Hi Manuel,
I am forwarding your message to the mailing list, because I could not reach you using your address (Connection timed out error). I will answer to the list as well.
r.
-------- Forwarded Message -------- Subject: SfePy - Electro-thermo-mechanics problem Date: Mon, 28 Aug 2017 12:31:33 +0200 From: Manuel Feuchter <manuel.feuchter@twt-gmbh.de> To: cimrman3@ntc.zcu.cz
Hey Robert,
first of all: SfePy is an amazing project! I am getting to like SfePy more and more :)
I tried to start a thread at https://mail.python.org/mm3/archives/list/sfepy@python.org But unfortunately am I not able to. I recieve a "Server Error (500)" . So I try it via Email :)
Concerning SfePy: I get stuck with a few problems/questions: Background: I would like to set up a subsequent coupled system (so not fully coupled): like to apply the electric field as an time (time step) dependent function.)
- electric field evolves an electric current (at the end of the day, I would
- electric current results in liberated heat by joule heating
- the liberated heat drives the thermal expansion und results in thermal stresses
1:
Concerning example: http://sfepy.org/doc-devel/examples/multi_physics/thermal_electric.html (multi_physics/thermal_electric.py) Equation: dw_laplace.2.Omega( m.electric_conductivity, psi, phi ) = 0 Your comment states: """ First solve the stationary electric conduction problem. Then use its results to solve the evolutionary heat conduction problem. """ Alright. However, just to understand it comprehensively? When you say you solve the "stationary electric conduction problem". Does this imply actually two equations? $(1) \textbf{E} = -\nabla \phi$\\ $(2) \textbf{j} = \frac{1}{\varrho}\cdot\textbf{E}$ Is this right?
# 2:
Assuming I got it right, I would like to solve the electric conduction problem in terms of a quasi-static circumstance (external electric potential and internal resistivity will change). This means I would like to solve the electric conduction problem for every time step that I run the simulation and hence use the result (of $\textbf{j}$) for every next time step. I tried so, however I must have gotten sth wrong. The apparent electric field is not used?! Am I right? And how am I able to achieve so? (please find my code below)
# 3:
For the heat conduction equation: ... = dw_electric_source.2.Omega( m.electric_conductivity, s, phi ) Here, for the source term $\textbf{p} = \varrho \cdot \textbf{j}^2$ is solved? And how does the specific heat gets involved in your equation? Is the source term divided by the thermal conductivity [W/mK]? Does specific_heat to be named exactly like this to be involved in the 'dw_volume_dot.2.Omega( s, dT/dt )' term?
# 4:
How am I able to apply a time (time step) dependent function for the electric potential?!
Looking forward for your reply! Cheers and kind regards from Germany Manuel
def stress_strain_ext(out, pb, state, extend=False): """ Calculate and output strain and stress for given displacements. """ from sfepy.base.base import Struct from sfepy.mechanics import tensors
ev = pb.evaluate
strain = ev('ev_cauchy_strain.2.Omega(u)', mode='el_avg')
stress = ev('ev_cauchy_stress.2.Omega(m.mech_solid, u)', mode='el_avg')
vms = tensors.get_von_mises_stress(stress.squeeze())
vms.shape = (vms.shape[0], 1, 1, 1)
