The program below function well.
If I replace, in the expression of the constraint (last line), the trace of the deformation tr(eps (u) by its absolute value abs(tr(eps (u));
The code does not work anymore.
Could someone please help me?
nu = Constant(0.3)
mu = E/(2.0*(1.0 + nu))
lmbda = Enu/(1.0 - nu**2)
return 2.0mu*(eps(u)) + lmbda*tr(eps(u))*Identity(ndim)
Could someone please, please help me?