LICENTIATE T H E S I S
Luleå University of Technology
Department of Applied Physics and Mechanical Engineering Division of Computer Aided Design
Life Cycle Simulation Support for Functional Products
Patrik Boart
Life cycle simulation support for functional products
Patrik Boart
Division of Computer Aided Design
Luleå University of Technology
ISSN: 1402-1757
ISRN: LTU-EX—05/20--SE
© 2005 Patrik Boart
Department of Applied Physics and Mechanical Engineering Division of Computer Aided Design
Luleå University of Technology SE-971 87 Luleå
SWEDEN
Printed by Universitetstryckeriet 2005
This research has been carried out in corporation between Luleå University of Technology and the Volvo Aero Corporation. The research and case studies were performed at the Design Methods & Systems department at Volvo Aero. I am very grateful for the funding by Volvo Aero and NFFP (VINNOVA’s Nationellt Flygtekniskt Forskningsprogram), thereby allowing me to concentrate on this specific research area that is close to my passion for engineering and computers.
I would like to express my gratitude to my supervisor, Bengt-Olof Elfström, for his enthusiasm and belief in my ideas and excellent guidance in my research efforts.
I would also like to thank Ola Isaksson for always finding the spare some time to give me guidance, even during weekends when needed. I would like to thank all my colleagues at the Division of Computer Aided Design, my co-authors and my colleagues at the department Design Methods & Systems at Volvo Aero.
Last I would like to thank my family and friends who have always stood by me giving me their support and comfort.
Luleå May 2005
Patrik Boart
This thesis includes an introduction and the following papers:
Paper A
Boart P., Sandberg M., Nergård H., Isaksson O.
A knowledge enabled engineering approach for conceptual design of life cycle properties.
Submitted for publication in the Journal of Computing and Information Science in Engineering, JCISE.
Paper B
Sandberg, M., Boart, P., Larsson, T.
Product life-cycle simulation application for cost estimation and conflict prevention in conceptual design of jet-engine components.
Submitted for publication in the journal Concurrent Engineering: Research and
Applications, CERA.
Abstract
Business to business cooperation is undergoing large changes, resulting in new requirements on how to develop products, and thereby forcing companies to optimize their part of the total product system. Aerospace business agreements are being made on a life cycle basis where the actual product ownership often remains with the manufacturer. Revenue for aero engine manufacturers and their engine programs appear late in the engine life cycle, not during market introduction when large discounts are common. An engine developed for the sale of spare parts is not optimized for the owner. The key when owning and producing engines is to develop engines with a minimum life cycle cost.
As the development of functional (Total Care) products includes the development of both hardware and accompanying services, people from all areas and their knowledge will be needed in the decision-making. This will be especially important in conceptual engineering design phases where knowledge of the design requirements and constraints is usually imprecise and incomplete and where few support tools to support this phase exist.
Knowledge Enabled Engineering includes Knowledge Based Engineering and other knowledge rich strategies, and aims to support or perform engineering activities with the help of available techniques and methods. The Knowledge Enabled Engineering approach presented here embeds methods used later (downstream) to simulate the effects making information readily available early on.
Numerous decision support systems exist where knowledge from a few disciplines has been modelled. However, this is not enough with a life cycle focus.
The basis in early decision-making requires knowledge from all phases of the product’s life cycle. The presented work shows how a decision support system can be used to capture and present knowledge extracted from performance, manufacturing and maintenance activities, creating a better foundation for making decisions regarding life cycle issues.
The described method shows a way to simulate business scenarios and its product solutions based on a technical basis normally found later (downstream) in the product development process. Also shown is how a decisions support system can be used to capture downstream knowledge from design, manufacturing and maintenance activities, thus allowing the effects of the life cycle to be already simulated in the conceptual phase. Engineers can then change the design and directly assess the life cycle cost also in the conceptual phase allowing fast iterations, and thereby design the life cycle of a product based on knowledge from design, manufacturing and maintenance disciplines. Optimization in a global perspective will allow the right decision to be made in the early phases with a clear understanding of how life cycle issues are affected depending on the choices made.
Keywords: Knowledge enabled engineering, conceptual design, life cycle design,
downstream knowledge
Content
1 INTRODUCTION... 1
1.1 BACKGROUND... 1
1.2 MOTIVATION... 1
1.3 DELIMITATION OF THE RESEARCH... 2
2 RESEARCH CONTEXT... 2
3 KNOWLEDGE DOMAINS ... 2
3.1 PRODUCTDEVELOPMENT... 2
3.2 CONCURRENTENGINEERING... 3
3.2.1 Metrics and Measures ... 4
3.2.2 Capturing life cycle intent... 4
3.2.3 Decision support system... 5
4 INDUSTRIAL FRAME OF REFERENCES... 5
5 RESEARCH QUESTION ... 7
6 RESEARCH DESIGN ... 7
6.1 RESEARCHPURPOSE... 7
6.2 RESEARCHAPPROACH... 7
7 RESEARCH PROJECT AND RESEARCH PROCESS... 8
7.1 BACKGROUND TO THE RESEARCH PROJECT... 8
7.2 THERESEARCHPROCESS... 8
8 KNOWLEDGE ENABLED ENGINEERING APPROACH ... 9
8.1 CAPTURE OF ENGINEERING KNOWLEDGE... 10
8.2 AUTOMATION OF ENGINEERINGACTIVITIES... 10
8.3 QUALITY CONTROL OF ENGINEERING ACTIVITIES... 10
9 CASE DESCRIPTION, ANALYSIS AND RESULTS ... 10
9.1 FLANGE DESIGN PROCESS... 10
9.2 FLANGE DESIGN APPLICATION... 11
9.3 A COMMON LIFE CYCLE VIEW... 14
9.4 ANALYSIS... 14
10 SUMMARY OF PAPERS ... 15
10.1 PAPER A ... 15
10.1.1 Summary...15
10.2 PAPER B ... 15
10.3 SUMMARY... 15
11 CONCLUSIONS ... 16
12 DISCUSSIONS ... 16
13 FUTURE WORK ... 17
REFERENCES... 18
1 Introduction
1.1 Background
Business to business cooperation is undergoing large changes that closely fit the transformational driving forces, e.g. those identified by Swedish Technology Foresight on future product systems 2015 [1].
