A robust a posteriori error estimate for the Fortin-Soulie finite-element method

The subject of a posteriori error estimation is widely studied, and a variety of such error estimates have been used for elasticity problems in recent years. Of particular interest is the work carried out in 1. and 2.. In this paper, we derive a new a posteriori error estimator for the quadratic nonconforming Fortin-Soulie element for the error in an energy-like norm. Then, we illustrate the new error bound by presenting some numerical examples, and show an example of a sequence of adaptively refined meshes.