Does Form follow Function? Connecting Function Modelling and Geometry Modelling for Design Space Exploration
Doktorsavhandling, 2020

The aerospace industry, representative of industries developing complex products, faces challenges from changes in user behaviour, legislation, environmental policy. Meeting these challenges will require the development of radically new products.

Radically new technologies and solutions need to be explored, investigated, and integrated into existing aerospace component architectures. The currently available design space exploration (DSE) methods, mainly based around computer-aided design (CAD) modelling, do not provide sufficient support for this exploration. These methods often lack a representation of the product’s architecture in relation to its design rationale (DR)—they do not illustrate how form follows function. Hence, relations between different functions and solutions, as well as how novel ideas relate to the legacy design, are not captured. In particular, the connection between a product’s function and the embodiment of its solution is not captured in the applied product modelling approaches, and can therefore not be used in the product development process.

To alleviate this situation, this thesis presents a combined function and geometry-modelling approach with automated generation of CAD models for variant concepts. The approach builds on enhanced function means (EF-M) modelling for representation of the design space and the legacy design’s position in it. EF-M is also used to capture novel design solutions and reference them to the legacy design’s architecture.

A design automation (DA) approach based on modularisation of the CAD model, which in turn is based on the functional decomposition of the product concepts, is used to capture geometric product information. A combined function-geometry object model captures the relations between functions, solutions, and geometry. This allows for CAD models of concepts based on alternative solutions to be generated.

The function- and geometry-exploration (FGE) approach has been developed and tested in collaboration with an aerospace manufacturing company. A proof-of-concept tool implementing the approach has been realised. The approach has been validated for decomposition, innovation, and embodiment of new concepts in multiple studies involving three different aerospace suppliers. Application of FGE provides knowledge capture and representation, connecting the teleological and geometric aspects of the product. Furthermore, it supports the exploration of increasingly novel solutions, enabling the coverage of a wider area of the design space.

The connection between the modelling domains addresses a research gap for the “integration of function architectures with CAD models”.

While the FGE approach has been tested in laboratory environments as well as in applied product development projects, further development is needed to refine CAD integration and user experience and integrate additional modelling domains.

knowledge based engineering

design automation

engineering design

systems engineering

design space exploration

product models

product development

function modelling

Opponent: Helen Louise Lockett, Open University, UK


Jakob Müller

Chalmers, Industri- och materialvetenskap, Produktutveckling

Lessons learned from the application of enhanced Function-Means modelling

Proceedings of Design 2020,; (2020)p. 1325-1334

Paper i proceeding

Enhanced function-means modeling supporting design space exploration

Artificial Intelligence for Engineering Design, Analysis and Manufacturing: AIEDAM,; (2019)

Artikel i vetenskaplig tidskrift

Connecting functional and geometrical representations to support the evaluation of design alternatives for aerospace components

Proceedings of the International Conference on Engineering Design, ICED,; Vol. 2019-August(2019)p. 1423-1432

Paper i proceeding

Müller, J.R., Borgue, O., Panarotto, P., Isaksson, O. Mapping the design space in function and geometry models for re-design for additive manufacturing

Müller, J.R., Panarotto, M. and Isaksson, O. Function model based generation of CAD model variants

M¨uller, J.R., Panarotto, M., Isaksson, O., Design Space Exploration of a Jet Engine Component using a Combined Object Model for Function and Geometry

The aerospace industry has to radically change its products: challenges such as new limits for emissions such as CO2, NOx or noise, as well as the ongoing COVID pandemic require products that highly outperform todays aircraft, engines and components. Aerospace engineers need to find new functions and solutions to be able to develop the aircraft of the future.

However, the methods which product developers use to develop new products – the commonly used 3D geometry models in the form of computer aided design (CAD) – do not support the introduction of radically new solutions New functions and solutions need to be introduced – but CAD models are not structured in functions and solutions but features and parameters. While models explicitly representing such functions and solutions exist, are they not widely used. Furthermore, do they not support engineering analysis such as aerodynamic, thermodynamic or structural behaviour, which is needed for the evaluation of a new concept. No product development method or model could be identified which can represent both: a product’s form and function, and how they are connected.

To solve this problem, a method for combined function and geometry exploration (FGE)has been developed and tested. The FGE method enables product developers to explore novel solutions in a function model, which is directly coupled to a CAD model. The method relies on an underlying object model, which maps the product’s geometric features to their respective functions. As such, it combines the information of what a product is supposed to do with the model of its shape: how the form follows the function.

In a first step, the existing product has to be composed from the available CAD model into the function model, and the respective links have to be established. In a next step, developers introduce new functions and solutions into the function model. These are then instantiated into alternative concepts, from which the tool automatically generates CAD models. The method has been implemented in a proof-of-concept tool. The FGE method, through this tool, has been applied in three different studies, in collaboration with industrial partners from the aerospace industry. FGE has proven to represent the design space for a product, enable the introduction of novel solutions and functions, represent the design rationale of a product and automatically generate the respective CAD models. From this it can be stated that it supports the development and exploration of more, and more novel, alternative product concepts. Practitioners have called it "one possibility to generate, and evaluate, lots of concepts”.

VIrtuell TUrbinModuldemonstrator (VITUM)

VINNOVA, 2014-11-03 -- 2017-06-30.

RIQAM - Radical Innovation and Qualification using Additive Manufacturing

Rymdstyrelsen, 2017-08-01 -- 2018-12-31.

Digitala Experiment - metoder att utvärdera alternativa teknologier i tidiga produktkoncept

VINNOVA, 2017-11-10 -- 2020-12-31.


Annan maskinteknik

Rymd- och flygteknik





Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 4879


Chalmers tekniska högskola



Opponent: Helen Louise Lockett, Open University, UK

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