• Individuals and companies act on local and global markets.
• Circular business systems: closed resource flows and scale of functions.
• Intellectual capital is the most important means of competition.
• Complexity in upcoming systems is leading to new demands.
Due to the trends presented above, business is changing and creating new requirements on how to develop products in business-to-business relations, forcing companies to optimize their part of the total product system. Aerospace business agreements are being made on a life cycle basis where the actual product ownership often remains with the manufacturer. Revenue for aero engine manufacturers and their engine programs typically appear late in the engine life cycle, though not from the price of the product itself where large discounts are common. An engine developed for the sale of spare parts is not optimized for the owner. The key when owning and producing engines is to develop engines with a minimum life cycle cost.
Developing a functional (Total Care) product [2] in a Business-to-Business relation creates an enormous need to share information between the involved companies. As the development of the functional products includes the development of both hardware and accompanying services, people from all areas and their knowledge will be needed in the decision-making. This is important in the conceptual engineering design phases when knowledge of the design requirements and constraints is usually imprecise and incomplete and where few support tools exist [3].
The further the product development process proceeds, the more knowledge is gained from the performed activities. Because design is an open-ended problem, each new piece of added information affects what decision seems to lead to the best solution [4]. Decisions more or less constrain the amount of possible solutions, with those being taken early on having a major impact as they limit the solution space.
1.2 Motivation
A product development process consists of numerous activities to be performed.
Developing a product in Business-to-Business relations requires information to be
shared between companies. The information shared comes from activities done
within each company in their respective processes. An activity to be performed
needs information from other activities within or outside the company. The output
from one activity may then be the input for another. The lead-time for the total
product development process is then dependent on the lead-time for each activity
and for sharing the information needed to perform the activities.
Little is known about the final product at the beginning of the product development process. Each performed activity gathers more knowledge about what the final properties of the product will be. As functional products ask for the ability to define the properties of the final product already in the conceptual phase, knowledge from activities normally done later in the process (downstream activities) is now needed early on. To extract knowledge from a downstream activity, one will need to perform the process of that activity. The more activities that can be performed early will then contribute to an understanding of the decisions before they are made.
1.3 Delimitation of the Research
When developing a commercial jet engine, requirements and interface information are exchanged between several companies working together as well as between disciplines inside each company. To limit the overall problem the focus has been to explore how earlier phases within a single company can be supported in the conceptual development phase of functional products. The view of the conceptual phase where companies work together has been left to the continuation of the research.
2 Research Context
As a PhD student from Luleå University of Technology stationed at Volvo Aero in Trollhättan, Sweden, the work has been carried out to develop a support system for the conceptual design of structural components in commercial aircraft engines, where valuable access has been afforded to the aerospace industry and their product development processes. Volvo Aero develops and manufactures high-technology components for aircraft-, rocket- and gas turbine engines. Volvo Aero also offers extensive aviation services - including leasing, logistics, asset management, inventory sales, distribution and redistribution, as well as overhaul and repair of aircraft engines. Regular visits were made to the Division of Computer Aided Design at Luleå University of Technology to participate in courses, cooperate with other PhD students (papers A and B) and for academic supervision.
3 Knowledge Domains
A roadmap is presented starting with the area of product development, followed by concurrent engineering where three areas are used to position this work’s contribution.
3.1 Product Development
Ulrich & Eppinger [5] define product development as:
“...the set of activities beginning with the perception of a market opportunity and ending in the production, sale and delivery of a product.”
This product development view explicitly focuses on engineered, discrete and
physical products. Functional products expand the focus in product development to
cover the development of both hardware and services [2]. Aerospace business agreements are being made on a life cycle basis where the actual product ownership often remains with the manufacturer. Revenue for aero engine manufacturers and their engine programs appear late in the engine life cycle, though not during market introduction when large discounts are common (paper A). The search for literature with a life cycle perspective within product development will lead to Concurrent Engineering.
3.2 Concurrent Engineering
Kusiak [6] refers to concurrent engineering (CE) as:
“...the practice of incorporating various values of a product into the design at its early stages of development. These values address the entire life cycle of the product and include not only its primary functionality but also producibility, assemblability, testability, serviceability, and even recyclability.”
Prasad [4][7] addresses a number of fields to illustrate how a full CE system will work, Figure 1.
