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Mixed‐mode subcritical crack growth in orthotropic polymers
Author(s) -
Wu Chunhui,
Mantell Susan C.,
Davidson Jane H.
Publication year - 2008
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.21166
Subject(s) - orthotropic material , materials science , shearing (physics) , composite material , bridging (networking) , extrusion , polymer , fracture mechanics , orientation (vector space) , crack closure , structural engineering , geometry , mathematics , computer network , finite element method , computer science , engineering
A semi‐empirical model of mixed‐mode sub‐critical crack propagation is presented for orthotropic polymers subjected to continuous loading. The model considers a combination of opening and shearing propagation modes. Optical measurement of crack propagation in an orthotropic liquid crystalline polymer film for orientation angles, which define the orientation of the loading to the extrusion direction, of 45 and 90° provides the empirical constants required by the model. The model is validated by comparison of predicted and measured crack propagation at 30, 60, and 75°. The impact of orientation angle on crack propagation is significant. A critical angle is identified at which the crack propagation rates for the opening and shearing modes are equivalent. For orientation angles less than the critical angle the crack growth is dominated by the shearing mode. For orientation angles greater than the critical angle, the crack growth is dominated by the opening mode. For the liquid crystalline polymer film tested, the critical angle is 52.6°. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers