Three-Dimensional Analysis of Mixed Mode Compact-Tension-Shear (CTS) Specimens: Stress Intensity Factors, T-stresses and Crack Initiation Angles

A failure criterion is proposed for ductile fracture in U-notched components under mixed mode static loading. The Compact Tension Shear (CTS) is the preferred test specimen used to determine stress intensity factor in the mode I, mode II and the mixed-mode fracture. In this work, the mode I and mode II stress intensity factors were computed for different notch ratio lengths 0.1<a/W<0.7, of the inner radius of notch 0.25mm<ρ<4mm and load orientation angles 0°<α< 90° using finite element analysis. However, a review of numerical analysis results reveals that the conventional fracture criteria with only stress intensity factors (NSIFs) Kρ first term of Williams’s solution provide different description of stress field around notch zone comparing with results introduce the second and third parameter T-stress and A3.

Download Full-text

Three Dimensional Modeling of Inclined Surface Cracks in FGM Coatings

Materials Science Forum ◽

10.4028/www.scientific.net/msf.631-632.109 ◽

2009 ◽

Vol 631-632 ◽

pp. 109-114

Author(s):

Sadik Kosker ◽

Serkan Dag ◽

Boray Yildirim

Keyword(s):

Stress Intensity ◽

Stress Intensity Factors ◽

Mixed Mode ◽

Thermal Stresses ◽

Three Dimensional ◽

Transient Behavior ◽

Correlation Technique ◽

Mixed Mode Fracture ◽

Intensity Factors ◽

Parametric Analyses

This study presents a three dimensional finite element method for mixed-mode fracture analysis of an FGM coating-bond coat-substrate structure. The FGM coating is assumed to contain an inclined semi-elliptical crack at the free surface. The trilayer structure is examined under the effect of transient thermal stresses. Strain singularity around the crack front is simulated by utilizing collapsed wedge-shaped singular elements. The modes I, II and III stress intensity factors are computed by applying the displacement correlation technique and presented as a function of time. Four different FGM coating types are examined in the parametric analyses which are metal-rich, ceramic-rich, linear variation and homogeneous coatings. The results provided illustrate the influences of the FGM coating type and crack inclination angle on the transient behavior of the mixed-mode stress intensity factors.

Download Full-text

A General Numerical Procedure for Extracting Mixed-Mode Stress Intensity Factors Along the Fronts of Three-Dimensional Nonplanar Cracks

Recent Advances in Solids and Structures ◽

10.1115/imece2002-32289 ◽

2002 ◽

Author(s):

M. Gosz ◽

R. Cammino

Keyword(s):

Stress Intensity ◽

Stress Intensity Factors ◽

Mixed Mode ◽

Three Dimensional ◽

Numerical Procedure ◽

Intensity Factors ◽

Hydrostatic Tension ◽

Energy Integrals ◽

Shaped Crack ◽

Mode Stress

A numerical procedure is described for extracting mixed-mode stress intensity factors along the fronts of three-dimensional, nonplanar cracks embedded in solids. The mixed-mode stress intensity factors at points along the crack front are obtained by evaluating interaction energy integrals for three-dimensional, non-planar cracks. To assess the validity of the numerical procedure, two numerical examples are considered. First, we consider the problem of a non-planar, lens-shaped crack in an infinite solid subjected to hydrostatic tension. The numerical results are shown to be in excellent agreement with available analytical results. We then consider the case of a non-planar, warped elliptical crack surface, where to our knowledge no analytical solution exists, and the results are discussed.

Download Full-text