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An Investigation of High-Cycle Fatigue Models for Metallic Structures Exhibiting Snap-Through ResponseA study is undertaken to develop a methodology for determining the suitability of various high-cycle fatigue models for metallic structures subjected to combined thermal-acoustic loadings. Two features of this problem differentiate it from the fatigue of structures subject to acoustic loading alone. Potentially large mean stresses associated with the thermally pre- and post-buckled states require models capable of handling those conditions. Snap-through motion between multiple post-buckled equilibrium positions introduces very high alternating stress. The thermal-acoustic time history response of a clamped aluminum beam structure with geometric and material nonlinearities is determined via numerical simulation. A cumulative damage model is employed using a rainflow cycle counting scheme and fatigue estimates are made for 2024-T3 aluminum using various non-zero mean fatigue models, including Walker, Morrow, Morrow with true fracture strength, and MMPDS. A baseline zero-mean model is additionally considered. It is shown that for this material, the Walker model produces the most conservative fatigue estimates when the stress response has a tensile mean introduced by geometric nonlinearity, but remains in the linear elastic range. However, when the loading level is sufficiently high to produce plasticity, the response becomes more fully reversed and the baseline, Morrow, and Morrow with true fracture strength models produce the most conservative fatigue estimates.
Document ID
20070018035
Acquisition Source
Langley Research Center
Document Type
Conference Paper
Authors
Przekop, Adam (National Inst. of Aerospace Hampton, VA, United States)
Rizzi, Stephen A. (NASA Langley Research Center Hampton, VA, United States)
Sweitzer, Karl A. (ITT Corp. Rochester, NY, United States)
Date Acquired
August 23, 2013
Publication Date
January 1, 2007
Subject Category
Structural Mechanics
Report/Patent Number
AIAA Paper 2007-2204
Funding Number(s)
WBS: WBS 599489.02.99.01.07
Distribution Limits
Public
Copyright
Public Use Permitted.

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