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CAD-Model Parsing for Automated Design and Design Evaluation
Jönköping University, School of Engineering, JTH. Research area Computer Supported Engineering Design.
2008 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Product development has both innovative and analytic sides. Starting from the requirements, a design suggestion is generated. In order to assess how well the envisioned design fulfils the requirements, it is sometimes necessary to build a computer model of it for the analysis. The overall motivation of the work presented is to reduce the time spent on creating the model by reusing knowledge gained from developing similar products by suggesting, building and evaluating IT-systems. To verify the systems real design examples, obtained from companies that have participated in the research projects have been used.

The work is based on two major application examples. The first, involving the automated geometrical idealisation of die-cast parts (Paper I-III), and the second involving manufacturability of powder metallurgy pressed and sintered parts (Paper IV-VI). The work starts from the point in the product development process where it exists a design suggestion represented as an arbitrary format CAD-model. In the powder metallurgy case the object is to secure that the geometry is suitable for the production process. In the die-casting case the object is to automatically create an idealised version of the model for shell elements meshing. These two tasks have previously been treated as two separate cases, addressed by completely different software. This thesis suggests a common method for addressing the two cases. The method is based on converting the CAD-models, using the geometrical restrictions of the production processes, into a format with a specialised feature structure, parameterisation and construction history using a feature recognition approach. The features are then automatically reconstructed in a target CAD-system. The resulting, specialised CAD-model can be used for automated design and design evaluation purposes, demonstrated in the thesis. The models are therefore called DAR (Design Automation Ready)-models. The DAR-models are useful in that they separate the conversion from the subsequent treatment of the models providing modularisation, flexibility and user insight in the model structure. In that a construction history and parameterisation have be constructed in the target CAD-system, the advanced geometry manipulation and means for knowledge management often provided in modern CAD-systems can be accessed in a transparent and user manageable way. This extends the usefulness of the CAD-systems from involving only interactive work to managing all components sharing the same production process.

Place, publisher, year, edition, pages
Göteborg: Chalmers Reproservice , 2008. , p. 162
Series
Doktorsavhandlingar vid Chalmers Tekniska Högskola, ISSN 0346-718X ; 2856
Keywords [en]
Design automation, CAD, KBE, Feature based modelling, Feature recognition, Product development.
National Category
Production Engineering, Human Work Science and Ergonomics
Identifiers
URN: urn:nbn:se:hj:diva-10700ISBN: 978-91-7385-175-6 (print)OAI: oai:DiVA.org:hj-10700DiVA, id: diva2:273437
Public defence
2008-12-11, E1405, Tekniska Högskolan i Jönköping, Gjuterigatan 6, 551 11 Jönköping, Jönköping, 10:00 (English)
Opponent
Supervisors
Note
Teknologie DoktorsexamenAvailable from: 2009-11-03 Created: 2009-10-21 Last updated: 2009-11-03Bibliographically approved
List of papers
1. Identifying Features in Cad-Models for Powder Metallurgy Component Evaluation
Open this publication in new window or tab >>Identifying Features in Cad-Models for Powder Metallurgy Component Evaluation
2008 (English)In: Proceedings of the Design 2008, 10th International Design Conference, 2008, p. 689-696Conference paper, Published paper (Refereed)
Abstract [en]

This paper presents a newly developed CAD-integrated system for the manufacturability evaluation of designs of powder metallurgy (PM) pressed and sintered parts. The contribution of the paper is the automated reconstruction of a specialized construction history tree from any CAD-model directly in the receiving CAD-system. The reconstruction is based on the geometrical restrictions of the shapes that can be manufactured by the PM process. This facilitates the creation of a transparent and user-revisable rule-base to evaluate the parts manufacturability, which is shown. It will enable designers to get feedback on their designs, reducing the number of design loops with the PM-parts supplier needed before the parts geometry can be established.

