Adding a tensor to a constant tensor, creating a 4-tensor from two 2-tensors and contracting tensors

[dokken]

@oszachter

def A(q):
    g0=fem.Constant(domain, ScalarType((((1,0)), (0,1))))
    gbar=g0+q
    A=np.zeros((2,2,2,2))
    for i in range (2):
      for j in range (2):
        for k in range (2):
          for k in range(2):
            A[i,j,k,l]=nu(Y/(1-nu**2))*(gbar[i,j]*gbar[k,l]+(1-nu)/(2*nu)(gbar[i,k]*gbar[j,l]+gbar[i,l]*gbar[j,k]))
    return as_tensor(A)

You are mixing numpy and ufl.
A should be a ufl tensor; see for instance Slicing Tensors using subset of Free Indices or multiple free indices - #2 by dokken