Models, Methods, Metrics
and Measures Virtual
Team
Cooperative Work groups Product
Realization Taxonomy
Technology Team Logical
Team
System Engineering
CE Techniques
Process Reengineering Information
Modeling The Whole System
Life-cycle Management
Personnel Team Manufacturing Competitiveness
Models, Methods, Metrics
and Measures Life-cycle Mechanization Intelligent
Information System
Frameworks and Architectures
Product Development Methodology
Total Value Management Concurrent
Function Deployment
IDP Deployment Methodology
Integrated Product and Process Organization (PPO) Wheel
Integrated Product Development (IPD) Wheel
Capturing Life-cycle Intent
Decision Support System
CE Metrics and Measures
Figure 1. Illustration over a full CE system, based on [7][4].
This research’s contribution focuses mainly within the areas CE Metrics and
Measures, Decision Support System and Capturing Life-Cycle Intent, all located in
the IPD wheel, Figure 1.
3.2.1 Metrics and Measures
More knowledge is gathered each year within each discipline, thus increasing the understanding of how design decisions will affect the end result of the product.
These design practices are formalized today as design for X, such as design for manufacturing, assemblability, maintainability, etc. [8]. To find an optimal product, all DFX issues need to be considered simultaneously, thereby inevitably creating design conflicts. Still, design is decisions where some sort of trade off is done, e.g. design issues against manufacturing issues, performance against cost, etc.
[4].
3.2.2 Capturing life cycle intent
A wish to allow modification and iteration until all product life-cycle specifications are fully satisfied has been addressed in the area of capturing life cycle intent, Figure 1. Numerous efforts have been done to support different disciplines where many knowledge-modelling techniques have been developed,Table 1. The main idea has been to show how these methods can reduce the lead-time of the product development process and increase the quality of the processes. So far, little focus has been on using these methods for improving the basis for conceptual decisions, with efforts to date mostly coming from within the disciplines, design, manufacturing and analysis. To receive knowledge about how the life cycle of a product will be affected by early decisions, more disciplines needs to involve their knowledge.
Knowledge Modelling Technique
Product Discipline Discipline relationship Author
Expert system (ES)
Generic Design, Manufacturing
Feature extraction and cost estimation of manufacturing
Venkatachalam [9], 1993
Kitchen design
Design Capturing of design rationale for design of kitchen
Mørch [10], 1994 Design
rationale
(DR) Chemical
Plant
Design Capturing of design rationale behind a chemical plants
Chung and Goodwin [11], 1998
Wing Structure
Performance and manufacturing
Performance and manufacturing analysis of a wing
Zweber et al. [12], 1998
Wing Structure
Design, Cost analysis
Design, Cost estimation (manufacturing concerns)
Blair and Hartong [13], 2000 Car body
structure
Design, Analysis Pre-processing of design Chapman and Pinfold [14], 2001
Aerospace Design, Analysis, Manufacturing
Manufacturing and performance evaluation of design
Schueler and Hale [15], 2002 Knowledge
based engineering (KBE)
Buildings Design, Analysis Cost estimation, scheduling on buildings
Mohamed and Celik [16], 2002
- Manufacturing,
Analysis
Moulding evaluation Lou et al. [17], 2004 Insurance Analysis Risk analysis of drivers Daengdej et al.
[18],1999 Low Power
Transformers
Design, Analysis Product and process design Kwong and Tam [19], 2002
- Design, Analysis Material selection Amen and Vomacka
[20], 2001
Travel Agency Analysis Travel planner Chaudhury et al. [21], 2004
Agents and case based reasoning (CBR)
Induction motors
Product Support Diagnostics Yang et al. [22], 2004
Table 1. Knowledge Modelling Techniques.
3.2.3 Decision support system
A field called decision support system is found with the IPD wheel, Figure 1.
Support is needed to help participating teams cooperate and achieve a balanced view before design decisions. With the help of modelling techniques presented in Table 1, different support system are developed to assist engineers perform their tasks. A number of Knowledge Based System (KBS) definitions exist; see Table 2.
Support system for pre-processing of a car body design [14], performance and manufacturing analysis of a wing [12] was developed with a KBE modelling technique.
Definitions on Knowledge Based Systems Author
“Knowledge Based Systems are a special class of computer programs that purport to perform, or assist humans in performing, specified intellectual tasks.”
Dixon [23]
“KBE systems aim to capture product and process information in such a way as to allow businesses to model engineering design processes, and then use the model to automate all or part of the process.”
Chapman [14]
“A Knowledge-Based System is the one that captures the expertise of individuals within a particular field, and incorporates it and makes it available within a computerized application.
A KBE application is further specialized and typically has the following components:
Geometry Configuration and Engineering Knowledge.”
Lovett [24]
“KBE is a technology that allows an engineer to create a product model based on rules that capture the methodology used to design, configure and assemble products.
KBE facilitates the capture of the intent behind the product design by representing the why and how in addition to the what of a design.”
Bailey [25]
“Knowledge Based Engineering is the execution of engineering tasks using knowledge that is not normally immediately accessible to the designer or engineer, and that has been purposefully accumulated and stored for use by the designer or engineer, usually (but not always) in some computer-mediated form. Thus, KBE usually (but not always) implies the use of some kind of computer system, examples of which include the so-called expert systems, web-based knowledge bases, and the like.”
Penoyer &
Burnett [26]
Knowledge Based Engineering:
“The use of advanced software techniques to capture and re-use product and process knowledge in an integrated way.”
