A CAD Model for the Tolerancing of Non-rigid Parts Assemblies

Abstract

The study of the mechanical assembly behavior during the design stage requires the modeling of components with manufacturing defects. However, the integration of tolerances in the CAD model, only with geometrical and dimensional errors without taking into account several factors such as the deformations of parts during the assembly task, generates an important difference between the digital and the real models. Thus, a new model for the tolerancing of assemblies in CAD is developed considering the deformations of parts under loads. The realistic assembly configurations are obtained basing on the parts with defects. The dimensional and geometrical defects of parts are represented in the CAD modeler basing on the worst-case tolerancing approach and the Small Displacement Torsor (SDT) parameters. The Finite Elements (FE) computation is executed with realistic part models. Sub-algorithms are developed to update the mechanical joints between couples of Non-Rigid/Non-Rigid (NR/NR) components. The tolerance analysis is performed basing on the obtained realistic assembly. A case study is used to show the highlights of the proposed method.