EXECUTIVE SUMMARY

A scientist studies what is, whereas an engineer creates what never was.

Theodore von Karman

Both engineering design and the ability to teach it have been the subject of many meetings, publications, and organizations as well as any number of spirited discussions. Without doubt, the various aspects of this issue can admirably engage both sides of our brains. The Board on Manufacturing and Engineering Design, at the request of the National Science Foundation, established a distinguished committee to examine the theories and techniques for decision making under conditions of risk, uncertainty, and conflicting human values. This report of that committee attempts not only to analyze existing tools but also to identify opportunities to establish a more rigorous fundamental basis for decision making in engineering design. The specific tasks were to as follows:

  • Identify the strengths and limitations of tools currently used in engineering design as they relate to decision making and issues of risk and values in the increasingly complex manufacturing climate described in Visionary Manufacturing Challenges for 2020 (NRC, 1998) and other recent studies. This will include such methodologies as design for manufacture, Taguchi’s theory of robust design, Quality Function Deployment, and concurrent engineering.

  • Identify approaches to decision making in other fields, such as operations research, economics, and management sciences, that address issues of risk and value. This will include a review of the state of the art and the extent of validation of these theories. The committee was also charged to investigate the pertinence and validity of these approaches for building an improved decision-making framework for engineering design that can rigorously deal with probability, preferences, and risk in the manufacturing climate of 2020.

The committee reviewed previous studies about decision making in engineering design, consulted with a cross section of engineering design leaders in industry and academia, and listened to invited speakers. Based on this information and the knowledge and experience of committee members, the committee makes four recommendations:

Recommendation. Constructive dialogue should be encouraged to allow the best aspects of each method and theory for decision making in engineering design to be incorporated into common practice. Sponsored academic research could be used as a mechanism to assist integration of existing theories and development of new ones. Workshops or other cooperative ventures should be held in which experts establish engineering design tools that could evolve into common practice. The ease of use and practicality of these solutions should be paramount.

Recommendation. More research should be focused on enhancing design tools and methods applicable to all engineering disciplines. The increasing complexity of physical systems, as well as software and biological and medical systems, begs for increasingly quantitative and transparent tools for making and justifying design decisions. Research for designers to develop appropriate knowledge bases is required. The many gaps isolating related tools and theories must be bridged and a taxonomy to facilitate comparisons between approaches must be created.

Recommendation. Statistics and probability should be required and incorporated into the undergraduate engineering curriculum to emphasize their relevance to engineering design and decision making, process control, and product testing.



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Theoretical Foundations for Decision Making in Engineering Design EXECUTIVE SUMMARY A scientist studies what is, whereas an engineer creates what never was. —Theodore von Karman Both engineering design and the ability to teach it have been the subject of many meetings, publications, and organizations as well as any number of spirited discussions. Without doubt, the various aspects of this issue can admirably engage both sides of our brains. The Board on Manufacturing and Engineering Design, at the request of the National Science Foundation, established a distinguished committee to examine the theories and techniques for decision making under conditions of risk, uncertainty, and conflicting human values. This report of that committee attempts not only to analyze existing tools but also to identify opportunities to establish a more rigorous fundamental basis for decision making in engineering design. The specific tasks were to as follows: Identify the strengths and limitations of tools currently used in engineering design as they relate to decision making and issues of risk and values in the increasingly complex manufacturing climate described in Visionary Manufacturing Challenges for 2020 (NRC, 1998) and other recent studies. This will include such methodologies as design for manufacture, Taguchi’s theory of robust design, Quality Function Deployment, and concurrent engineering. Identify approaches to decision making in other fields, such as operations research, economics, and management sciences, that address issues of risk and value. This will include a review of the state of the art and the extent of validation of these theories. The committee was also charged to investigate the pertinence and validity of these approaches for building an improved decision-making framework for engineering design that can rigorously deal with probability, preferences, and risk in the manufacturing climate of 2020. The committee reviewed previous studies about decision making in engineering design, consulted with a cross section of engineering design leaders in industry and academia, and listened to invited speakers. Based on this information and the knowledge and experience of committee members, the committee makes four recommendations: Recommendation. Constructive dialogue should be encouraged to allow the best aspects of each method and theory for decision making in engineering design to be incorporated into common practice. Sponsored academic research could be used as a mechanism to assist integration of existing theories and development of new ones. Workshops or other cooperative ventures should be held in which experts establish engineering design tools that could evolve into common practice. The ease of use and practicality of these solutions should be paramount. Recommendation. More research should be focused on enhancing design tools and methods applicable to all engineering disciplines. The increasing complexity of physical systems, as well as software and biological and medical systems, begs for increasingly quantitative and transparent tools for making and justifying design decisions. Research for designers to develop appropriate knowledge bases is required. The many gaps isolating related tools and theories must be bridged and a taxonomy to facilitate comparisons between approaches must be created. Recommendation. Statistics and probability should be required and incorporated into the undergraduate engineering curriculum to emphasize their relevance to engineering design and decision making, process control, and product testing.

