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Rapid response of a growing environmental craze to a stress pulse
Author(s) -
Conners Andrew,
Kramer Edward J.
Publication year - 1980
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.760200909
Subject(s) - crazing , materials science , composite material , stress (linguistics) , creep , deformation (meteorology) , tension (geology) , strain rate , polymer , compression (physics) , philosophy , linguistics
Double exposure holographic interferometry has been used to measure the response of a growing craze to a pulsed stress. The craze was grown in situ by application of methanol to a crack in a poly (methyl methacrylate) (PMMA) strip under tension ( K 1 = 0.4 MN/m 3/2 ). An incremental stress, approximating 15 percent of the overall crazing stress, is applied to the growing craze in a 1 s pulse. Incremental strain and stress profiles are measured along a line parallel to, but displaced 1.0 mm from, the growing craze, from a double exposure hologram triggered just before and during the pulse. The craze deforms rapidly, relieving the incremental stress concentration that can be shown to exist before craze growth. In a second set of experiments one holographic exposure is triggered during the incremental stress pulse, and a second exposure is triggered afterward. The results of such experiments indicate that the craze deformation is primarily plastic, and corresponds to a plastic strain rate of not less than 0.2 s −1 . Consideration of the diffusion limitation of the rate of craze thickening leads to the conclusion that this plastic deformation is attributable to fibril creep rather than a surface drawing mechanism.