Keywords
Feature, CAD, Rule, Powder Metallurgy
National Category
Materials Engineering
Identifiers
urn:nbn:se:hj:diva-1641 (URN)978-953-6313-89-1 (ISBN)
Available from: 2008-09-29 Created: 2008-09-29 Last updated: 2010-01-08Bibliographically approved
2. An Automated Design and Advisory System for Pressed-and-Sintered Powder Metallurgy Parts
Open this publication in new window or tab >>An Automated Design and Advisory System for Pressed-and-Sintered Powder Metallurgy Parts
2008 (English)In: Proceedings of the 2008 World Congress on Powder Metallurgy & Particulate Materials, June 8–12, Washington, D.C. United States, Princeton, NJ, United States: MPIF , 2008Conference paper, Published paper (Refereed)
Abstract [en]

The aim of the present paper is to dissolve the bottleneck for PM market expansion caused by lack of knowledge among designers about PM-specific design principles by proposing an automated PM-part advisory system. The system, called PM-Wizard, checks that a PM-part design suggestion represented as any 3D solid CAD-model complies with the geometrical design rules and recommendations for PM-parts. The system consists of a rule-base hosted by a modern commercial CAD/CAE-system and a programmed algorithmic procedure that converts the design suggestion into a specially developed format. The format enables the automated evaluation of the PM-part in the receiving CAD/CAE-system informing the designer on how the geometry should be revised to facilitate the pressing. The conversion algorithm has been tested on a large number of PM-parts, and the result is that all the tested parts can be converted into the proposed format and successfully evaluated.

Place, publisher, year, edition, pages
Princeton, NJ, United States: MPIF, 2008
Keywords
Powder Metallurgy, Advisory system, Knowledge-based Engineering
National Category
Materials Engineering
Identifiers
urn:nbn:se:hj:diva-6558 (URN)0-9793488-9-7 (ISBN)
Available from: 2008-10-16 Created: 2008-10-16 Last updated: 2009-02-16Bibliographically approved
3. Reusing CAD-models of Die-cast products for FEA
Open this publication in new window or tab >>Reusing CAD-models of Die-cast products for FEA
2006 (English)In: NAFEMS Seminar: Prediction and Modelling of Failure Using FEA, 2006Conference paper, Published paper (Refereed)
Abstract [en]

Parts for trimmers, lawnmowers and chainsaws are often manufactured by die-casting in light alloys. These parts often have a complex geometry with thin-walled regions mixed with regions of non thin-walled geometry. This paper discusses the process of creating FEA-models from CAD-models of such parts. The objective of the FEA, in the particular case described in this paper, is to predict the performance of the complete products. Since a FEA-model of the complete product require extensive computational power to solve, it is necessary to keep the computational cost down by f. ex using shell-elements instead of solid-elements where applicable.

The creation of the shell-element mesh based on the solid CAD-model can be time consuming, especially if the CAD-model is complicated as often the case in real products. To aid in the creation of the shell-element mesh there is commercial software available for the extraction of the mid-surfaces in the CAD-model. In this paper two different software for mid-surface extraction are tested, both included in pre-processors for high-end FEA solvers. The software was tested on six different die-cast or injection moulded parts, all components in consumer products available on the market.

The result is that the software can extract the individual mid-surfaces well but the connections between them are often not created properly.

Furthermore the software cannot, as expected, deal with the regions that divert too much from being thin-walled. This paper present an idea on how treat these regions by retrieving suitable representations from a depository of representations known from experience to represent the geometry well and insert them in the appropriate position in the FEA-model automatically.

To show the feasibility of the idea a demonstrator program created in CATIA V5 using VBA is also presented in this paper.

Identifiers
urn:nbn:se:hj:diva-1726 (URN)
Available from: 2007-08-03 Created: 2007-08-03 Last updated: 2010-01-12Bibliographically approved
4. A CAD-integrated system for automated idealization of CAD-models for finite element analysis
Open this publication in new window or tab >>A CAD-integrated system for automated idealization of CAD-models for finite element analysis
2005 (English)In: Proceedings of IDETC/CIE 2005: ASME 2005, 2005Conference paper, Published paper (Refereed)
Abstract [en]

The work described in this paper seeks to minimize the time spent on manually reducing thin-walled CAD-geometry into surface idealizations. The purpose of the geometrical idealizations is the creation of shell element meshes for FE-calculations. This is motivated by time and thereby cost savings and also to make the results of the calculations available earlier in the product development process allowing the results to guide the designs to a larger extent.

