Hi sfepy development team!
I try to probe the Cauchy stress of my FEM model. But errors occurred when defining the evaluation of the problem.
The full exception went like:
Traceback (most recent call last): File "D:\ProgramFiles\Anaconda3\envs\FEM_39\lib\site-packages\sfepy\base\base.py", line 556, in getitem ii = self.names.index(ii) ValueError: 'ii' is not in list
During handling of the above exception, another exception occurred:
Traceback (most recent call last): File "D:\ProgramFiles\Anaconda3\envs\FEM_39\lib\site-packages\sfepy\discrete\integrals.py", line 53, in get obj = self[name] File "D:\ProgramFiles\Anaconda3\envs\FEM_39\lib\site-packages\sfepy\base\base.py", line 563, in getitem raise IndexError(msg) IndexError: 'ii' is not in list
During handling of the above exception, another exception occurred:
Traceback (most recent call last): File "D:\PycharmWorkSpace\Box girder\FEM.py", line 129, in stress = pb.evaluate('ev_cauchy_stress.ii.girder(m.D, u)', mode='evaluate', File "D:\ProgramFiles\Anaconda3\envs\FEM_39\lib\site-packages\sfepy\discrete\problem.py", line 1829, in evaluate aux = self.create_evaluable(expression, File "D:\ProgramFiles\Anaconda3\envs\FEM_39\lib\site-packages\sfepy\discrete\problem.py", line 1771, in create_evaluable out = create_evaluable(expression, self.fields, materials, File "D:\ProgramFiles\Anaconda3\envs\FEM_39\lib\site-packages\sfepy\discrete\evaluate.py", line 230, in create_evaluable equations = Equations.from_conf({'tmp' : expression}, File "D:\ProgramFiles\Anaconda3\envs\FEM_39\lib\site-packages\sfepy\discrete\equations.py", line 65, in from_conf eq = Equation.from_desc(name, desc, variables, regions, File "D:\ProgramFiles\Anaconda3\envs\FEM_39\lib\site-packages\sfepy\discrete\equations.py", line 743, in from_desc terms = Terms.from_desc(term_descs, regions, integrals) File "D:\ProgramFiles\Anaconda3\envs\FEM_39\lib\site-packages\sfepy\terms\terms.py", line 218, in from_desc term = Term.from_desc(constructor, td, region, integrals=integrals) File "D:\ProgramFiles\Anaconda3\envs\FEM_39\lib\site-packages\sfepy\terms\terms.py", line 354, in from_desc integral = integrals.get(desc.integral) File "D:\ProgramFiles\Anaconda3\envs\FEM_39\lib\site-packages\sfepy\discrete\integrals.py", line 56, in get raise ValueError('integral %s is not defined!' % name) ValueError: integral ii is not defined!
However, I have defined the integral ii in the code. The full code is listed below:
from __future__ import absolute_import import numpy as np import pandas as pd from sfepy.base.base import IndexedStruct from sfepy.discrete import (FieldVariable, Material, Integral, Function, Equation, Equations, Problem) from sfepy.discrete.conditions import Conditions, EssentialBC from sfepy.discrete.fem import Mesh, FEDomain, Field from sfepy.mechanics.matcoefs import stiffness_from_youngpoisson from sfepy.solvers.ls import ScipyDirect from sfepy.solvers.nls import Newton from sfepy.terms import Term from sfepy.base.base import Struct from sfepy.postprocess.probes_vtk import Probe from six.moves import range
hf = 1 wf = 2 hr = 5 wr = 1 hs = 1 ws = 6 theta = 0.25 * np.pi span_len = 2 p = -0.5 * 28.14 / (wf + (hr + hs) / np.tan(theta) + ws * 0.5)
def get_bearing_point(coors, domain=None): coord_df = pd.DataFrame(coors) bottom_coord = coord_df[(coord_df[2] == coord_df[2].min()) & (coord_df[1] == coord_df[1].min())] # 梁端底面 min_x = bottom_coord[0].min() max_x = bottom_coord[0].max() x_1_4 = (max_x - min_x) / 4 + min_x x_3_4 = 3 * (max_x - min_x) / 4 + min_x bearing_point_1 = bottom_coord[abs(bottom_coord[0] - x_1_4) < 0.5] bearing_point_2 = bottom_coord[abs(bottom_coord[0] - x_3_4) < 0.5] flag = np.array( list(set( list(bearing_point_1.index) + list(bearing_point_2.index) )) ) return flag
def linear_compress(ts, coor, pressure, mode=None, **kwargs): if mode == 'qp': val = np.tile(-1 * pressure, (coor.shape[0], 1, 1))
return {'val': val}pressure = Function('linear_compress', linear_compress, extra_args={'pressure': p})
functions = { 'get_bearing_point': (get_bearing_point,) }
mesh = Mesh.from_file('box_girder.vtk')
domain = FEDomain('domain', mesh)
bounding_box = domain.get_mesh_bounding_box() min_y, max_y = bounding_box[:, 1] min_z, max_z = bounding_box[:, 2] eps_y = 1e-8 * (max_y - min_y) eps_z = 1e-8 * (max_z - min_z)
bearing = domain.create_region('bearing', 'vertices by get_bearing_point') # 梁端固定支座 bearing = domain.create_region('bearing', 'vertices in y < %.10f' % (min_y + eps_y), 'facet') deck = domain.create_region('deck', 'vertices in z > %.10f' % (max_z - eps_z), 'facet') # 梁顶面 girder = domain.create_region('girder', 'all')
field = Field.from_args('fu', np.float64, 'vector', girder, approx_order=2) u = FieldVariable('u', 'unknown', field) v = FieldVariable('v', 'test', field, primary_var_name='u')
m = Material('m', D=stiffness_from_youngpoisson(3, 3.5e10, 0.2)) f = Material('f', val=[[0], [0], [-23520]]) load = Material('load', function=pressure)
integral = Integral('ii', order=3)
t1 = Term.new('dw_lin_elastic(m.D, v, u)', integral, girder, m=m, v=v, u=u) # 弹性能积分项 t2 = Term.new('dw_volume_lvf(f.val, v)', integral, girder, f=f, v=v) # 体积力积分项 t3 = Term.new('dw_surface_ltr(load.val, v)', integral, deck, load=load, v=v) # 面力积分项
eq = Equation('balance', t1 - t2 - t3) eqs = Equations([eq])
fix_u = EssentialBC('fix_u', bearing, {'u.all': 0.0})
ls = ScipyDirect({}) nls_status = IndexedStruct() nls = Newton({'i_max': 1, 'eps_a': 1e-10}, lin_solver=ls, status=nls_status)
pb = Problem('elasticity', equations=eqs) pb.save_regions_as_groups('regions')
pb.set_bcs(ebcs=Conditions([fix_u])) pb.set_solver(nls)
status = IndexedStruct() vec = pb.solve(status=status)
print('Nonlinear solver status:\n', nls_status) print('Stationary solver status:\n', status)
pb.save_state('linear_elasticity.vtk', vec)
out = {}
stress = pb.evaluate('ev_cauchy_stress.ii.girder(m.D, u)', mode='evaluate')
out['cauchy_stress'] = Struct(name='output_data', mode='cell', data=stress, dofs=None)
Besides the above question, I wonder if there is any tutorial that shows how to write postprocess code interactively. I would greatly appreciate a full example from problem defining to postprocessing with coding style shown in this page Tutorial — SfePy version: 2023.1+git.fdee68c7 documentation.
By the way, the above problem was also subjected as issue#985 on GitHub. Evaluation failed · Issue #985 · sfepy/sfepy (github.com) I would greatly appreciate your support of any kind.