Summary of results
======================

Residual error estimator ERRE_ELEM_SIGM gives good results on bi-material problems.

**Note:**

*The Zhu-Zienkiewicz error estimator does not give correct results. Indeed, at the interface it detects a strong error because it performs a continuous smoothing of the constraints while there is a jump for* :math:`{\sigma }_{\mathrm{zz}}` *and* :math:`{\sigma }_{\theta \theta }` *.*