Dynamic frictional contact problems involving functionally graded materials

Download

index.pdf

Date

2018

Author

Balcı, Mehmet Nurullah

Metadata

Show full item record

Item Usage Stats

276
views

159
downloads

The main aim of this study is to analyze the dynamic frictional contact problem of layered and functionally graded materials. Investigating contact problems including dynamic effects has a significant importance in mechanical engineering applications since many contact problems arise between moving structures. In moving contact problems, speed of the punch may not be so small to ignore dynamic effects. Hence, contact problem should be examined using elastodynamics theory. In this study, both frictional moving contact problems of homogenous elastic coatings and functionally graded coatings pressed by a moving rigid punch with various punch profiles are considered. The rigid punch is pressed against the coating and it moves at a constant subsonic speed. Governing partial differential equations are solved analytically using Galilean and Fourier transformation techniques. Displacement fields in both coating and the substrate are found by applying boundary and interface continuity conditions. Equations for the mixed boundary value problem is reduced to a singular integral equation of the second kind including unknown normal contact stress. The singular integral equation is solved numerically using a suitable expansion-collocation technique and normal contact stress is found. A verification study for elastostatic contact analysis is carried out using computational results generated by the use of finite element method. A verification study for elastodynamic contact analysis is conducted by utilizing available results in the literature. Consequently, the influences of punch profile, punch sliding speed, material inhomogeneity, coefficient of friction and coating thickness on contact stresses and punch stress intensity factors are investigated.

Subject Keywords

Friction., Mechanical wear., Contact mechanics., Mechanics, Applied., Functionally gradient materials.

URI

http://etd.lib.metu.edu.tr/upload/12622825/index.pdf
https://hdl.handle.net/11511/27810

Collections

Graduate School of Natural and Applied Sciences, Thesis

Suggestions

OpenMETU
Core

Thermal stress intensity factor evaluation for inclined cracks in functionally graded materials using Jk-integral method Demirçivi, Bengi; Dağ, Serkan; Department of Mechanical Engineering (2006) The main objective of this study is to evaluate mixed mode stress intensity factors for inclined embedded cracks in functionally graded materials. Fracture analysis of inclined cracks requires the calculation of both Mode I and Mode II stress intensity factors ( I K , II K ). In this study, k J -integral is used to calculate I K and II K . Equivalent domain integral approach is utilized to evaluate the k J - integral around the crack tip. The present study aims at developing a finite element model to study ...
Thermal stress problem for an FGM strip containing periodic cracks Köse, Ayşe; Kadıoğlu, Fevzi Suat; Department of Mechanical Engineering (2013) In this study the plane linear elastic problem of a functionally graded layer which contains periodic cracks is considered. The main objective of this study is to determine the thermal stress intensity factors for edge cracks. In order to find an analytic solution, Young’s modulus and thermal conductivity are assumed to be varying exponentially across the thickness, whereas Poisson ratio and thermal diffusivity are taken as constant. First, one dimensional transient and steady state conduction problems are ...
Mixed-mode fracture analysis of orthotropic FGM coatings under mechanical and thermal loads İlhan, Küçük Ayşe; Dağ, Serkan; Department of Mechanical Engineering (2007) In this study, it is aimed to investigate the mixed-mode fracture behavior of orthotropic functionally graded material (FGM) coatings bonded to a homogeneous substrate through a homogeneous bond-coat. Analytical and computational methods are used to solve the embedded cracking problems under mechanical or thermal loading conditions. It is assumed that the material property gradation of the FGM coating is in the thickness direction and cracks are parallel to the boundaries. The principal axes of orthotropy a...
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...
Frictional Hertzian contact between a laterally graded elastic medium and a rigid circular stamp Dağ, Serkan; YILDIRIM, BORA; Ozatag, A. Cihan (Springer Science and Business Media LLC, 2013-08-01) This study investigates the problem of sliding frictional contact between a laterally graded elastic medium and a rigid circular stamp. Analytical and computational methods are developed to evaluate the contact stresses. In the analytical formulation, spatial variation in the shear modulus of the graded medium is represented by an exponential function, and Poisson's ratio is taken as a constant. Coulomb's dry friction law is assumed to hold within the contact area. The two-dimensional plane elasticity probl...

Citation Formats

M. N. Balcı, “Dynamic frictional contact problems involving functionally graded materials,” Ph.D. - Doctoral Program, Middle East Technical University, 2018.