ABSTRACT
CONTACT MECHANICS OF GRADED MATERIALS WITH TWODIMENSIONAL
MATERIAL PROPERTY VARIATIONS
Gö / kay, Kemal
M.S., Department of Mechanical Engineering
Supervisor: Asst. Prof. Dr. Serkan Dag
September 2005, 62 pages
Ceramic layers used as protective coatings in tribological applications are known to
be prone to cracking and debonding due to their brittle nature. Recent experiments
with functionally graded ceramics however show that these material systems are
particularly useful in enhancing the resistance of a surface to tribological damage.
This improved behavior is attributed to the influence of the material property
gradation on the stress distribution that develops at the contacting surfaces. The main
interest in the present study is in the contact mechanics of a functionally graded
surface with a two &ndash / dimensional spatial variation in the modulus of elasticity.
Poisson&rsquo / s ratio is assumed to be constant due to its insignificant effect on the contact
stress distribution [30]. In the formulation of the problem it is assumed that the
functionally graded surface is in frictional sliding contact with a rigid flat stamp.
Using elasticity theory and semi-infinite plane approximation for the graded medium,
the problem is reduced to a singular integral equation of the second kind. Integral
equation is solved numerically by expanding the unknown contact stress distribution
into a series of Jacobi polynomials and using suitable collocation points. The
developed method is validated by providing comparisons to a closed form solution
derived for homogeneous materials. Main numerical results consist of the effects of
the material nonhomogeneity parameters, coefficient of friction and stamp size and
location on the contact stress distribution.
| Identifer | oai:union.ndltd.org:METU/oai:etd.lib.metu.edu.tr:http://etd.lib.metu.edu.tr/upload/12606527/index.pdf |
| Date | 01 September 2005 |
| Creators | Gokay, Kemal |
| Contributors | Dag, Serkan |
| Publisher | METU |
| Source Sets | Middle East Technical Univ. |
| Language | English |
| Detected Language | English |
| Type | M.S. Thesis |
| Format | text/pdf |
| Rights | To liberate the content for public access |
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