Framework for a Structure Oriented Exchange of CAD Data

Table of Contents

I. Introduction

1. Problem analysis and requirements definition

2. Review state of the art of exchange strategies

3. Analysis of modelling capabilities regarding feature modelling and structure representation

4. Needs-identification

5. Requirement definitions

6. Outline of the thesis

II. Approaches to the Exchange of CAD Data

1. Outline

2. General Classification of Exchange Approaches

2.1. Direct and Standard-based exchange Approaches

2.2. Horizontal and Vertical Exchange Approaches

2.3. Classification of exchange strategies

3. Capabilities of Scientific Exchange Strategies

3.1. On the Implicit Exchange of Feature-Based Product Model Data

3.2. Exchange of CAD Part Models Based on the Macro-Parametric Approach

3.3. The Unified Approach to Modelling Multidisciplinary Interaction

3.4. An exchange Approach in Conceptual-Based Design System

3.5. Open CAD Environment

4. Capabilities of Exchange Strategies in Commercial Areas

4.1. Vendor Exchange Method

4.2. Native Exchange Method

4.3. Neutral Exchange Method

4.3.1. IGES

4.3.2. VDA-FS

4.3.3. SET

4.3.4. XBF

4.3.5. PDDI

4.3.6. Projects Related to Neutral Exchange Methods

4.3.7. STEP (ISO-10303)

5. Further technologies

5.1. Parts Library

5.2. CAD – Services

5.3. ProSTEP

6. Conclusion

III. Analysis of today’s CAD systems – concepts and capabilities

1. Outline

2. Feature modelling definitions

2.1. Feature definitions

2.2. Feature model definition

2.3. Feature modelling definition

2.4. Feature attributes definition

2.5. Types of features

2.6. Feature properties

2.7. Feature properties classification

2.8. Generic and composite features

2.9. Feature taxonomies

2.10. Feature mapping

3. Analysis of feature modeling methods

3.1. Basic feature creation methods

3.2. Analysis of specific features modeling methods

3.2.1. Interactive feature modeling

3.2.2. Automatic (recognition) feature recognition

3.2.3. Design by feature modeling

3.3. Analysis of structural representation regarding feature modeling methods

3.3.1. Automatic feature recognition

3.3.2. Design by feature modelling

4. Major benefits of feature modelling methods

4.1. Design Intent

4.2. Multilevel structure

4.3. Feature-Kernel

5. Deficiencies as a result of feature data exchange

6. Analysis of commercial systems

6.1. Scope and process of analysis

6.1.1. Analysis of basic feature creation methods

6.1.2. Analysis of modelling kernel

6.1.3. Scope and process of model representation

6.2. Pro/Engineer’s analysis

6.3. I-DEAS’s analysis

6.4. Unigraphic’s analysis

7. Conclusions

IV. Exchange strategy – concept

1. Problem discussion

2. Needs identification on a Feature Model-Tree exchange methodology

3. Requirements definition - sequence of needs identification

3.1. Openness - neutral type of exchange data

3.2. Modularity – structure oriented data

3.3. Optimal Completeness – optimal density of exchange data

4. Requirements list

5. Established and new exchange strategies

6. Concept details

6.1. Fundamental ideas

6.2. General framework

6.3. Detail of the framework

6.4. Translation process

V. Evaluation and outlook

Objectives and Research Themes

The thesis aims to address the challenge of data loss during the exchange of CAD models between different systems, specifically focusing on the loss of "model tree" (design intent) and feature information. It investigates existing scientific and commercial exchange strategies, analyzes feature modelling capabilities in leading CAD software (Pro/Engineer, I-DEAS, Unigraphics), and develops a conceptual framework for a structure-oriented exchange of CAD model data to preserve this critical design information throughout the product life cycle.

• Analysis of CAD feature modelling and structural representation techniques.
• Evaluation of current scientific and commercial data exchange methodologies (e.g., IGES, STEP).
• Comparative analysis of how major commercial CAD systems handle feature and model representation.
• Identification of requirements for preserving model-tree integrity during data transfer.
• Proposal of a new conceptual framework for structure-oriented CAD data exchange.

Excerpt from the Book

Summary of Chapters

I. Introduction: This chapter establishes the problem statement regarding the loss of design intent during CAD data exchange and outlines the goals and structure of the thesis.

II. Approaches to the Exchange of CAD Data: This section reviews state-of-the-art scientific and commercial data exchange strategies, covering direct, standard-based, horizontal, and vertical exchange methods.

III. Analysis of today’s CAD systems – concepts and capabilities: The author examines fundamental feature modelling concepts and evaluates three specific commercial CAD systems (Pro/Engineer, I-DEAS, Unigraphics) based on their modelling kernels and representation structures.

IV. Exchange strategy – concept: This chapter defines the requirements for a structure-oriented exchange and presents a proposed conceptual framework for preserving model trees.

V. Evaluation and outlook: The author concludes by assessing the feasibility of the proposed concept and identifying areas for future development regarding the full exchange of feature model trees.

Keywords

CAD, Data Exchange, Feature Modelling, Design Intent, Model Tree, Engineering Product Data Exchange, STEP, IGES, Structural Representation, Feature Library, Implicit Exchange, Macro-Parametric Approach, CAD Systems, Product Life Cycle, Interoperability

Frequently Asked Questions

What is the primary focus of this thesis?

The work focuses on developing a methodology for the "structure-oriented exchange" of CAD data, aiming to minimize the loss of design intent and feature-related information when transferring models between different CAx systems.

What are the central thematic areas?

The core themes include CAD system interoperability, feature modelling taxonomies and methods, structural data representation, and the critical analysis of existing exchange standards and scientific strategies.

What is the main research objective?

The primary goal is to specify an overall framework that allows the exchange of "model trees" and design intent, thereby enabling users to modify exchanged CAD models at the feature level in receiving systems.

Which scientific methods are employed?

The thesis utilizes a literature review of existing exchange strategies followed by a deep-dive comparative analysis of three major commercial CAD systems (Pro/Engineer, I-DEAS, and Unigraphics) to identify their underlying modelling kernels and feature creation logic.

What does the main body cover?

The main body systematically reviews exchange technologies, provides a detailed classification of feature modelling, conducts a hands-on technical analysis of selected commercial CAD software, and derives specific requirements for a new, more robust exchange framework.

Which keywords characterize the work?

Essential keywords include CAD, Data Exchange, Feature Modelling, Design Intent, Model Tree, Engineering Product Data Exchange, STEP, IGES, Structural Representation, and Interoperability.

Why do exchanged CAD models often lose their features?

According to the author, models lose features because existing exchange formats often focus on static geometry rather than the design history (the "model tree") or the specific "design intent" and procedural logic used by the original CAD system.

What role does the "Model Tree" play in this research?

The model tree is identified as the key component that captures the design sequence and structural relationships; its loss is defined as a primary failure of current data exchange, and the research specifically aims to enable its transfer.