The Modeling DilemmaFor complex components there are a multitude of fillets that represent potential crack initiation points.

Procedure for the submodel methodTo solve the issue outlined before the solution is to chose an average mesh density so that the structure's areas that are subject to large stresses can in fact be detected, however – due to the rough mesh size - stresses sometimes can deviate up to a factor of 2 (even more in the case of sharp notches) from the exact values. It is important to keep in mind that the component's displacement distribution is described very accurately by these models already while the finite elements are not able to provide accurate stresses at the same time. This is basically due to the fact that stresses have to be calculated based on the derivatives of displacements.

The "trick" when using the submodel method is to generate new, finer finite element meshes for critical component subareas and to subject them again to a FEM analysis with the given displacement boundary conditions of the overall model.

Notch stresses depending on the mesh density