The Arnold–Winther mixed FEM in linear elasticity. Part I: Implementation and numerical verification

Following some de Rham complex, Arnold and Winther have recently proposed a symmetric mixed finite element method (MFEM) in linear elasticity. This paper describes the implementation of the symmetric MFEM and its 30 × 30 local stress stiffness matrices and studies the implementation of the lowest-order scheme for general boundary conditions. Numerical experiments in model examples in computational mechanics illustrate the robust locking-free convergence behavior and support the theoretically predicted experimental convergence rates.