An integrated open source CAT based on Skin Model Shapes

The control of geometrical deviations and form variations throughout the product life-cycle is a fundamental task in geometric dimensioning and tolerancing. As product complexity increases, it has not only become necessary to rely on computers to process geometrical and non-geometrical information from early design stages but also to come up with more realistic shape representation. Most of computer-aided tolerancing (CAT) packages used nowadays are fully integrated to computer-aided design softwares like CATIA and SolidWorks and they allow to model 2D and 3D tolerances stack-up through worst-case or statistical models. These CAT systems are generally available as proprietary commercial software which can sometimes restrict their domain of application and slow the implementation of new paradigms like the Skin Model. The Skin Model is an abstract surface model that represents the interface between a workpiece and its environment whose implementation involves the modeling of finite instances of the Skin Model called Skin Model Shapes (SMS) that encompass different sources of deviations and constitute a non-ideal geometrical model. The aim of this work is to show the first phase of implementation of an integrated open source environment based on PolitoCAT and Salome to model Skin Model Shapes. An Unified Model Language (UML) based logical data model of the integrated system is presented, it is an extended version of current data models for geometric modeling that includes the objects and relationships to manage form variations at different design stages. The work carried out contributes to the conceptualization of Skin Model Shapes model and it constitutes a support on the implementation of SMS in an open source CAT. An example of this integration involving a Skin Model Shapes implementation is shown as an illustration of the functionality of the platform.