High Order Mixed Finite Elements with Mass Lumping for Elasticity on Triangular Grids

Abstract

A family of conforming mixed finite elements with mass lumping on triangular grids are presented for linear elasticity. The stress field is approximated by symmetric $H($div) − $P_k (k ≥ 3)$ polynomial tensors enriched with higher order bubbles so as to allow mass lumping, and the displacement field is approximated by $C^{−1}− P_{k−1}$ polynomial vectors enriched with higher order terms. For both the proposed mixed elements and their mass lumping schemes, optimal error estimates are derived for the stress and displacement in $H$(div) norm and $L^2$ norm, respectively. Numerical results confirm the theoretical analysis.