Three Dimensional Modeling of Inclined Surface Cracks in FGM Coatings

Kosker S., DAĞ S., YILDIRIM B.

10th International Symposium on Multiscale, Multifunctional and Functionally Graded Materials, Sendai, Japan, 22 - 25 September 2008, pp.109-110 identifier identifier

  • Publication Type: Conference Paper / Full Text
  • Doi Number: 10.4028/
  • City: Sendai
  • Country: Japan
  • Page Numbers: pp.109-110
  • Keywords: Functionally Graded Materials (FGMs), Semi-Elliptical Surface Crack, Finite Element Method, Displacement Correlation Technique, Thermal Stresses
  • Middle East Technical University Affiliated: Yes


This study presents a three dimensional finite element method for mixed-mode fracture analysis of an FGM coating-bond coat-substrate structure. The FGM coating is assumed to contain an inclined semi-elliptical crack at the free surface. The trilayer structure is examined under the effect of transient thermal stresses. Strain singularity around the crack front is simulated by utilizing collapsed wedge-shaped singular elements. The modes I, II and III stress intensity factors are computed by applying the displacement correlation technique and presented as a function of time. Four different FGM coating types are examined in the parametric analyses which are metal-rich, ceramic-rich, linear variation and homogeneous coatings. The results provided illustrate the influences of the FGM coating type and crack inclination angle on the transient behavior of the mixed-mode stress intensity factors.