Identifying and Quantifying Functional Elements Dispersions During Functional Analysis

Abstract

This paper presents a methodology for supporting the designer during one of the most important stages of mechanical design: functional analysis. The mechanism to be analysed is first represented in a Functional Element Graph. The designer must then identify some Functional Requirements between elements in this graph, typically in the form of critical toleranced dimensions or toleranced gaps. For each such Functional Requirement, a systematic graph growing algorithmic engine then traverses the Functional Element Graph in order to build a subgraph consisting of candidate Functional Element pairs possibly affecting the Functional Requirement. For each Functional Element pair identified in the process, a list of its possible dispersions is established through an associative table. Once the dispersions have been identified, a set of simple rules is finally used to quantify each dispersion and translate it into a possible dimensional or geometric tolerance interval on the corresponding Functional Element pairs. An example is used throughout the paper to illustrate the proposed approach.