A New Method for Tolerance Integration in CAD Model

In the Digital Mock-Up (DMU), the parts and the assemblies are used in the nominal configurations. In fact, the tolerances are formally represented in CAD model and the impacts of tolerance stack-up are not considered during the optimization of the mechanical system assemblability and the F.E. Analysis. Then, the improvement of the numerical model requires the tolerance consideration in the CAD model. This paper presents an approach to incorporate dimensional and geometrical tolerances in CAD model. The models to obtain worst case components are developed. The worst case assemblies can be obtained by performing various combinations between the components in worst case configurations. Nevertheless, the regeneration of the worst case assemblies, composed by the realistic components, requires redefining assembly mating constraints which are initially allocated to the nominal assembly. Thus, in the case of rigid body, a new approach to update the mating constraints of a realistic assembly is presented. Keywords— CAD model, mating constraint, dimensional tolerance, geometrical tolerance, realistic model.