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Non-Classical Stress Concentration Behavior in a Radically Stretched Hyperelastic Sheet Containing a Circular Hole
NTRS Full-Text: Click to View  [PDF Size: 2.8 MB]
Author and Affiliation:
Ko, William L.(NASA Armstrong Flight Research Center, Edwards, CA United States)
Lung, Shun-Fat(Jacobs Technology, Inc., Edwards AFB, CA, United States)
Abstract: Non-classical stress concentration behavior in a stretched circular hyperelastic sheet (outer radius b = 10 in., thickness t = 0.0625 in.) containing a central hole (radius a = 0.5 in.) was analyzed. The hyperelastic sheet was subjected to different levels of remote radial stretchings. Nastran large-strain large-deformation analysis and the Blatz-Ko large deformation theory were used to calculate the equal-biaxial stress concentration factors K. The results show that the values of K calculated from the Blatz-Ko theory and Nastran are extremely close. Unlike the classical linear elasticity theory, which gives the constant K = 2 for the equal-biaxial stress field, the hyperelastic K values were found to increase with increased stretching and can exceed the value K = 6 at a remote radial extension ratio of 2.35. The present K-values compare fairly well with the K-values obtained by previous works. The effect of the hole-size on K-values was investigated. The values of K start to decrease from a hole radius a = 0.125 in. down to K = 1 (no stress concentration) as a shrinks to a = 0 in. (no hole). Also, the newly introduced stretch and strain magnification factors {K(sub ?),K(sub e) } are also material- and deformation-dependent, and can increase from linear levels of {1.0, 4.0} and reaching {3.07, 4.61}, respectively at a remote radial extension ratio of 2.35.
Publication Date: Aug 01, 2017
Document ID:
20170008001
(Acquired Aug 29, 2017)
Subject Category: AERONAUTICS (GENERAL); STRUCTURAL MECHANICS
Report/Patent Number: NASA/TM-2017-219527, AFRC-E-DAA-TN40409
Document Type: Technical Report
Contract/Grant/Task Num: NND08RR01B
Financial Sponsor: NASA Armstrong Flight Research Center; Edwards, CA United States
Organization Source: NASA Armstrong Flight Research Center; Edwards, CA United States
Description: 33p; In English
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: Copyright; Distribution as joint owner in the copyright
NASA Terms: AXIAL STRESS; DEFORMATION; ELASTIC PROPERTIES; HOLE GEOMETRY (MECHANICS); STRESS DISTRIBUTION; STRESS CONCENTRATION; ELASTIC SHEETS; POISSON RATIO; STRUCTURAL FAILURE; TENSILE STRESS
Other Descriptors: STRESS CONCENTRATION; DISPLACEMENT THEORY
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