Stokes [27]
Table 2. Definitions on Knowledge Based Systems.
4 Industrial Frame of References
This study has been conducted within the framework of the National Aeronautics Research Program (NFFP). Founded by the Swedish government with the aim to create the necessary conditions for Swedish participation in international research programs within the aerospace area, the NFFP’s purpose is to strengthen the competitiveness of Swedish aerospace by reinforcing and coordinating the national research resources in industry, institutions and universities. By creating a strong competence centre, NFFP also stimulates the creation of the necessary conditions for international research cooperation within industry and research foundations.
International research cooperation expects previously unavailable and new research result and technologies to become available.
Volvo Aero, whose business idea is to be an independent risk and revenue sharing
partner in cooperation with major engine manufacturers, develops and
manufactures components for commercial and military aircraft engines and gas turbines. Their partnerships include GE in the GEnx engine for Boeing’s new 787 Dreamliner aircraft, where they are responsible for the design, development, manufacturing and product support of the Fan Hub Frame, Turbine Rear Frame and Booster Spool, and with Rolls Royce in the Trent 900 engine for the super jumbo Airbus A380, where they are responsible for the design, development and manufacturing of the Intermediate Compressor Case, a complex structural component between the IP and HP compressors. Here, their responsibility covers everything from development, design, manufacturing and product support for the supply of spare parts throughout the entire lifetime of the engine. The company’s specialization strategy has proven highly successful: more than 80 percent of all new commercial aircraft with 100 or more seats are equipped with engine components from Volvo Aero. Volvo Aero is one of the few companies in the European space program that provide rocket engine turbines and combustion chambers/ nozzles. Over the last 25 years, Volvo Aero has produced more than 1,000 combustion chambers and nozzles for the Ariane 4’s and 5’s.
Luleå University of Technology is involved in many research areas, such as integrated product development, concurrent engineering and functional products.
The Polhem Laboratory is a competence centre initiated by VINNOVA. Member organizations of the Polhem Laboratory include eleven companies, several departments at Luleå University of Technology and two research institutes. The main research goal is to develop technologies for product development and manufacturing through the integration of design, manufacturing, materials engineering and maintenance for application in Swedish industry. The parallel mode of operation is instrumental in developing better products with shorter lead times at lower costs, and in adapting products for manufacturing and maintenance.
To strengthen Sweden’s competitiveness, The Foundation for Strategic Research in Sweden aims to support research in natural science, engineering and medicine.
ProViking [28] is a program within the foundation whose purpose is to strengthen the competitiveness in the Swedish manufacturing industry. ProViking should create improved production systems and new methods for product development through projects conducted between industry and academia. The research result should be transferable and used in the Swedish industry to give a cost efficient production and new or improved products that are competitive on the international market.
The integrated project VIVACE [29] Frame Work 6 program is an Aeronautical Collaborative Design Environment with associated Processes, Models and Methods.
This environment will help to design an aircraft and its engines as a whole, and provide to the aeronautics supply chain in an extended enterprise virtual products with all requested functionality and components in each phase of the product- engineering life cycle. The project consists of 52 partners, 35 companies, 6 research institutes and 11 universities
As a Ph.D. student from Luleå University of Technology stationed at Volvo Aero
Corporation in Trollhättan, and financed by NFFP with involvement into Polhem
laboratory, VIVACE and ProViking allows the author to stand with both feet in the
academic and industrial worlds.
5 Research Question
Aerospace business agreements are being made on a life cycle basis where the actual product ownership often remains with the manufacturer. Designing the actual life cycle of the product is now of great interest. To design the life cycle of a product, understanding how the decisions made during the design process will form the life cycle properties is vital. Could the life cycle of a functional product perhaps be simulated in the conceptual phase and thereby help the engineers to design it?
A research question was then formulated
How can the functional products life cycle be simulated in the conceptual phase?
6 Research Design
6.1 Research Purpose
The actual product ownership remains with the manufacturer developing the functional products. Controlling the life cycle cost of the product is a critical issue.
The life cycle of a product is greatly decided upon in the conceptual phase where few support tools exist [3]. It is difficult or even impossible to compensate for a poor conceptual design when the detailed design phase starts, [30]. As functional products include the development of both hardware and accompanying services, people from all areas and their knowledge will be needed in the decision-making.
There is somehow a need for support systems that can perform activities fast and access the knowledge earlier.
6.2 Research Approach
“ … participatory action research is not just research which we hope will be followed by action! It is action which is researched, changed and re-researched, within the research process by participants. Nor is it simply an exotic variant of consultation. Instead, it aims to be active co-research, by and for those to be helped.
Nor can it be used by one group of people to get another group of people to do what is thought best for them - whether that is to implement a central policy or an organisational or service change. Instead it tries to be a genuinely democratic or non-coercive process whereby those to be helped, determine the purposes and outcomes of their own inquiry. Paradoxically it is quite close to a common-sense way of ‘learning by doing’. But at the same time it is very hard to achieve the ideal conditions for putting it fully into practice”. (Wadsworth [31])
As a researcher stationed at an aerospace manufacturing company working with
the development of decision support system, participatory action research has
become a natural way to perform this research. The conditions for participatory
action research are ideal since the purpose for the research is initially stated at the
company and the company is attempting to go from hardware development to
functional product development.
