The aim of the submodel is to reduce the deviations from the whole finite element analysis.
When we obtain the stress and strain state of the whole component, the mesh used may not have a suitable size due to the volume of the whole component.
For this reason a submodel is made over the part most susceptible to suffering fatigue. Now we can use a suitable mesh because the computational limitations are reduced. In the submodel limits, boundary conditions from the whole system analysis are introduced and it is possible to determine, with great accuracy, the stress and strain state of the critical zone.
This stage is very important in order to get good correlation with the experimental tests.