assemble(vector=self._vector, matrix=self._matrix)
if self.bilinearform is not None:
self.field = self.bilinearform.form.v.field
else:
if self.linearform is not None:
self.field = self.linearform.form.v.field
def _vector(self, field=None, parallel=False):
if field is not None:
self.field = field
if self.linearform is not None:
self.results.force = self.linearform.assemble(
v=self.field, parallel=parallel, kwargs=self.kwargs
)
else:
from scipy.sparse import csr_matrix
self.results.force = csr_matrix((sum(self.field.fieldsizes), 1))
return self.results.force
def _matrix(self, field=None, parallel=False):
if field is not None:
self.field = field
if self.bilinearform is not None:
self.results.stiffness = self.bilinearform.assemble(
v=self.field,
u=self.field,
parallel=parallel,
sym=self.sym,
kwargs=self.kwargs,
)
else:
from scipy.sparse import csr_matrix
size = sum(self.field.fieldsizes)
self.results.stiffness = csr_matrix((size, size))
return self.results.stiffness