Conforming Mixed Triangular Prism Elements for the Linear Elasticity Problem

Abstract

We propose a family of conforming mixed triangular prism finite elements for solving the classical Hellinger-Reissner mixed problem of the linear elasticity equations in three dimensions. These elements are constructed by product of elements on triangular meshes and elements in one dimension. The well-posedness is established for all elements with $k ≥ 1$, which are of $k+1$ order convergence for both the stress and displacement. Besides, a family of reduced stress spaces is proposed by dropping the degrees of polynomial functions associated with faces. As a result, the lowest order conforming mixed triangular prism element has 93 plus 33 degrees of freedom on each element.