In participatory action research, the case created inside a company’s own process consists of suitable actions to conduct research on. By arranging the case in the actual product development process, those to be helped in the process determine the purposes and outcomes of their own inquiry. Data collection for the case was done in the form of reading documentation, searching archival records, interviews and participant observations as a researcher involved in the industrial processes.
Working to support an activity in one of the company processes, a number of factors affecting the reliability and validity of the data collected exist. Information regarding activities in the development process is stored in company archives in the form of design instructions, earlier project documentation, etc. Still, to use these instructions, the knowledge normally needed usually only exists from the people within the organization. Building a support system of an activity requires the information (design instructions) and knowledge (people in the organization) of how the activity should be performed to allow the creation of the support system.
7 Research Project and Research Process
7.1 Background to the Research Project
Aerospace business agreements and product offers are becoming more of a functional character. The change from selling hardware to selling a function will affect traditional hardware design. This study is based on the Volvo Aero Corporation strategy to define and evaluate concepts for functional jet engine components where the hardware is only a part of the market offer.
This study has been conducted within the framework of the National Aeronautics Research Program (NFFP) project number NFFP 490 in close collaboration between Volvo Aero Corporation and the division of Computer Aided Design at Luleå University of Technology.
7.2 The Research Process
A research project to define and evaluate concepts for jet engine components was formulated by Volvo Aero Corporation as being a part of the market offer “Total Care” (Functional products). The purpose and research question of the research project were defined during meetings with a group of representatives from Volvo Aero Corporation, University of Manchester Institute of Science and Technology (UMIST) and Luleå University of Technology (LTU).
The meetings with group members were initially close, discussing the concept of functional products. To create a base to work from, a literature study to find related research was started. By trying to answer the initial question and synthesize the literature studied and ideas from meetings new questions were formulated that in turn guided the research process.
Industrial interest in the conceptual phase of the development of functional jet
engine components has initial lead the study towards methods and tools used
during the conceptual phases.
Being located at the department of Design Methods and System with a broad band of expertise and direct access to archives and experts within the company for exploring and synthesising ideas is invaluable.
The author’s role at the department has been to develop support system for conceptual engineering activities. By working 3.5 years with Knowledge Based Systems, such as AML and Knowledge Fusion, to explore the possibilities and disadvantages as a user, developer and teacher has also contributed to the foundation of research.
The perspective of the functional product in aerospace has placed the life cycle issues in focus. A literature search with a life cycle perspective within product development will lead to Concurrent Engineering, and in turn expand the problems with parallel activities in different areas, thereby leading to design conflicts where some sort of trade off is decided upon. The literature describes conceptual engineering design phases as difficult, where knowledge of the design requirements and constraints is usually imprecise and incomplete and where few tools can support this phase.
Work has been done to support the design, manufacturing and analysis processes, though this support normally appears later in the process and not during the earliest phases. As initially discussed, the life cycle issues are of great importance and a conceptual support system addressing these issues needs to be developed.
It was found during the literature study that most decision support system focused on one or two disciplines. By addressing life cycle issues, more disciplines need to be considered. A flange design application was created to show the advantage of involving more disciplines. The flange is a suitable mechanical element since it works as an interface between the jet engine components making its design affect performance, manufacturing and maintenance issues.
8 Knowledge Enabled Engineering Approach
KEE includes KBE and other knowledge rich strategies [32], and aims to support or perform engineering activities with the help of available techniques and methods.
The purpose of KEE is to allow automation of engineering work. The presented KEE approach embeds methods used downstream to simulate effects and render information not readily available early on. KEE is here described with three components: capture of engineering knowledge, automation of engineering activities and quality control of engineering activities. KEE and KBE are similar in how they are used for automating engineering activities, though KBE is often closely associated with commercial computer aided systems providing demand driven, object oriented programming languages.
8.1 Capture of Engineering Knowledge
Knowledge from many disciplines needs to be captured and managed within
engineering design. The capture of engineering knowledge is not easily performed,
as the knowledge exists in a number of disciplines from business to maintenance activities. A number of modelling techniques, Table 1, have been used to capture, support or automate different engineering activities. No technique will capture all aspects within the engineering domain. Instead, the KEE approach supports the use of the best-suited technique for each knowledge asset. It is important to allow a continuous improvement where lessons learned are incorporated into the model of knowledge.
8.2 Automation of Engineering Activities
This phase is usually done simultaneously with the capturing of knowledge. It is an iterative process between the capturing of engineering knowledge and the automation of the engineering activities. The latter is considered a vital part of the KEE approach and allows fast iteration of engineering activities in the early phases to extract knowledge not normally available. The choices made can then be tested allowing engineers to design the life cycle properties of the product.
8.3 Quality Control of Engineering Activities
If the process is captured in a computerized system, it can be replicated each time. Several hundred concepts can then be created when the process to generate and evaluate them is the same. This quality assurance provides engineers a reliable basis from where to compare concepts. A captured process is now an asset of the company and can be reused whenever needed.
9 Case Description, Analysis and Results
In the participatory action research, the case created inside a company’s own process consists of suitable actions to conduct research on. By arranging the case in the actual product development process, those to be helped in the process determine the purposes and outcomes of their own inquiry [31]. A case to support a flange design process was chosen as it involves design, manufacturing and maintenance aspects.
