Parametric CAD modeling: An analysis of strategies for design reusability

Abstract

CAD model quality in parametric design scenarios largely determines the level of flexibility and adaptability of a 3D model (how easy it is to alter the geometry) as well as its reusability (the ability to use existing geometry in other contexts and applications). In the context of mechanical CAD systems, the nature of the feature-based parametric modeling paradigm, which is based on parent-child interdependencies between features, allows a wide selection of approaches for creating a specific model. Despite the virtually unlimited range of possible strategies for modeling a part, only a small number of them can guarantee an appropriate internal structure which results in a truly reusable CAD model. In this paper, we present an analysis of formal CAD modeling strategies and best practices for history-based parametric design: Delphi's horizontal modeling, explicit reference modeling, and resilient modeling. Aspects considered in our study include the rationale to avoid the creation of unnecessary feature interdependencies, the sequence and selection criteria for those features, and the effects of parent/child relations on model alteration. We provide a comparative evaluation of these strategies in the form of a series of experiments using three industrial CAD models with different levels of complexity. We analyze the internal structure of the models and compare their robustness and flexibility when the geometry is modified. The results reveal significant advantages of formal modeling methodologies, particularly resilient techniques, over non-structured approaches as well as the unexpected problems of the horizontal strategy in numerous modeling situations.

Revisiting the design intent concept in the context of mechanical CAD education

“…"Horizontal" modeling minimizes CAD repair by removing parent/child dependencies between features, " Explicit References" modeling minimizes the number of constraints linked to existing geometries by managing functional references, and "Resilient" modeling manages the sequence of the design tree by organizing the features by purpose and priority [12]. The researchers found that "Resilient" modeling was most effective, although the level of CAD expertise of the study population (students) could have affected the results [12].…”

“…We believe that suggestions on how design intent can be enhanced and captured can be arranged into three categories: (1) basic strategies that have been previously suggested by different authors and are generally followed by CAD instructors; (2) strategies that are linked to metrics that can be automated by Model Quality Testers, which rarely include highly semantic quality concepts like those linked to design intent (see for example: [12]), and (3) novel strategies that currently appear in the scientific literature, but remain absent from most of the instruction courses (see [13], [12]). …”

“…In a more detailed examination, these different modeling methodologies were studied to examine CAD reusability [12]. "Horizontal" modeling minimizes CAD repair by removing parent/child dependencies between features, " Explicit References" modeling minimizes the number of constraints linked to existing geometries by managing functional references, and "Resilient" modeling manages the sequence of the design tree by organizing the features by purpose and priority [12].…”

A Contribution to Conveying Quality Criteria in Mechanical CAD Models and Assemblies through Rubrics and Comprehensive Design Intent Quantification

“…They further state that "Explicit References" modeling provides for simple models but are difficult to model and "Resilient" modeling is effective, in spite of reference nodes needed to reduce dependencies [Camba et al, 2014a]. In a more detailed examination, these different modeling methodologies were studied to examine CAD reusability [Camba et al, 2016]. "Horizontal" modeling minimizes CAD repair by removing parent/child dependencies between features, " Explicit References" modeling minimizes the number of constraints linked to existing geometries by managing functional references, and "Resilient" modeling manages the sequence of the design tree by organizing the features by purpose and priority [Camba et al, 2016].…”

“…In a more detailed examination, these different modeling methodologies were studied to examine CAD reusability [Camba et al, 2016]. "Horizontal" modeling minimizes CAD repair by removing parent/child dependencies between features, " Explicit References" modeling minimizes the number of constraints linked to existing geometries by managing functional references, and "Resilient" modeling manages the sequence of the design tree by organizing the features by purpose and priority [Camba et al, 2016]. The researchers found that "Resilient" modeling was most effective, although the level of CAD expertise of the study population (students) could have affected the results [Camba et al, 2016].…”