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Environmentally assisted initiation and growth of multiple surface cracks

Hejman, Ulf and Bjerkén, Christina LU (2010) In International Journal of Solids and Structures 47(14-15). p.1838-1846
Abstract
The initial stages of stress corrosion on an amorphous polymer is investigated. This is done by exposing stressed specimens of polycarbonate to an acetone and water solution. The surface develops two distinct features of degradation that appear on different length scales when subjected to tensile stress. Small pits form on the surface and make it rough. These pits are in the order of micrometers, and are found to be randomly distributed. They occur even without load and seem to slightly increase in number with increasing stress. In the millimeter domain, visible to the bare eye, surface cracks are formed transverse to the direction of loading. The occurrence of cracks is seen to have a positive stress threshold value, exceeding which, a... (More)
The initial stages of stress corrosion on an amorphous polymer is investigated. This is done by exposing stressed specimens of polycarbonate to an acetone and water solution. The surface develops two distinct features of degradation that appear on different length scales when subjected to tensile stress. Small pits form on the surface and make it rough. These pits are in the order of micrometers, and are found to be randomly distributed. They occur even without load and seem to slightly increase in number with increasing stress. In the millimeter domain, visible to the bare eye, surface cracks are formed transverse to the direction of loading. The occurrence of cracks is seen to have a positive stress threshold value, exceeding which, a linear increase of number of cracks with stress is found. The manners in which the cracks grow and coalesce on the surface are examined. It is seen that they do not meet crack tip to crack tip. Instead, they avoid each other initially and coalesce crack tip to crack side. The results are discussed in the light of mechanical considerations. A stress analysis for a few configurations of meeting cracks supports the experimental observations. With assumptions of stress corrosion crack growth and coalescence, a simulation of cracks growing from randomly distributed initiation sites is performed. Similar crack patterns as obtained in the experiments are found. (C) 2010 Elsevier Ltd. All rights reserved. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Three point bending, Polycarbonate, Multiple cracking, Stress corrosion, Crack initiation
in
International Journal of Solids and Structures
volume
47
issue
14-15
pages
1838 - 1846
publisher
Elsevier
external identifiers
  • wos:000278280900009
  • scopus:77955229332
ISSN
0020-7683
DOI
10.1016/j.ijsolstr.2010.03.023
language
English
LU publication?
yes
id
c6bb0067-d39a-4b11-bcd1-aa03419ab4d5 (old id 1632179)
date added to LUP
2010-07-21 10:06:11
date last changed
2018-05-29 11:30:06
@article{c6bb0067-d39a-4b11-bcd1-aa03419ab4d5,
  abstract     = {The initial stages of stress corrosion on an amorphous polymer is investigated. This is done by exposing stressed specimens of polycarbonate to an acetone and water solution. The surface develops two distinct features of degradation that appear on different length scales when subjected to tensile stress. Small pits form on the surface and make it rough. These pits are in the order of micrometers, and are found to be randomly distributed. They occur even without load and seem to slightly increase in number with increasing stress. In the millimeter domain, visible to the bare eye, surface cracks are formed transverse to the direction of loading. The occurrence of cracks is seen to have a positive stress threshold value, exceeding which, a linear increase of number of cracks with stress is found. The manners in which the cracks grow and coalesce on the surface are examined. It is seen that they do not meet crack tip to crack tip. Instead, they avoid each other initially and coalesce crack tip to crack side. The results are discussed in the light of mechanical considerations. A stress analysis for a few configurations of meeting cracks supports the experimental observations. With assumptions of stress corrosion crack growth and coalescence, a simulation of cracks growing from randomly distributed initiation sites is performed. Similar crack patterns as obtained in the experiments are found. (C) 2010 Elsevier Ltd. All rights reserved.},
  author       = {Hejman, Ulf and Bjerkén, Christina},
  issn         = {0020-7683},
  keyword      = {Three point bending,Polycarbonate,Multiple cracking,Stress corrosion,Crack initiation},
  language     = {eng},
  number       = {14-15},
  pages        = {1838--1846},
  publisher    = {Elsevier},
  series       = {International Journal of Solids and Structures},
  title        = {Environmentally assisted initiation and growth of multiple surface cracks},
  url          = {http://dx.doi.org/10.1016/j.ijsolstr.2010.03.023},
  volume       = {47},
  year         = {2010},
}