An important factor in system longevity is service-phase evolvability, which is defined as the ability of a system to physically transform from one configuration to a more desirable configuration while in service. These transformations may or may not be known during the design process, and may or may not be reversible. In a different study, we examined 210 engineered systems and found that system excess and modularity allow a system to evolve while in service. Building on this observation, the present paper introduces mathematical relationships that map a system's excess to that system's ability to evolve. As introduced in this paper, this relationship is derived from elastic potential-energy theories. The use of the evolvability measure, and other related measures presented herein, are illustrated with simple examples and applied to the design of U.S. Navy nuclear aircraft carriers. Using these relationships, we show that the Navy's new Ford-class aircraft carrier is measurably more evolvable than the Nimitz-class carriers. While the ability for systems to evolve is based on excess and modularity, this paper is focused only on excess. The mapping between modularity and evolvability is the focus of another work by the authors.
A Model for Quantifying System Evolvability Based on Excess and Capacity
Brigham Young University,
and Aerospace Engineering,
North Carolina State University,
Contributed by the Design Theory and Methodology Committee of ASME for publication in the JOURNAL OF MECHANICAL DESIGN. Manuscript received May 3, 2013; final manuscript received January 23, 2014; published online March 13, 2014. Assoc. Editor: Jonathan Cagan.
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Tackett, M. W. P., Mattson, C. A., and Ferguson, S. M. (March 13, 2014). "A Model for Quantifying System Evolvability Based on Excess and Capacity." ASME. J. Mech. Des. May 2014; 136(5): 051002. https://doi.org/10.1115/1.4026648
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