9.1 Flange design process
A rotational symmetric flange joint constitutes an important function within jet
engines, acting as an interface or link between different parts. It transfers loads
while keeping the engine free from leakage. The bolts used in the flange joint have
to keep the joint tight during engine operation. As always in design projects, several
disciplines are involved to create a product. Factors to be considered when
designing a new bolt connection are loads, leakage and accessibility. The leakage
problem is also dependent on the surface roughness between the two joining
flanges, which in turn is dependent on the manufacturing process. The flange
geometry is not only determined by geometrical restrictions from the surrounding
components, but also on the flange being easy to assemble and maintain. One can
quickly see that these areas are interlinked, see the example in Figure 2.
Sealing requirements -Surface roughness
Geometric Dimensions
Loads Loads
Torque Requirement
• Manufacturing Req.
• Performance Req.
• Maintenance Req.
Easy to assemble Sealing requirements
-Surface roughness
Geometric Dimensions
Loads Loads
Torque Requirement
• Manufacturing Req.
• Performance Req.
• Maintenance Req.
Easy to assemble
Figure 2. Section of a circular flange with its requirements and loads.
The figure also shows requirements to design the bolt connections flanges to fulfil all demands and safety criteria.
9.2 Flange Design Application
Paper A describes how the flange design application is created. The application is controlled via a main interface, Figure 3, where the user can specify the type of flange, manufacturing methods, type of material and flange dimensions. Figure 4 show a topological change where the user can add or remove a heel from the flange geometry through this main interface. By pushing the analysis button a new interface permits the user to dimension either the flange or the bolt. Figure 5 shows the bolt dimension interface. As seen in the picture the application alerts the user if the effective stress is too high and gives some directive to either chose a bigger bolt or change bolt material. Another solution is to change the actual flange geometry.
By pushing the button manufacturing properties, an interface appears allowing the
user to choose between facing properties and drilling properties. The interface in
Figure 6 appears when the facing properties button is chosen. In this interface the
user can specify planar tolerance requirements on the surfaces indicated in the
interface figure as well as the surface roughness. The time for the facing operation is
then automatically calculated and presented in the interface. A drilling properties
interface appears when the drilling properties button is chosen, Figure 7. The
drilling time is calculated depending on the number of holes and tolerances. Figure
8 shows the maintenance interface that appears by pushing the manufacturing
properties button in the main interface. From this maintenance interface assemble
and bolt cost is presented.
Figure 3. Main user interface of the KBE application in UG.
Figure 4. A topological change is made where the user removed the heel from the flange geometry.
Figure 5. The application alerts if the chosen bolt is unsuitable.
Figure 6. Facing evaluation.
Figure 7. Drilling evaluation.
Figure 8. Maintenance properties.
With the help of the user interface, the flange design engineer can quickly perform the dimension process of the flange and evaluate a number of configuration alternatives from a performance, manufacturing and maintenance perspective. Figure 9 shows how the flange design application has been used to create a flange for the jet engine component. A toggle in the main interface’s white box generates a cost report in the lower right hand corner of Figure 9.
Figure 9. The flange KEE application coupled to an engine component. The cost report is
shown in the lower right hand corner.
9.3 A common life cycle view
Paper B shows how the flange design application can be used to rapidly extract life cycle cost data and compare different scenarios with or without any component change. Figure 10 shows how the different bolt dimensions and material choices affect normalized life cycle cost. Figure 11 compares the normalized life cycle cost due to choice of surface roughness and normalized facing cost.
0 0,2 0,4 0,6 0,8 1
M14_D40 M8_D40 M5_D40 Bolt dimension
Normalized life-cycle cost
No component change Component change
0 0,2 0,4 0,6 0,8 1
Aluminium Titanium Material
Normalized life-cycle cost
No component change Component change
Figure 10. Normalized life-cycle cost due to surface roughness choice (left) and normalized facing cost.
0 0,2 0,4 0,6 0,8 1
extremely heavy roughing
extreme finishing Surface roughness
Normalized life-cycle cost
No component change Component change
0 0,2 0,4 0,6 0,8 1
extremely heavy roughing
extreme finishing
Surface roughness
Normalized facing cost
Steel Titanium
Figure 11. Normalized life-cycle cost due to surface roughness choice (left) and normalized facing cost.
9.4 Analysis
Papers A and B shows how downstream activities can be modelled and thereby
provide a direct response as to what effects conceptual choices made will have on
the life cycle cost. In this KEE application the manufacturing method, tolerance and
surface finish along with the correct manufacturing and maintenance process
numbers can be altered, providing the engineer a direct response of how much the
chosen method, tolerance, etc., will affect the manufacturing and maintainability
costs. When developing the product in a traditional manner, these aspects are not
seen until the product specification or geometry reaches the production and
maintenance departments. The results show how the application can present a
common view to the participating disciplines, thus preventing design conflicts due
to changes of bolts, material and surface roughness. Since the engineer can change
the design and directly assess the life-cycle cost, more knowledge on the impact of
design decisions is available than without the application. This kind of KEE application will allow simulation of the product life cycle to predict the operative cost. Early knowledge about the operative cost will be the key factor in strategic decisions for business cases such as total offers.
10 Summary of papers
10.1 PAPER A
Boart P., Sandberg M., Nergård H., Isaksson O.
A knowledge enabled engineering approach for conceptual design of life cycle properties.
