- 282 views
- 273 downloads
The Role of First Order Surface Effects in Linear Elastic Fracture Mechanics
-
- Author / Creator
- KIM, CHUN IL
-
Structures at relatively small scales (e.g. nano/micro scale) behave
differently in comparison to those examined at the macro scale. This is
mainly because a high surface area to volume ratio is present at this scale
making physical factors such as surface stress/energy and electromagnetic
forces much more significant. In particular, ‘surface effects’ induced by a
local environmental change of the region near the surface of solids, greatly
influence the general behavior of the corresponding bulk material especially
when the scale of materials become compatible with the nano/micro scale.
This in turn, suggest that a more accurate and comprehensive description
of the general behavior of an elastic solid with one or more surfaces can be
achieved by incorporating a description of the separate surface mechanics
near each surface of the solid.
In the dissertation, we examine the effects of first-order surface elasticity in
linear elastic fracture mechanics. A complete analysis has been performed
for both plane and anti-plane deformations and for cases in which cracks
are present in a homogeneous material and subsequently in the interface
between two dissimilar elastic materials. It is shown that the introduction
of the effects of first-order surface elasticity results in, in most cases, the
reduction of the stress singularity at the crack tip from the classical strong
square root singularity to a weaker logarithmic singularity. In particular,
the refined model (with first-order surface effects integrated) predicts a
more realistic description of size-dependent stress distributions commonly
existing at the small scale structures. In the case of an interface crack
arising in the interfacial region between two dissimilar materials, the
refined model removes the classical oscillatory behaviors of the
corresponding stress distributions leading again to size-dependent and
stable stresses in the vicinity of the crack. -
- Graduation date
- Fall 2012
-
- Type of Item
- Thesis
-
- Degree
- Doctor of Philosophy
-
- License
- This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.