Jk-integral formulation and implementation for thermally loaded orthotropic functionally graded materials

Download
index.pdf
2008
Arman, Eyüp Erhan
Show full item record
195
views
51
downloads
The main aim of this study is to utilize a Jk-integral based computational method in order to calculate crack tip parameters for orthotropic functionally graded materials (FGMs). The crack is subjected to mixed mode thermal loading. Mixed mode thermal fracture analysis requires the calculation of mode-I and mode-II stress intensity factors (KI ,KII ). In addition to stress intensity factors, energy release rate and T-stress are calculated by means of Jk-integral. Jk-integral is defined as a line integral over a vanishingly small curve. Since it is difficult to deal with a line integral on a vanishing curve , Jk-integral is converted to a domain independent form containing area and line integrals by the help of plane thermoelasticity constitutive relations. Steady-state temperature distribution profiles in FGMs and the components of the Jk-integral are computed by means of the finite element method. In both thermal and structural analyses, finite element models that possess graded isoparametric elements are created in the general purpose finite element analysis software ANSYS. In the formulation of Jk-integral, all required engineering material properties are assumed to possess continuous spatial variations through the functionally graded medium. The numerical results are compared to the results obtained from Displacement Correlation Technique (DCT). The domain independence of Jk-integral is also demonstrated. The results obtained in this study show the effects of crack location and material property gradation profiles on stress intensity factors, energy release rate and T-stress.
Mechanical engineering.
http://etd.lib.metu.edu.tr/upload/3/12610136/index.pdf
https://hdl.handle.net/11511/18042
Graduate School of Natural and Applied Sciences, Thesis

Suggestions

Fatigue crack growth analysis models for funcionally graded materials
Sabuncuoğlu, Barış; Dağ, Serkan; Department of Mechanical Engineering (2006)
The objective of this study is to develop crack growth analysis methods for functionally graded materials under mode I cyclic loading by using finite element technique. The study starts with the analysis of test specimens which are given in ASTM standard E399. The material properties of specimens are assumed to be changing along the thickness direction according to a presumed variation function used for the modeling of functionally graded materials. The results of the study reveal the influence of different...
Development of test structures and methods for characterization of MEMS materials
Yıldırım, Ender; Arıkan, Mehmet Ali Sahir; Department of Mechanical Engineering (2005)
This study concerns with the testing methods for mechanical characterization at micron scale. The need for the study arises from the fact that the mechanical properties of materials at micron scale differ compared to their bulk counterparts, depending on the microfabrication method involved. Various test structures are designed according to the criteria specified in this thesis, and tested for this purpose in micron scale. Static and fatigue properties of the materials are aimed to be extracted through the ...
Three dimensional fracture analysis of FGM coatings
İnan, Özgür; Dağ, Serkan; Department of Mechanical Engineering (2004)
The main objective of this study is to model the three dimensional surface cracking problem in Functionally Graded Material (FGM) coatings bonded to homogeneous substrates. The FGM coating is assumed to be a (ZrO2) ا (Ti-6Al-4V) layer. Homogeneous ceramic, metal ا rich, ceramic ا rich and linear variation material compositions are considered in the analyses. The surface crack is assumed to have a semi ا circular crack front profile. The surface crack problem in the FGM coating ا substrate system is examined...
Analytical solution of a crack problem in a radially graded FGM
Çetin, Suat; Kadıoğlu, Fevzi Suat; Department of Mechanical Engineering (2007)
The objective of this study is to determine stress intensity factors (SIFs) for a crack in a radially graded FGM layer on a substrate. Functionally graded coating with an edge crack perpendicular to the interface and a homogeneous substrate are bonded together. In order to make the problem analytically tractable, geometry is modeled as an FGM strip attached to a homogeneous layer. Introducing the elastic foundation underneath the homogeneous layer, an FGM coating on a thin walled cylinder can be modeled. At...
Uncertainty analysis of coordinate measuring machine (CMM) measurements
Sözak, Ahmet; Konukseven, Erhan İlhan; Department of Mechanical Engineering (2007)
In this thesis, the measurement uncertainty of Coordinate Measuring Machine (CMM) is analysed and software is designed to simulate this. Analysis begins with the inspection of the measurement process and structure of the CMMs. After that, error sources are defined with respect to their effects on the measurement and then an error model is constructed to compensate these effects. In other words, systematic part of geometric, kinematic and thermal errors are compensated with error modelling. Kinematic and geo...
Citation Formats
E. E. Arman, “Jk-integral formulation and implementation for thermally loaded orthotropic functionally graded materials,” M.S. - Master of Science, Middle East Technical University, 2008.
METU IIS - Integrated Information Service open@metu.edu.tr