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Theoretical Foundations for Decision Making in Engineering Design Recommendation. Decision-making tools and decision theory should be included in a required undergraduate design course. Interdisciplinary capstone courses that include legal, social, and economic issues, as well as team building skills, can be particularly useful teaching tools and should be included in this undertaking. Table ES–1 compares and contrasts the various decision-making tools examined in this report. The summary in Chapter 4 provides an explanation of the details presented here. Table ES–1 Summary of Tools and Applications Examined   Primary Basis Ratingsa—Potential Value for:   Knowledge Engineering Logic/Set Theory Matrix Algebra Probability Statistics Economics Current Utilization Concept Creation Concept Development Selection Among Alternative Concepts Ease of Use Practical Concurrent Engineering   X 4 2 4 4 1 Qualitative Decision Matrix   X   X 4 1 2 4 5   Pugh Method   X   3 4 5 1 2   QFD   X   2 2 4 2 1   AHP   X   3 1 2 4     Product Plan Advisor X   X X   3 2 3 4 3 Statistical PLS   X X   1 3 3 2 1   Taguchi Method   X X   4 1 4 4 2   Six Sigma   X X   3 3 3 3 2 Creative AI Support X   2 4 2 2 2   TRIZ X   3 3 1 1 3 Axiomatic Suh’s Theory   X X   2 2 3 5 1   Yoshikawa Theory   X   1 1 1 1 1   Math Framework   X   X X X 1 1 1 5 3 Validating Game Theory   X   X 1 1 1 3 2   Decision Analysis   X   X   X 3 1 4 5 3 aRating by several members of the committee: 1=low; 5=high. Decision-making tools can be useful design aids when appropriately applied. However, because the knowledge embodied in a designer or design team to synthesize and create is uniquely human, design cannot ever be totally automated. Decision tools and many other methods can aid the design process by organizing knowledge and providing systematic frameworks to enable the designer to generate new options and make intelligent choices to realize a product. The design community can make progress only when engineering design decision’s are understood from the perspective of stakeholders in manufacturing enterprises and society. Time, effort, and resources must be invested

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Theoretical Foundations for Decision Making in Engineering Design in understanding engineering design as it is practiced, in creating a taxonomy to facilitate communication among the stakeholders and participants, and then in identifying what needs to be done to move forward. The committee was divided on the value of developing the theoretical foundations for decision making in design. An additional recommendation, advocated by some members, would be to focus federal efforts on the development of a validated mathematical framework for decision making in engineering design. Other members felt that the rapidly changing design space and the tools to address it make this approach impractical. The committee did not reach consensus on this point REFERENCE National Research Council. 1998. Visionary Manufacturing Challenges for 2020. Washington D.C.: National Academy Press.