On the Design of Functionally Integrated Aero-engine Structures: Modeling and Evaluation Methods for Architecture and Complexity
Doctoral thesis, 2019

The drive for airplanes with radically reduced fuel consumption and emissions motivates engine manufacturers to explore innovative engine designs. The novelty of such engines results in changed operating conditions, such as newly introduced constraints, increased loads or rearranged interfaces. To be competitive, component developers and manufacturers must understand and predict the consequences of such changes on their sub-systems. Presently, such assessments are based on detailed geometrical models (CAD or finite element) and consume significant amounts of time. The preparation of such models is resource intensive unless parametrization is employed. Even with parametrization, alternative geometrical layouts for designs are difficult to achieve. In contrast to geometrical model-based estimations, a component architecture representation and evaluation scheme can quickly identify the functional implications for a system-level change and likely consequences on the component. The schemes can, in turn, point to the type and location of needed evaluations with detailed geometry. This will benefit the development of new engine designs and facilitate improvements upon existing designs. The availability of architecture representation schemes for functionally integrated (all functions being satisfied by one monolithic structure) aero-engine structural components is limited.

The research in this thesis focuses on supporting the design of aero-engine structural components by representing their architecture as well as by developing means for the quantitative evaluation and comparison of different component designs. The research has been conducted in collaboration with GKN Aerospace Sweden AB, and the components are aero-engine structures developed and manufactured at GKN. Architectural information is generated and described based on concepts from set theory, graph theory and enhanced function–means trees. In addition, the complexities of the components are evaluated using a new complexity metric. Specifically, the developed modeling and evaluation methods facilitate the following activities:

·         identification and representation of function–means information for the component

·         representation and evaluation of component architecture

·         product complexity evaluation

·         early selection of load path architecture

·         impact assessment for the component’s functioning in the system

By means of the methods developed in this thesis, the design rationale for a component is made explicit, and the storing, communicating and retrieving of information about the component in the future is enabled. Through their application to real-life engine structures, the usability of the methods in identifying early load carrying configurations and selecting a manufacturing segmenting option is demonstrated. Together, the methods provide development engineers the ability to compare alternative architectures. Further research could focus on exploring the system (engine) effects of changes in component architecture and improvements to the complexity metric by incorporating manufacturing information.

Product Architecture

Aero-engine Structures

Configurable Components

Load Paths

Design Product Complexity

Functionally Integrated Product Architecture

Product Development

Structural Complexity

Function–Means Modeling

Room EC, Hörsalsvägen 11, Göteborg
Opponent: Associate Professor Marija Jankovic, Industrial Engineering, CentraleSupélec, Paris


Visakha Raja

Chalmers, Industrial and Materials Science, Product Development

Modelling-integrated product architectures: an aero engine component example

Smart Innovation, Systems and Technologies,; Vol. 134(2019)p. 847-858

Paper in proceeding

Describing and evaluating functionally integrated and manufacturing restricted product architectures

Research in Engineering Design - Theory, Applications, and Concurrent Engineering,; Vol. 29(2018)p. 367-391

Journal article

An optimization-based approach for supporting early product architecture decisions

21st International Conference on Engineering Design, ICED 2017, Vancouver, Canada, 21-25 August 2017,; Vol. 4(2017)p. 377-384

Paper in proceeding

Exploring Influence of Static Engine Component Design Variables on System Level Performance

22nd International Symposium on Air Breathing Engines, ISABE2015,; (2015)

Other conference contribution

Generic Functional Decomposition of an Integrated Jet Engine Mechanical Sub System Using a Configurable Component Approach

22nd ISPE Inc. International Conference on Concurrent Engineering, CE 2015, TU Delft, Netherlands, 20-23 July 2015,; Vol. 2(2015)p. 337-346

Paper in proceeding

Raja, V., Isaksson, O. and Kokkolaras, M. (2019) ‘A Simulation-assisted Complexity Metric for Design Optimization of Integrated Architecture Aero-engine Structures’, Structural and Multidisciplinary Optimization (Accepted for publication 03 May 2019)

An aero engine is a complex piece of equipment and the components inside it, such as the compressors, turbines and associated structural frames share this complexity. Designing components is difficult, not just due to the complexity but also due to the incremental nature of aero-engine development. It is not easy to pick out which component regions are interconnected in what ways, and to say exactly which regions satisfy what functions for the engine. This calls for development of methods to visually describe and quantitatively evaluate how an engine component satisfies its functional requirements. Moreover, addressing sustainability challenges demands radical improvements in present engine designs or proposal of new designs. As the engines in operation today are highly optimized, novel means must be identified to improve present designs or propose new designs. Good design builds on good methods and this research was focused on improving and adapting design methods for aero engine components such as its structural frames.

A component level improvement in design that results in, say reducing aircraft fuel consumption even by 0.05%, can save several thousand USD for an airline company per year, and can reduce the environmental impact of aviation. Methods developed in this thesis identifies critical functions that an engine component satisfies and discover previously unseen inter-relationships among its functions. The methods also enable storing information about established designs and using it as a starting point for future designs. An un-complicated connection with manufacturing is also facilitated by providing a way for assessing the influence of different manufacturing options on component operation. Furthermore, by the development of a metric of complexity for engine components such as its structural frames, the research supports the comparison, optimization, and selection of various engine component designs. Together, the methods developed in this thesis will enhance a development engineer’s ability to evaluate alternative component designs and select the most suitable one.

This thesis will be of interest to both practicing engineers and researchers concerned with engineering design in general and aero-engine component design in particular.

Subject Categories

Production Engineering, Human Work Science and Ergonomics

Other Mechanical Engineering

Aerospace Engineering



Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 4584


Chalmers University of Technology

Room EC, Hörsalsvägen 11, Göteborg

Opponent: Associate Professor Marija Jankovic, Industrial Engineering, CentraleSupélec, Paris

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