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Sideways and stable crack propagation in a silicone elastomer
- Source :
- Proceedings of the National Academy of Sciences. 116:9251-9256
- Publication Year :
- 2019
- Publisher :
- Proceedings of the National Academy of Sciences, 2019.
-
Abstract
- We have discovered a peculiar form of fracture that occurs in a highly stretchable silicone elastomer (Smooth-On Ecoflex 00-30). Under certain conditions, cracks propagate in a direction perpendicular to the initial precut and in the direction of the applied load. In other words, the crack deviates from the standard trajectory and instead propagates perpendicular to that trajectory. The crack arrests stably, and thus the material ahead of the crack front continues to sustain load, thereby enabling enormous stretchabilities. We call this phenomenon "sideways" and stable cracking. To explain this behavior, we first perform finite-element simulations that demonstrate a propensity for sideways cracking, even in an isotropic material. The simulations also highlight the importance of crack-tip blunting on the formation of sideways cracks. Next, we provide a hypothesis on the origin of sideways cracking that relates to microstructural anisotropy (in a nominally isotropic elastomer). To substantiate this hypothesis, we transversely prestretch samples to various extents before fracture testing, as to determine the influence of microstructural arrangement (chain alignment and strain-induced crystallization) on fracture energy. We also perform microstructural characterization that indicates that significant chain alignment and strain-induced crystallization indeed occur in this material upon stretching. We conclude by characterizing how a number of loading conditions, such as sample geometry and strain rate, affect this phenomenon. Overall, this paper provides fundamental mechanical insight into basic phenomena associated with fracture of elastomers.
- Subjects :
- Multidisciplinary
Materials science
Isotropy
Fracture mechanics
02 engineering and technology
Strain rate
021001 nanoscience & nanotechnology
Elastomer
Cracking
020303 mechanical engineering & transports
0203 mechanical engineering
Physical Sciences
Perpendicular
Fracture (geology)
Composite material
0210 nano-technology
Anisotropy
Subjects
Details
- ISSN :
- 10916490 and 00278424
- Volume :
- 116
- Database :
- OpenAIRE
- Journal :
- Proceedings of the National Academy of Sciences
- Accession number :
- edsair.doi.dedup.....44ae008122f4cffd37b119e8576af464