A hierarchical set of SysML Model-based objects for tolerance specification

Modern engineering systems are getting complex and integrate multi-physical objects. The Model-Based System Engineering (MBSE) seems to be the best way to manage complex system design and the Systems Modeling Language (SysML) may be considered one of the computer languages to perform the designing of a complex system. MBSE also seems to be a valid solution to integrate tolerance specification into design process. In particular, in the present work SysML is used to create a set of libraries containing simple and complex volumes, primary datum and tolerance zones, according to ASME Y14.5M and ISO 1101 standards. The generation of these libraries is based on the Technologically and Topologically Related Surfaces (TTRS) model and uses the set of thirteen positioning constraints able to represent every condition between assembly features. The paper summarizes the characteristics of the created SysML objects, able to represent Datum, Datum Reference Frame (DRF) and tolerance zones. In particular, the Datum included in ASME Y14.5-M are modelled. Then, all the tolerance zones included in both standards are modelled. Finally, a three-step procedure is summarized to preliminary illustrate the way of use the developed set of SysML objects.