The Contradiction Index (CI): A New Metric Combining System Complexity and Robustness for Early Design Stages

Simon Moritz Göhler, Thomas J. Howard

Research output: Chapter in Book/Report/Conference proceedingArticle in proceedingsResearchpeer-review

Abstract

For complex and integrated products, companies experience difficulties in achieving a satisfactory and consistent functional performance. When a design has “contradicting” parameter/property requirements it often requires fine tuning with numerous design iterations and complex optimizations to find the “sweet spot” where all functional requirements are fulfilled. This often leads to a lack of robustness, where tight tolerances are required and small defects have knock-on effects throughout the product. In this article we propose the Contradiction Index (CI) to gauge how contradicting the requirements of the different parts are with respect to the different functions. This article provides a step-by-step guide for how to estimate the CI for a design. The method is applied to a case study - the FlexTouch®, a Novo Nordisk insulin injection device. When analyzing the CI for each part, against the number of part design iterations, a positive correlation was found. Furthermore, when correlating the CI against the number of challenging tolerances statistical significance was found (p=0.01). It is envisaged that the CI will be a powerful approach to estimate and compare development difficulty and to guide development and design improvements.
Original languageEnglish
Title of host publicationProceedings of the ASME 2015 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference IDETC/CIE 2015
Number of pages10
PublisherAmerican Society of Mechanical Engineers
Publication date2015
Article numberDETC2015-47255
Publication statusPublished - 2015
EventASME 2015 International Design Engineering Technical Conferences & Computers and Information in Engineering Conference - Boston, United States
Duration: 2 Aug 20155 Aug 2015
http://www.asmeconferences.org/IDETC2015/

Conference

ConferenceASME 2015 International Design Engineering Technical Conferences & Computers and Information in Engineering Conference
CountryUnited States
CityBoston
Period02/08/201505/08/2015
Internet address

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