Four Alternative Definitions of the Fuzzy Safety Factor
Publication: Journal of Aerospace Engineering
Volume 19, Issue 4
Abstract
The concept of safety factor is nearly universally applied in structural engineering. There are presently several approaches for probabilistic interpretation of the safety factors in the literature. Herein we generalize the above approaches to derive four possible definitions of safety factor that are based on fuzzy sets: (1) the central fuzzy safety factor is defined as the ratio of the centroid abscissas of the membership functions, respectively, of the capacity and the demand of the structure; (2) the characteristic value of fuzzy safety factor as the lower bound of the cut of the fuzzy safety factor for a specified level of the membership function; (3) the mean value of fuzzy safety factor as the centroid abscissa of the fuzzy capacity-to-demand ratio; and (4) the fuzzy multiplicative safety factor is defined as the abscissa of the centroid of the capacity multiplying to the abscissa of the centroid of the inverse of the demand. Fundamental problem of the strength of materials, namely, tension of an element subjected to an axial load, is analyzed in the context of the above four fuzzy safety factors.
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Acknowledgments
I.E. acknowledges partial financial support of the J. M. Rubin Foundation at the Florida Atlantic University. B.F. appreciates the financial support of University of Bologna (R.F.O.-ex 60% grant) and of Florida Atlantic University, Department of Mechanical Engineering. This paper is dedicated to Dr. Ahmed K. Noor who significantly contributed to the introduction of fuzzy sets in engineering (see, for example Noor et al. 2000, 2001, Wasfy and Noor 1998a,b; Abdel-Tawab and Noor 1999).
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Published In
Journal of Aerospace Engineering
Volume 19 • Issue 4 • October 2006
Pages: 281 - 287
Copyright
© 2006 ASCE.
History
Received: Jul 29, 2005
Accepted: Apr 11, 2006
Published online: Oct 1, 2006
Published in print: Oct 2006
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