Systems for automated geometry idealization and creation of FE-models already exist, but this paper describes a novel approach with the working principle of analyzing how the CAD-specific features of the CAD-file history tree are constituted. This information is used to automatically create the best practice geometrical idealization in the same CAD-model.

Evaluation of the performance of the system in an industrial example is also presented.

Keywords
KBE, CAD, Finite element analysis, Simulation-Driven design, CATIA V5
Identifiers
urn:nbn:se:hj:diva-1725 (URN)
Available from: 2007-08-03 Created: 2007-08-03 Last updated: 2010-01-12Bibliographically approved
5. Managing Product and Process Knowledge in CAD-Systems
Open this publication in new window or tab >>Managing Product and Process Knowledge in CAD-Systems
2009 (English)In: NordPLM'09: Proceedings of the 2nd Nordic Conference on Product Lifecycle Management / [ed] Johan Malmqvist and Göran Gustafsson, Göteborg: Chalmers University of Technology , 2009, p. 51-61Conference paper, Published paper (Refereed)
Abstract [en]

In order to codify, manage, and reuse the knowledge gained from pursing product development projects, CAD-programs have started to provide functionality for supporting this activity. Since the primary purpose of the CAD program is to interactively define geometry, the functionality has been integrated primarily to be used on the parameters of the CAD-model of the design instance. This paper explores how the functionality can be used in a broader scope, managing and automatically reusing knowledge for all designs intended for a certain production process. This is facilitated by automatically converting an arbitrary CAD-model of a design to a format that is accessible for knowledge handling and reuse functionality in the CAD-system. A conversion algorithm for the processes die-casting and powder metallurgy pressing sintering is presented, as well as showing how the knowledge can be represented in the CAD-system. This will allow engineers to actively participate in the knowledge build-up and insure that the general knowledge can be handled in the companies’ IT-infrastructure.

Place, publisher, year, edition, pages
Göteborg: Chalmers University of Technology, 2009
Keywords
Production process, Knowledge-based engineering, CAD, Application programming, Knowledge management
Identifiers
urn:nbn:se:hj:diva-10698 (URN)978-91-975079-7-4 (ISBN)
Available from: 2009-10-21 Created: 2009-10-21 Last updated: 2010-04-12Bibliographically approved
6. Automatic preparation of CAD-generated solid geometry for FE-meshing
Open this publication in new window or tab >>Automatic preparation of CAD-generated solid geometry for FE-meshing
2005 (English)In: NAFEMS World Congress 2005, 2005, p. 101-Conference paper, Published paper (Refereed)
Abstract [en]

In recent years the computing power and meshing algorithms have developed to a state where FEA problems can often be solved directly using the solid geometry. However for complex geometry and complicated calculations there will for the foreseeable future be a need for geometrical idealizations.

To reduce the time spent on making geometrical idealizations in repetitive FEA, a CAD-integrated KBES (Knowledge Based Engineering System) has been developed. The KBES creates a surface idealization from a thin-walled solid by utilizing generic modelling knowledge and by registering information about the CAD-specific features which the designer uses to define the solid geometry. From this information a corresponding surface idealization is created in the same CAD-system. This allows an updated and parametric geometry idealization of the complete CAD-geometry to be created with a degree of automation directly in the CAD-system.

Primarily the mid-surfaces oriented in the tooling draft direction are created by evaluating the sketches which the features of the CAD-model are based on. The KBES also trims the created surfaces, thus facilitating the subsequent meshing.

The KBES has been developed in CATIA V5 (Dassault systemes). It contains rules defined in CATIA knowledgeware which trigger sequential routines written in VBA (Visual Basic for Applications). An industrial application example where the system is used to automatically create a surface idealization for a die-cast part is also presented.

National Category
Engineering and Technology Reliability and Maintenance
Identifiers
urn:nbn:se:hj:diva-1724 (URN)1-874 376 034 (ISBN)
Available from: 2007-08-03 Created: 2007-08-03

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  • modern-language-association-8th-edition
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  • nn-NO
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  • Other locale
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Output format
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