### Minimum Constraints in FEA – 5. Submodeling by Kotur Raghavan

General Submodeling is a technique usually adopted in order to fine-tune the stress results at critical locations. One conducts local analysis with refined mesh by imposing the boundary conditions from the full or global model. Deformations from the full (coarse) model are interpolated with the help of element shape functions. This is the conventional approach and is based on Saint-Venant’s principle. This can be called as Cut-Boundary-Displacement (CBD) approach. The approach is well established and promotes productivity enhancements as the need to refine the mesh in the entire structure is eliminated. However, there are two limitations. The first one is that the geometry should be identically similar in the global and the submodel. If there is any change in stiffness the computed stresses will be in error. In addition, it is valid strictly for linear analysis. The above limitations can be overcome by resorting to one of the two variants. The first alternative is based on impos