scholarly journals Investigation on the Effect of Crack Length on Mechanical Properties of Functionally Graded Materials

2010 ◽  
Vol 44-47 ◽  
pp. 2244-2248
Author(s):  
Gang Chen ◽  
Xi Yu Zhao ◽  
Peng Cheng Zhai
Keyword(s):  
Mechanical Properties ◽  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Crack Length ◽  
Pure Metal ◽  
Functionally Graded ◽  
Crack Tip Field ◽  
Graded Materials ◽  
Barrier Coating

In this article, the thermo-mechanical responses of ceramic/metal functionally graded thermal barrier coating(TBC) in work environment are analyzed by a finite element method. Both the crack-tip field and the stress intensity factor of functionally graded TBC are analyzed and calculated. It is discussed that the effect of crack length on mechanical properties of functionally graded TBC in the condition creep and no creep of pure metal. The numerical results indicate that the effect of crack length(a/t) is negligible to temperature distributions and the maximum displacements of whole model but remarkable to the 1st principal stress and stress intensity factor of crack region. Moreover, creep phenomenon of pure metal can relax the value of displacement, stress and stress intensity factor but do not alter their distribution.

Collinear Crack Problem in Antiplane Elasticity for a Strip of Functionally Graded Materials

2004 ◽  
Vol 20 (3) ◽  
pp. 167-175 ◽  
Author(s):  
Y. Z. Chen
Keyword(s):  
Stress Intensity Factor ◽  
Integral Equation ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Crack Problem ◽  
Functionally Graded ◽  
Elementary Solution ◽  
Collinear Crack ◽  
Graded Materials ◽  
Antiplane Elasticity

AbstractIn this paper, elastic analysis for a collinear crack problem in antiplane elasticity of functionally graded materials (FGMs) is present. An elementary solution is obtained, which represents the traction applied at a point “x” on the real axis caused by a point dislocation placed at a point “t” on the same real axis. The Fourier transform method is used to derive the elementary solution. After using the obtained elementary solution, the singular integral equation is formulated for the collinear crack problem. Furthermore, from the solution of the singular integral equation the stress intensity factor at the crack tip can be evaluated immediately. In the solution of stress intensity factor, influence caused by the materials property “α” is addressed. Finally, numerical solutions are presented.

Dynamic Analysis of Antiplane Crack under SH-Waves in the Functionally Graded Materials

2007 ◽  
Vol 353-358 ◽  
pp. 38-41
Author(s):  
Xin Gang Li ◽  
Cheng Jin ◽  
Li Zhang ◽  
Da Yong Chu
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Functionally Graded Materials ◽  
Dynamic Stress ◽  
Dynamic Stress Intensity Factor ◽  
Infinite Plate ◽  
Functionally Graded ◽  
Graded Materials ◽  
Sh Waves

In this paper, the behavior of a finite crack in an infinite plate of functionally graded materials (FGM) with free boundary subjected to SH-waves is considered. To make the analysis tractable, it is assumed that the material properties vary exponentially with the thickness direction and the problem is transformed into a dual integrated equation with the method of integral transform. The dynamic stress intensity factor is obtained using Schmidt method. The numerical examples are presented to demonstrate this numerical technique for SH-waves propagating in FGM plate. Finally the number of the waves, the gradient parameter of FGM and the angle of the incidence upon the dynamic stress intensity factor are also given.

The Moving Crack Problem of Orthotropic Functionally Graded Materials under Antiplane Loading

2008 ◽  
Vol 33-37 ◽  
pp. 687-692
Author(s):  
Jun Lin Li ◽  
Zhong He Sui ◽  
Wei Yang Yang
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Functionally Graded Materials ◽  
Dynamic Stress ◽  
Dynamic Stress Intensity Factor ◽  
Functionally Graded ◽  
Infinite Strip ◽  
Graded Materials ◽  
Moving Speed

Dynamic problems of Yoffe mode crack are studied under antiplane shear impact in infinite orthotropic functionally graded materials. The shear modules in two directions are assumed to vary in terms with power function form of dual parameters of arbitrary time power. By using integral transform-dual integral equations method, the stress field and dynamic stress intensity factor near crack tip are obtained. And the influences of material in homogenous coefficient and graded parameters and crack moving speed to dynamic stress intensity factor are analyzed in virtue of Matlab software. Results show that the dimensionless dynamic stress intensity factor will decrease with the increase of moving speed of crack, which is opposite to the result of the dynamic problem of infinite strip in FGM. And the dimensionless dynamic stress intensity factor will decrease with the increase of graded parameters and rise with the increase of material in homogenous coefficient.

