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Proceedings Paper

Lifetime estimates for time-dependent properties of materials
Author(s): Harold B. Liemohn; Sam A. Denham; E. C. McKannan
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Paper Abstract

A time-dependent term is introduced into the Arrhenius rate equation to refine the lifetime projections for materials that do not satisfy the linearity assumptions of the theory. This new term describes those materials where properties decay exponentially during the early phase of their exposure to elevated temperatures and subsequently equilibrate to almost constant values. The method is applied to the acoustic-absorber polyimide foam, `Solimide,' resulting in lifetime predictions for specific strength that are believed to be more accurate and reliable than predictions with the linear theory. Furthermore, the entire data set was included in a single nonlinear regression method which assured an orderly temperature dependence and smoothed out uncertainties in the measurements.

Paper Details

Date Published: 7 July 1995
PDF: 11 pages
Proc. SPIE 2455, Nondestructive Evaluation of Aging Aircraft, Airports, Aerospace Hardware, and Materials, (7 July 1995); doi: 10.1117/12.213558
Show Author Affiliations
Harold B. Liemohn, Boeing Defense & Space Group (United States)
Sam A. Denham, Boeing Aerospace & Electronics (United States)
E. C. McKannan, Boeing Defense & Space Group (United States)


Published in SPIE Proceedings Vol. 2455:
Nondestructive Evaluation of Aging Aircraft, Airports, Aerospace Hardware, and Materials
Tobey M. Cordell; Raymond D. Rempt, Editor(s)

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