Submitted for publication in the Journal of Computing and Information Science in Engineering, JCISE.
10.1.1 Summary
Aerospace business agreements are being made on a life cycle basis where the actual product ownership often remains with the manufacturer. Revenue for aero engine manufacturers and their engine programs appear late in the engine life cycle, not during market introduction when large discounts are common. An engine developed for the sale of spare parts is not optimized for the owner. The key when owning and producing engines is to develop engines with a minimum life cycle cost.
The application presented in this paper shows how downstream activities can be modelled using KEE, as demonstrated by conceptualization of a circular flange with different performance and life cycle requirements. This will allow engineers to perform less routine work and optimize their time with life cycle properties. In this KEE application the manufacturing method, tolerance and surface finish along with the correct manufacturing and maintenance process number can be altered, providing the engineer a direct response of how much the chosen method, tolerance, etc., will affect the manufacturing and maintainability costs. When developing the product in a traditional manner, these aspects are not seen until the product specification or geometry reaches the production and maintenance departments. This kind of KEE application will allow simulation of the product life cycle to predict the operative cost. Early knowledge about the operative cost will be the key factor in strategic decisions for business cases such as total offers.
10.2 PAPER B
Sandberg, M., Boart, P., Larsson, T.
Product life-cycle simulation application for cost estimation and conflict prevention in conceptual design of jet-engine components.
Submitted for publication in the journal Concurrent Engineering: Research and Applications, CERA.
10.3 Summary
Assessing the product life-cycle cost during the early stages of product
development is vital in making good design decisions. Since functional (total care)
products are emerging in the jet engine industry, the need for product life-cycle
models increases as functional products include both hardware and service development. Recent life-cycle models often concentrate on estimating design and manufacturing activities, which explains why building life-cycle models that also include other parts of the product life-cycle is needed, like maintenance and recycling. The aim with this paper is to present an approach to simulate the product life-cycle in terms of more disciplines than design and manufacturing, for cost estimation support in development of the hardware part of functional product concepts. Knowledge enabled engineering (KEE), an approach including knowledge intensive methods, was used to develop a case study application in cooperation with a jet engine component manufacturer. Aspects considering design, manufacturing, performance and maintenance of jet engine flanges were included in the application by means of a KBE-system coupled to databases and spreadsheets, resulting in, e.g.
the prevention of design conflicts as well as life-cycle cost variations due to changes of bolts, material and surface roughness. The application is more suitable than recent work to develop the hardware part of functional products, as knowledge from more product development disciplines is included. Because the engineer can change the design and directly assess the life-cycle cost, more knowledge regarding the impact of design decisions is available than without the application.
11 Conclusions
The developed method describes a way to support the evaluation of a concept by simulating life cycle aspects of product solutions and thereby customized business solutions.
It is shown:
• How a decisions support system can be used to capture downstream knowledge from design, manufacturing and maintenance activities, thereby allowing life cycle effects to be simulated already in the conceptual phase.
• How engineers can change the design and directly assess the life cycle cost already in the conceptual phase, allowing fast iterations and thereby design the life cycle of a product based on knowledge from design, manufacturing and maintenance disciplines.
12 Discussions
In an attempt to answer the research question, it was realized that the decisions
made during the design process would form the life cycle properties and in
particular those made early on. The research question was formulated with the
desire to allow the life cycle of the product to be simulated. If this would be possible,
engineers would be provided with a tool to extract knowledge about how their
decisions affect the life cycle of the product. The application developed show how
normally inaccessible knowledge in the conceptual phase could be extracted by
simulation of engineering activities like performance, manufacturing and
maintenance activities. Not only can the captured activities be performed faster,
they could also be replicated each time, with the KEE application being described if
one would like to know how the process is performed.
A captured activity assures that it will be replicated each time and allow for fast conceptual decision-making even if people transferred to other activities. When all activities needed to evaluate life cycle properties are captured, the opportunity to optimize the life cycle appears. Capturing activities from design, manufacturing, maintenance and sales will allow an optimization to be performed on a higher level, leaving sub optimization in separate disciplines to later phases. Downstream activities captured into a support system will also allow fast interaction in a distributed and global product development process. Knowledge and information normally received later in the process can now be distributed earlier, giving new opportunities in a common business-to-business process. Optimization in a global perspective will allow for the right decision-making early on with a clear understanding of how life cycle issues are affected by the choices made.
The KEE application created in Paper A has not yet been developed to that extent that it can be used in the actual flange design process. Still, it shows how activities within the actual flange design process can be captured and presented. The work actually shows that life cycle properties are already possible to simulate in the conceptual design phase. The research done here strongly demonstrates the possibilities with these systems, while any industry not taking the opportunity to learn using them will face a difficult future with extremely short product development lead-times for optimized products.
13 Future Work
Numerous companies participate in the development process of jet engines. To
allow support systems to be developed together with other companies a number of
issues needs to be addressed. Future research will focus on supporting this common
development process between companies and develop the required methods and
applications.
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A knowledge enabled engineering approach
for conceptual design of life cycle properties.
