Application of the Hybrid-Mixed Finite Element Method with Stabilized Nodal Enrichment on 2D Problem
This work addresses the development of non-conventional variants of the finite element method for plane elasticity based on the combination of the Stable Generalized Finite Element Method (SGFEM) with Hybrid-Mixed Stress Formulation (HMSF). For the HMSF three approximation fields are involved: stresses and displacement in the domain and displacement on the static boundary. In the combined HMSF-SGFEM approach the enrichment of the stress domain field is provided by the product of the Partition of Unity (PoU) and polynomials enrichment functions. It is noteworthy that the nodal enrichment structure in SGFEM is different from that applied in Generalized Finite Element Method (GFEM). In addition, the resource of the so-called nodal enrichment available by SGFEM and GFEM conceptually enlarges the approximation bases of the HMSF, without the need to introduce new nodal points in the domain. The simulations of 2D elasticity problem were developed applying a plane four node quadrilateral element of the HMSF-SGFEM. The numerical simulation of HMSF-SGFEM was implemented using FORTRAN® routines. The performance of this new approach (HMSF-SGFEM) is illustrated and compared with classical Finite Element Method (FEM). The results, in terms of strain energy and stress field, obtained from the application of this new methodology, HMSF-SGFEM, point to the quality of this unconventional methodology presented, once the enrichment of the stress field did not destroy strain energy results and improved the stress field. Lastly, the application of nodal enrichment in problems with coarse meshes allowed obtaining results comparable to those obtained through the same problem but with more refined mesh and without enrichment.