Mixed-mode fracture analysis of orthotropic functionally graded material coatings using analytical and computational methods

2008-09-01
This article presents analytical and computational methods for mixed-mode fracture analysis of an orthotropic functionally graded material (FGM) coating-bond coat-substrate structure. The analytical solution is developed by considering an embedded crack in the orthotropic FGM coating. The embedded crack is assumed to be loaded through arbitrary self-equilibrating mixed-mode tractions that are applied to its surfaces. Governing partial differential equations for each of the layers in the trilayer structure are derived in terms of the effective parameters of plane orthotropic elasticity. The problem is then reduced to a system of two singular integral equations, which is solved numerically to evaluate the mixed-mode crack tip parameters. The computational approach is based on the finite element method and is developed by applying the displacement correlation technique. The use of two separate methods in the analyses allowed direct comparisons of the results obtained for an embedded crack in the orthotropic FGM coating, leading to a highly accurate numerical predictive capability. The finite element based approach is used to generate further numerical results by considering periodic cracking in the orthotropic FGM coating. Parametric analyses presented in this article illustrate the influences of the material nonhomogeneity and orthotropy constants, the bond coat thickness, and the crack periodicity on the mixed-mode stress intensity factors and the energy release rate.
JOURNAL OF APPLIED MECHANICS-TRANSACTIONS OF THE ASME

Suggestions

Delamination of compressively stressed orthotopic functionally graded material coatings under thermal loading
YILDIRIM, BORA; Yilmaz, Suphi; Kadıoğlu, Fevzi Suat (ASME International, 2008-09-01)
The objective of this study is to investigate a particular type of crack problem in a layered structure consisting of a substrate, a bond coat, and an orthotropic functionally graded material coating. There is an internal crack in the orthotropic coating layer. It is parallel to the coating bond-coat interface and perpendicular to the material gradation of the coating. The position of the crack inside the coating is kept as a variable. Hence, the case of interface crack is also addressed. The top and bottom...
Multi-scale characterization of particle clustering in discontinuously reinforced composites
CETIN, Arda; Kalkanlı, Ali (Elsevier BV, 2009-06-01)
The applicability of a quantitative characterization scheme for cluster detection in particle reinforced composites is discussed. The method considers the pattern from the perspective of individual particles, so that even in a pattern that globally conforms to a random distribution, micro-scale heterogeneities can be detected. The detected clusters are visualized by kernel surfaces. Results indicate that the presented methodology is an effective discriminator of clusters and can successfully be used for qua...
Coupled thermoviscoplasticity of glassy polymers in the logarithmic strain space based on the free volume theory
Miehe, Christian; Mendez Diez, Joel; Göktepe, Serdar; Schaenzel, Lisa Marie (Elsevier BV, 2011-06-15)
The paper outlines a constitutive model for finite thermo-visco-plastic behavior of amorphous glassy polymers and considers details of its numerical implementation. In contrast to existing kinematical approaches to finite plasticity of glassy polymers, the formulation applies a plastic metric theory based on an additive split of Lagrangian Hencky-type strains into elastic and plastic parts. The analogy between the proposed formulation in the logarithmic strain space and the geometrically linear theory of pl...
Analysis of material instabilities in inelastic solids by incremental energy minimization and relaxation methods: evolving deformation microstructures in finite plasticity
MIEHE, CHRISTIAN; LAMBRECHT, MATTHIAS; Gürses, Ercan (Elsevier BV, 2004-12-01)
We propose an approach to the definition and analysis of material instabilities in rate-independent standard dissipative solids at finite strains based on finite-step-sized incremental energy minimization principles. The point of departure is a recently developed constitutive minimization principle for standard dissipative materials that optimizes a generalized incremental work function with respect to the internal variables. In an incremental setting at finite time steps this variational problem defines a ...
Mixed-mode fracture analysis of orthotropic functionally graded materials under mechanical and thermal loads
Dağ, Serkan; Sarikaya, Duygu (Elsevier BV, 2007-12-01)
Mixed-mode fracture problems of orthotropic functionally graded materials (FGMs) are examined under mechanical and thermal loading conditions. In the case of mechanical loading, an embedded crack in an orthotropic FGM layer is considered. The crack is assumed to be loaded by arbitrary normal and shear tractions that are applied to its surfaces. An analytical solution based on the singular integral equations and a numerical approach based on the enriched finite elements are developed to evaluate the mixed-mo...
Citation Formats
S. Dağ, “Mixed-mode fracture analysis of orthotropic functionally graded material coatings using analytical and computational methods,” JOURNAL OF APPLIED MECHANICS-TRANSACTIONS OF THE ASME, pp. 0–0, 2008, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/35788.