Three dimensional fracture analysis of FGM coatings under thermomechanical loading

Yildirim, B
Dağ, Serkan
Erdogan, E
The main objective of this study is to examine the three dimensional surface crack problems in functionally graded coatings subjected to mode I mechanical or transient thermal loading. The surface cracks are assumed to have a semi-elliptical crack front profile of arbitrary aspect ratio. The cracks are embedded in the functionally graded material (FGM) coating which is perfectly bonded to a homogeneous substrate. A three dimensional finite element method is used to solve the thermal and structural problems. Collapsed 20-node isoparametric elements are utilized to simulate the strain singularity around the crack front. The stress intensity factors are computed by using the displacement correlation technique. Four different coating types are considered in the analyses which have homogeneous, ceramic-rich (CR), metal-rich (MR) and linear variation (LN) material composition profiles. In the mechanical loading problems, the composite medium is assumed to be subjected to fixed-grip tension or three point bending. In the thermal analysis, a transient residual stress problem is considered. The stress intensity factors calculated for FGM plates are in good agreement with the previously published results on three dimensional surface cracks. The new results provided show that maximum stress intensity factors computed during transient thermal loading period for the FGM coatings are lower than those of the homogeneous ceramic ones.


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In this study the elastostatic axisymmetric problem for a long thick-walled transversely anisotropic cylinder containing a ring-shaped internal crack is analyzed. The problem is reduced to a singular integral equation which has a simple Cauchy kernel as the dominant part by using Hankel and Fourier transform techniques. These equations are then solved numerically and the stress intensity factors are calculated.
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The main objective of this study is to examine the three-dimensional surface crack problems in orthotropic materials subjected to mechanical or thermal loading. The cracks are modeled and embedded in the orthotropic material by considering semielliptical crack front geometry. In the model special elements are embedded in the crack front region, in this way it is possible to include crack tip singular fields along the crack front. Three-dimensional finite element analyses are conducted to obtain mode I stres...
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A variational formulation of quasi-static brittle fracture in elastic solids at small strains is proposed and an associated finite element implementation is presented. On the theoretical side, a consistent thermodynamic framework for brittle crack propagation is outlined. It is shown that both the elastic equilibrium response as well as the local crack evolution follow in a natural format by exploitation of a global Clausius-Planck inequality. Here, the canonical direction of the crack propagation associate...
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Inan, O; Dağ, Serkan; Erdogan, F (2005-01-01)
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Citation Formats
B. Yildirim, S. Dağ, and E. Erdogan, “Three dimensional fracture analysis of FGM coatings under thermomechanical loading,” INTERNATIONAL JOURNAL OF FRACTURE, pp. 369–395, 2005, Accessed: 00, 2020. [Online]. Available: