Hi all,
I am trying to solve the hyperelastic problem with adaptive meshes, and started with the Hyperelasticity demo. Here's the ufl file
# Function spaces
element = VectorElement("Lagrange", tetrahedron, 1)
# Trial and test functions
du = TrialFunction(element) # Incremental displacement
v = TestFunction(element) # Test function
# Functions
u = Coefficient(element) # Displacement from previous iteration
B = Coefficient(element) # Body force per unit volume
T = Coefficient(element) # Traction force on the boundary
# Kinematics
d = u.geometric_dimension()
I = Identity(d) # Identity tensor
F = I + grad(u) # Deformation gradient
C = F.T*F # Right Cauchy-Green tensor
# Invariants of deformation tensors
Ic = tr(C)
J = det(F)
# Elasticity parameters
mu = Constant(tetrahedron)
lmbda = Constant(tetrahedron)
# Stored strain energy density (compressible neo-Hookean model)
psi = (mu/2)*(Ic - 3) - mu*ln(J) + (lmbda/2)*(ln(J))**2
# Total potential energy
Pi = psi*dx - inner(B, u)*dx - inner(T, u)*ds
# First variation of Pi (directional derivative about u in the direction of v)
F = derivative(Pi, u, v)
# Compute Jacobian of F
J = derivative(F, u, du)
M=inner(u, u)*dx
I added
M=inner(u, u)*dx
as the Goal function for error estimation, following the undocumented demo auto-adaptive-navier-stokes. And compiled the form use:
ffc -l dolfin -e HyperElasticity.ufl
The output:
This is FFC, the FEniCS Form Compiler, version 1.6.0.
For further information, visit http://www.fenics.org/ffc/.
Traceback (most recent call last):
File "/usr/bin/ffc", line 213, in <module>
sys.exit(main(sys.argv[1:]))
File "/usr/bin/ffc", line 182, in main
parameters)
File "/usr/lib/python2.7/dist-packages/ffc/errorcontrol/errorcontrol.py", line 65, in compile_with_error_control
F, M, u = prepare_input_arguments(forms, object_names, reserved_objects)
File "/usr/lib/python2.7/dist-packages/ffc/errorcontrol/errorcontrol.py", line 156, in prepare_input_arguments
assert(len(arguments) == 2)
AssertionError
Any ideas? Cheers!
