Thermal fracture analysis of orthotropic functionally graded materials using an equivalent domain integral approach

A new computational method based on the equivalent domain integral (EDI) is developed for mode I fracture analysis of orthotropic functionally graded materials (FGMs) subjected to thermal stresses. By using the constitutive relations of plane orthotropic thermoelasticity, generalized definition of the J-integral is converted to an equivalent domain integral to calculate the thermal stress intensity factor. In the formulation of the EDI approach, all the required thermomechanical properties are assumed to have continuous spatial variations through the functionally graded medium. Developed methodology is integrated into a fracture mechanics research finite element code FRAC2D using graded finite elements that possess cubic interpolation. Steady-state and transient temperature distribution profiles in orthotropic FGMs are computed using the finite elements based heat transfer analysis software HEAT2D. EDI method is validated and domain independence is demonstrated by comparing the numerical results obtained using EDI to those calculated by an enriched finite element method and to those available in the literature. Single and periodic edge crack problems in orthotropic FGMs are examined in order to study the influences of principal thermal expansion coefficient and thermal conductivity components, relative crack length and crack periodicity on the thermal stress intensity factors. Numerical results show that among the three principal thermal expansion coefficient components, the in-plane component perpendicular to the crack axis has the most significant influence on the mode I stress intensity factor. Gradation profile of the thermal expansion coefficient parallel to the crack axis is shown to have no effect on the outcome of the fracture analysis.


Computational Methods for Inclined Cracks in Orthotropic Functionally Graded Materials Under Thermal Stresses
Dağ, Serkan; TOPAL, SERRA (2013-10-03)
This article sets forth two different computational methods developed to evaluate fracture parameters for inclined cracks lying in orthotropic functionally graded materials, that are under the effect of thermal stresses. The first method is based on the J(k)-integral, whereas the second entails the use of the J(1)-integral and the asymptotic displacement fields. The procedures introduced are implemented by means of the finite element method and integrated into a general purpose finite element analysis softw...
Contact mechanics of graded materials: Analyses using singular integral equations
Dağ, Serkan (2006-10-18)
Contact stress distribution at an FGM surface is evaluated using an analytical technique based on the singular integral equations. An FGM half-plane is assumed to be in sliding contact with a rigid stamp of an arbitrary profile. The functionally graded medium is assumed to possess two-dimensional material property variations. Two independent nonhomogeneity constants are used to derive the governing partial differential equations. By using the integral transform techniques, all boundary conditions are satisf...
Sliding frictional contact between a rigid punch and a laterally graded elastic medium
Dağ, Serkan; Yidirim, Bora; Ozatag, A. Cihan (2009-11-01)
Analytical and computational methods are developed for contact mechanics analysis of functionally graded materials (FGMs) that possess elastic gradation in the lateral direction. In the analytical formulation, the problem of a laterally graded half-plane in sliding frictional contact with a rigid punch of an arbitrary profile is considered. The governing partial differential equations and the boundary conditions of the problem are satisfied through the use of Fourier transformation. The problem is then redu...
Hybrid finite element for analysis of functionally graded beams
Sarıtaş, Afşin; Soydas, Ozan (2017-01-01)
A hybrid finite element model is presented, where stiffness and mass distributions over a beam with functionally graded material (FGM) are accurately modeled for both elastic and inelastic material responses. Von Mises and Drucker-Prager plasticity models are implemented for metallic and ceramic parts of FGM, respectively. Three-dimensional stress-strain relations are solved by a general closest point projection algorithm, and then condensed to the dimensions of the beam element. Numerical examples and veri...
Failure analysis of tapered composite structures under tensile loading
Çelik, Ozan; Parnas, Kemal Levend; Department of Mechanical Engineering (2016)
A three dimensional finite element modeling approach is used to evaluate the effects of preliminary design variables on the performance of tapered composite laminates under tensile loading. Hashin failure criteria combined with a progressive failure algorithm is used for in-plane failure mechanisms and cohesive zone method is used for out-of-plane failures. The modeling approach is validated by a comparison with experimental results from literature. The validated model is used to examine various design vari...
Citation Formats
S. Dağ, “Thermal fracture analysis of orthotropic functionally graded materials using an equivalent domain integral approach,” ENGINEERING FRACTURE MECHANICS, pp. 2802–2828, 2006, Accessed: 00, 2020. [Online]. Available: