Hello everyone,

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)

def eps(u):

return sym(grad(u))

def sigma_0(u):

mu = E/(2.0*(1.0 + nu))

lmbda = E*nu/(1.0 - nu**2)
return 2.0*mu*(eps(u)) + lmbda*tr(eps(u))*Identity(ndim)

Could someone please, please help me?