out['cauchy_strain'] = Struct(name='output_data', mode='cell',
data=strain, dofs=None)
out['cauchy_stress'] = Struct(name='output_data', mode='cell',
data=stress, dofs=None)
out['von_mises_stress'] = Struct(name='output_data', mode='cell',
data=vms, dofs=None)
return out#! Presettings #! ------- t0 = 0.0 t1 = 100.0 n_step = 11 # material parameters and constants lam = 10.0 mu = 5.0 thermal_expandability = 1.25e-5 T0 = 20.0 # Background temperature. specific_heat = 1.2 thermal_kappa_xyz = 2.0 electric_sigma_xyz = 1.5
#! Options #! ------- options = { 'ts': 'ts', 'nls': 'newton', 'ls': 'ls', 'output_dir' : output_dir, 'post_process_hook' : 'stress_strain_ext', }
#! Regions #! ------- regions = { 'Omega': 'all', 'Omega_Cell_Surface': ('vertices of surface', 'facet'), 'Mech_Mount': ('vertices in (x < 0.05)', 'facet'), 'Mech_Front': ('vertices in (x > 0.95)', 'facet'), 'Therm_inlet': ('vertices in (x < 90.05) & (x > 85.95) & (y > 9.95)', 'facet'), 'Therm_outlet': ('vertices in (x < 0.05)', 'facet'), 'Elec_Phi_0' : ('vertices in (x < 37.05) & (x > 32.95) & (y > 9.95)', 'facet'), 'Elec_Phi_1' : ('vertices in (x < 90.05) & (x > 85.95) & (y < 0.05)', 'facet'), }
#! Materials #! --------- eye_sym = np.array([[1], [1], [1], [0], [0], [0]], dtype=np.float64) materials = { 'm': ({ 'thermal_conductivity': thermal_kappa_xyz, 'electric_conductivity': electric_sigma_xyz, 'mech_solid' : stiffness_from_lame(3, lam=lam, mu=mu), 'alpha_therm' : (3.0 * lam + 2.0 * mu) * thermal_expandability * eye_sym },), 'mech_load': ({'.val': [0.0, 0.0, 0.0]},), }
#! Fields #! ------ fields = { 'displacement': ('real', 'vector', 'Omega', 1), 'temperature': ('real', 1, 'Omega', 1), 'potential' : ('real', 1, 'Omega', 1), }
#! Variables #! --------- variables = { 'u': ('unknown field', 'displacement', 2), 'v': ('test field', 'displacement', 'u'), 'T': ('unknown field', 'temperature', 0, 1), # 1 means, set history "on" 's': ('test field', 'temperature', 'T'), 'phi': ('unknown field', 'potential', 1, 1), 'psi': ('test field', 'potential', 'phi'), }
#! Initial Conditions #! ------------------- ics = { 'ic' : ('Omega', {'u.all' : 0.0, 'T.0': 0.0, 'phi.all': 0.0, }), }
#! Boundary Conditions #! ------------------- ebcs = { 'u0': ('Mech_Mount', {'u.all': 0.0}), 't0': ('Mech_Mount', {'T.0': 0.0}), 't1': ('Mech_Front', {'T.0': 0.0}), 'p0' : ('Elec_Phi_0', {'phi.0' : 0.0}), 'p1' : ('Elec_Phi_1', {'phi.0' : 100.0}), }
#! Equations #! --------- equations = { 'potential' : """dw_laplace.2.Omega( m.electric_conductivity, psi, phi ) = 0""", 'heat_conduct' : """dw_volume_dot.2.Omega( s, dT/dt ) + dw_laplace.2.Omega( m.thermal_conductivity, s, T ) = dw_electric_source.2.Omega( m.electric_conductivity, s, phi )""", 'thermo_mech': """dw_lin_elastic.2.Omega(m.mech_solid, v, u) - dw_biot.2.Omega(m.alpha_therm, v, T) = 0""", }
#! Solvers #! ------- solvers = { 'ls' : ('ls.scipy_direct', {}), 'newton' : ('nls.newton', { 'i_max' : 1, 'eps_a' : 1e-10, 'eps_r' : 1.0, 'problem': 'nonlinear', }), 'ts': ('ts.simple', { 't0': t0, 't1': t1, 'dt': None, 'n_step': n_step, }), }
Schöne Grüße kind regards
i.A. Manuel Feuchter Competence Unit Engineering
Dr.-Ing. Manuel Feuchter Head of Multibody & Structure Analysis
TWT GmbH - Science & Innovation Ernsthaldenstraße 17 D-70565 Stuttgart E-Mail: manuel.feuchter@twt-gmbh.de Mobil: +49 162 / 212 48 16