Functional Modelling in a Design Support System
Contribution to a Designer's Workbench

Year: 1999
Author: Jensen, Thomas
Supervisor: Andreasen, Mogens Myrup; Hansen, Claus Thorp
Institution: Technical University of Denmark (DTU)
Page(s): 309
ISBN: 87-90130-20-0

Abstract

The phenomenon treated in this thesis is functional modelling during the conceptual phase of the mechanical design process. The research contributes to the development of a computer-based design tool, a Designer's Workbench (DWB), for supporting functional modelling. Through practical experiences and literature studies, it is argued that an industrialisation of the design process may be driven by an incentive instrumentation based upon a shaping of design theory and methodology in combination with the utilisation of information technology. Issues relevant to the development of a DWB for supporting functional modelling are identified.
A research task is formulated based upon following research questions:
• How can design intent be linked to a structural product model?
• How can behavioural design knowledge be represented in organ units?
• How can a design working-pattern be based upon the utilisation of organ units for an on-line capturing of design intent and behavioural design knowledge?
A discussion on how to scientifically approach the research task is taken, and it is argued for a balanced theoretical and empirical method for the development of a DWB.
Theories of technical systems and design processes are outlined with focus upon the WDK School and German design research. An overview of state of the art in research on computer-based design tools is given. A taxonomy for categorisation of design tools is proposed, and existing systems are mapped to identify space for novel scientific contributions.
The concept of functionally complete organs and their structure of wirk elements are treated. An organ based behaviour/structure mapping is proposed as a means for linking design intent to a structural product model. A wirk element is described as a functionally active derivative of a form element, and the relations between wirk elements in the organ domain and form elements in the part domain are identified. State transitions and life phase modelling are treated in relation to the representation of wirk elements, including the phenomena of function integration and space ownership modelling. A uniform concept for modelling of behaviour is proposed and related to a quantitative representation of behavioural design knowledge. Contributing to a theory of properties a classification of organ unit attributes is developed. An information model for a generic organ unit is proposed and the structuring of organ units in a conceptual design catalogue is treated.
A combined design for reuse and design by reuse process is proposed, where organ units represents a modelling language enabling a formal on-line design preparation. Paper and computer-based prototypes are developed. Empirical studies are conducted to analyse the fitness of a DWB to the modelling activity in conceptual design. The studies indicate, but do not scientifically prove that designing on a DWB may not fit well to the design process.
Resumé
Denne afhandling omhandler fćnomenet funktionsmodellering i den konceptuelle fase af mekanisk konstruktion. Forskningen bidrager til udviklingen af et computerbaseret konstruktionsvćrktøj, en Designer's Workbench (DWB), til understøtning af funktionsmodellering.
Gennem praktiske erfaringer og litteraturstudier argumenteres det, at en industrialisering af konstruktionsprocessen kan anspores af en instrumentering baseret på en tilpasning afkonstruktionsteori og metodologi i kombination med udnyttelsen af informationsteknologi. En rćkke relevante aspekter identificeres for udviklingen af en DWB til funktionsmodellering.
En forskningsopgave formuleres ud fra følgende forskningsspørgsmål:
• Hvordan kan konstruktionsintention knyttes til en strukturel produktmodel?
• Hvordan kan funktionsviden reprćsenteres i organ units?
• Hvordan kan et arbejdsmønster for konstruktion baseres på udnyttelsen af organ units med en on-line indfangning afkonstruktionsintention og funktionsviden? Videnskabelige fremgangsmåder for forskningsopgaven diskuteres og der argumenteres for en balanceret teoretisk og empirisk metode for udviklingen af en DWB. Teorier for tekniske systemer og konstruktionsprocesser beskrives med fokus på WDK skolen og tysk konstruktionsforskning. Der gives en state-of-the-art oversigt indenfor forskning i computerbaseret konstruktionsvćrktøjer. En taksonomi foreslås til kategorisering af vćrktøjer, og eksisterende vćrktøjer kortlćgges for at sikre videnskabelig nyhedsvćrdi. Funktionelt komplette organer og deres struktur af wirk elementer behandles. En organbaseret sammenhćng mellem funktion og struktur foreslås som middel til at knytte konstruktionsintention til en strukturel produktmodel. Et wirkelement beskrives som en afledt af et funktionelt aktivt formelement, og relationerne mellem wirkelementer i organdomćnet og formelementer i partdomćnet identificeres. Tilstandsćndringer og livfasemodellering behandles i relation til reprćsentation afwirkelementer, og fćnomenerne funktionsintegration og space ownership modellering knyttes hertil. Et uniformt koncept for funktionsmodellering foreslås og relateres til en kvantitativ reprćsentation af funktionsviden. Som et bidrag til en egenskabsteori udvikles en klassifikation af attributter for en organ unit. Der foreslås en informationsmodel for en generisk organ unit og struktureringen af organ units i et konstruktionskatalog behandles. En genbrugsorienteret konstruktionsproces foreslås, hvor organ units reprćsenterer et konstruktionssprog, der muliggør en formel on-line konstruktionsforberedelse. Papir og computerbaseret prototyper er udviklet. Der er gennemført empiriske studier til analyse af egnetheden for konceptuelle modelleringsaktiviteter med en DWB. Studierne indikerer, men beviser ikke videnskabeligt, at en DWB nćppe er egnet til støtte af konstruktionsprocessen.