A Stabilized Low Order Finite Element Method for Three Dimensional Elasticity Problems

Abstract

We introduce a low order finite element method for three dimensional elasticity problems. We extend Kouhia-Stenberg element [12] by using two nonconforming components and one conforming component, adding stabilizing terms on the associated bilinear form to ensure the discrete Korn's inequality. Using the second Strang's lemma, we show that our scheme has optimal convergence rates in L-2 and piecewise H-1-norms even when Poisson ratio nu approaches 1/2. Even though some efforts have been made to design a low order method for three dimensional problems in [11, 16], their method uses some higher degree basis functions. Our scheme is the first true low order method. We provide three numerical examples which support our analysis. We compute two examples having analytic solutions. We observe the optimal L-2 and H-1 errors for many different choice of Poisson ratios including the nearly incompressible cases. In the last example, we simulate the driven cavity problem. Our scheme shows non-locking phenomena for the driven cavity problems also.