Fracture Dynamics of a Mode III Moving Crack Impacted by Elastic Wave in Functionally Graded Materials

2010 ◽  
Vol 105-106 ◽  
pp. 683-686
Author(s):  
Xin Gang Li ◽  
Zhen Qing Wang ◽  
Nian Chun Lü
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Functionally Graded Materials ◽  
Dynamic Stress ◽  
Dynamic Stress Intensity Factor ◽  
Functionally Graded ◽  
Moving Crack ◽  
Graded Materials ◽  
Sh Waves

The dynamic stress field under the SH-waves at the moving crack tip of functionally graded materials is analyzed, and the influences of parameters such as graded parameter, crack velocity, the angle of the incidence and the number of the waves on dynamic stress intensity factor are also studied. Due to the same time factor of scattering wave and incident wave, the scattering model of the crack tip can be constructed by making use of the displacement function of harmonic load in the infinite plane. The dual integral equation of moving crack problem subjected to SH-waves is obtained through Fourier transform with the help of the exponent model of the shear modulus and density, then have some process on the even and odd term of the integral kernel. The displacement is expanded into series form using Jacobi Polynomial, and then the semi-analytic and numerical solutions of dynamic stress intensity factor are derived with Schmidt method.

General Method for Optimizing Composite Patch Repairs

2015 ◽  
Vol 1120-1121 ◽  
pp. 670-674
Author(s):  
Abdelmadjid Ait Yala ◽  
Abderrahmanne Akkouche
Keyword(s):  
Mechanical Properties ◽  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Optimization Problem ◽  
Composite Patch ◽  
Matlab Program ◽  
Patch Repairs ◽  
Selection Of ◽  
General Method

The aim of this work is to define a general method for the optimization of composite patch repairing. Fracture mechanics theory shows that the stress intensity factor tends towards an asymptotic limit K∞.This limit is given by Rose’s formula and is a function of the thicknesses and mechanical properties of the cracked plate, the composite patch and the adhesive. The proposed approach consists in considering this limit as an objective function that needs to be minimized. In deed lowering this asymptote will reduce the values of the stress intensity factor hence optimize the repair. However to be effective this robust design must satisfy the stiffness ratio criteria. The resolution of this double objective optimization problem with Matlab program allowed us determine the appropriate geometric and mechanical properties that allow the optimum design; that is the selection of the adhesive, the patch and their respective thicknesses.

Effect of specimen crack lengths on stress intensity factor for Al6061-TiC composites using experimental and 3D numerical methods

2017 ◽  
Vol 8 (5) ◽  
pp. 506-515 ◽  
Author(s):  
Raviraj M.S. ◽  
Sharanaprabhu C.M. ◽  
Mohankumar G.C.
Keyword(s):  
Stress Intensity Factor ◽  
Finite Element ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Crack Length ◽  
Finite Element Simulations ◽  
Experimental Results ◽  
Crack Mouth Opening Displacement ◽  
3D Finite Element ◽  
Content Type

Purpose The purpose of this paper is to present the determination of critical stress intensity factor (KC) both by experimental method and three-dimensional (3D) finite element simulations. Design/methodology/approach CT specimens of different compositions of Al6061-TiC composites (3wt%, 5wt% and 7wt% TiC) with variable crack length to width (a/W=0.3-0.6) ratios are machined from as-cast composite block. After fatigue pre-cracking the specimens to a required crack length, experimental load vs crack mouth opening displacement data are plotted to calculate the KC value. Elastic 3D finite element simulations have been conducted for CT specimens of various compositions and a/W ratios to compute KC. The experimental results indicate that the magnitude of KC depends on a/W ratios, and significantly decreases with increase in a/W ratios of the specimen. Findings From 3D finite element simulation, the KC results at the centre of CT specimens for various Al6061-TiC composites and a/W ratios show satisfactory agreement with experimental results compared to the surface. Originality/value The research work contained in this manuscript was conducted during 2015-2016. It is original work except where due reference is made. The authors confirm that the research in their work is original, and that all the data given in the article are real and authentic. If necessary, the paper can be recalled, and errors corrected.

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