Hello, I am trying to model the elasticity problem with two field function spaces(displacements ans stresses). the function spaces are assumed as below:
V1=VectorElement(“CG”, mesh.ufl_cell(), 2) # displacements
V2=FiniteElement(“CG”, mesh.ufl_cell(), 1) # Stresses
MX = FunctionSpace(mesh,MixedElement([V1,V2]))
(u,sigma)= TrialFunctions(MX)
(del_u,del_sigma) = TestFunctions(MX)
i,j,k,l= indices(4)
and strain field is:
def Strain(u):
return as_tensor((1./2.*(u[i].dx(j)+u[j].dx(i))),[i,j])
when I trying to solve the variational equations I receive the following error:
UFLException: Attempting to index with (Index(8), Index(9)), but object is already indexed
but when I replace the FiniteElement with TensorElement the problem is solved but the results are not correct and the same results obtained for both displacement and stress fields!