Boundary conditions

Abstract

No FEM solution is possible without defining the behaviour/conditions of the nodes at the boundaries of the virtual domain, the so-called boundary conditions of the FEM model. Therefore, the solution of any FEM problem is highly dependent on the boundary conditions implemented. This chapter explores this extremely important feature of an FEM model. Although loads and boundary conditions are distinguished in certain FEM solvers, such as ABAQUS, the presentation here considers both of them under the broad description of boundary conditions. This chapter introduces the different types of boundary conditions commonly in use in many FEM solvers. Special attention is given to periodic boundary conditions since it has been shown in literature that they can quickly arrive at the convergent solution of an FEM problem. A methodology for imposing this type of boundary condition for a 2D representative volume element (RVE) is shown too. The ability to define correctly an appropriate boundary condition for a given problem is a vital skill for anyone who wants to use the FEM process to determine reliable solutions of any physical problem.