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design of life cycle properties
Patrik Boart
Division of Computer Aided Design
Department of Applied Physics and Mechanical Engineering
Luleå University of Technology SE-971 87 Luleå, Sweden E-mail: patrik.boart@ltu.se
Marcus Sandberg
Division of Computer Aided Design
Department of Applied Physics and Mechanical Engineering
Luleå University of Technology SE-971 87 Luleå, Sweden E-mail: marcus.sandberg@ltu.se Henrik Nergård
Division of Computer Aided Design
Department of Applied Physics and Mechanical Engineering
Luleå University of Technology SE-971 87 Luleå, Sweden E-mail: henrik.nergard@ltu.se
Ola Isaksson
Advanced Design Engineering Volvo Aero Corporation SE-461 81 Trollhättan, SWEDEN E-mail: ola.isaksson@volvo.com
1 Abstract
Aerospace business agreements are being made on a life cycle basis where the actual product ownership often remains with the manufacturer. The aim of this paper is to examine the possibility to conceptualize life cycle properties in a commercial engineering design system. A flange design process is chosen as a case study. To support the process a generative model is used to extract downstream knowledge from activities in different disciplines and allow simulation of life cycle properties. The model will be used for strategic decisions when developing total offers.
Keywords: Knowledge Enabled Engineering, Aerospace, Manufacturability, Concept design, Engineering Design
2 Introduction
Business to business cooperation is undergoing large changes that closely fits the transformational driving forces, for example those identified by Swedish Technology Foresight on future product systems 2015 [1].
x Individuals and companies act on local as well as global markets.
x Circular business systems: closed resource flows and scale of functions.
x Intellectual capital is the most important means of competition.
x Complexity in upcoming systems is leading to new demands.
Page 2 (18)
to develop products in business to business relations. This will force companies to optimize their part of the product system relating to the total product system. Aerospace business agreements are being made on a life cycle basis where the actual product ownership often remains with the manufacturer. The revenue for aero engine manufacturers and their engine programs appear late in the engine life cycle, not during market introduction where large discounts are common. An engine developed for the sale of spare parts is not optimized for the owner. The key when owning and producing engines is to develop engines with minimum life cycle cost.
Few support tools exist for the conceptual phase in engineering product development [2]. A company is therefore dependent on experienced personnel to make the right decisions. An aircraft engine is a rather complex product involving many disciplines during development.
Conceptualizing products consisting of hardware, software and services during the life cycle is a rather demanding task with little time usually being spent during the conceptual phase.
Improved system support is needed in the conceptual phase to handle the increase of information in future products. Limited knowledge about the product’s life cycle exists in the conceptual phase, though important decisions affecting the cost of the life cycle are still made here. A need to simulate what effects the choices made have on the product life cycle has risen because aerospace business agreements are being made on life cycle basis.
Capturing an activity from a product development process into a computerized support system allows it to be performed automatically. The knowledge within the captured activity can then be extracted and used where needed. It becomes possible with such a system to simulate events further down in the product’s life cycle (downstream knowledge) in the early design phases where costs are committed, providing better control of the products life cycle cost and an increased accuracy when estimating eventual profit.
The aim of this paper is how to conceptualize life cycle properties in a commercial engineering design system for a company in a business to business environment selling a total offer [3] instead of hardware.
The study shows how design variables needed to evaluate the product life cycle effects can be captured in a commercial engineering design system. This is be demonstrated on a jet engine component flange with different performance and life cycle requirements. The article commences with a review of related work with tools created to support different activities within the area of engineering design, followed by an explanation of the Knowledge
Enabled Engineering approach. A description of a flange design process is then given where design, manufacturing, maintenance and cost report knowledge are captured and formalized.
From the formalized knowledge, the structure of the application can then be built and coded.
A demonstration of the final Knowledge Enabled Engineering application is given at the
end.
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Best practice in Engineering Design (ED) is continuously changing. Knowledge Based Systems and especially Knowledge Based Engineering (KBE) Systems are being used more frequently to store knowledge and support design processes [4-7]. Currently, product and process experience are often person dependent [2], where staff turnover causes loss of experience. Another issue is that products become more complex, with development requiring the involvement of more disciplines. These issues force companies to adapt their work practice to better account for multidisciplinary knowledge in the conceptual phase.
Historically, KBE was developed by using principles from Expert Systems technology and CAD systems. Expert Systems coupled to CAD-tools emerged in the 1970s as a way of controlling and evaluating the geometry by means of rules [8]. KBE differed from Expert Systems by supporting tedious and repetitive work rather than expert knowledge reasoning [4]. Some claim that Expert Systems were unsuitable for Engineering Design situations and therefore failed [9]. Furthermore, KBE applications were designed to support both synthesis and analysis activities in the engineering design process.
Companies accumulate knowledge and experience during product development and through the operation of the product. A challenge is to maintain this knowledge and use it
efficiently, while reducing the amount of routine work and release time to increase the space of creative solution exploration. However, how is this done in a company with established design systems? Engineers tend to spend a significant portion of their time creating various geometric models, and since this work is tedious and often rather repetitive in character, it should be a candidate for KBE modeling. The same types of models are often created over and over again containing a minimum of innovation and little re-use of pre-existing know- how [9]. Parametric CAD-models are a way of storing some amount of knowledge, enabling the solid model to be scaled and reused. However, it is difficult to make “traditional”
parametric models that allow topological changes in the geometry. Likewise, it is not obvious how to associate non-geometric design variables to the parametric CAD model.
Expert systems previously tried to solve these issues. A number of knowledge modeling
techniques have been used to support different steps in the product development. An
overview is used to show where and how they have been used, Table 1.
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Technique
