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Evaluation of stress intensity factor of multiple inclined cracks under biaxial loading
Frattura ed Integrità Strutturale
A finite rectangular plate of unit thickness with two inclined cracks (parallel and non parallel) under biaxial mixed mode condition are modelled using finite element method. The finite element method is used for determination of stress intensity factors by ANYSIS software. Effects of crack inclination angle on stress intensity factors for two parallel and non parallel cracks are investigated. The significant effects of different crack inclination parameters on stress intensity factors are seen for lower and upper crack in two inclined crack. The present method is validated by comparing the results from available experimental data obtained by photo elastic method in same condition.
Numerical analysis of mixed mode I/II stress intensity factors of edge slant cracked plates
Mixed mode I/II stress intensity factors of an edge slant-cracked plate under tensile loading were assessed. A two-dimensional finite element analysis was employed using ABAQUS. Various crack lengths and angles were analyzed. The effect of the crack location at the plate edge was also examined. Crack initiation angles were calculated. In general, modes I and II stress intensity factor increase with increasing crack length. However, the rate of increase in mode I SIF decreases with increasing the main crack angle. The results showed that stress intensity factors decreased ad the crack mouth approaches the edge mid line. The crack location becomes more significant as the crack length increases. The angle of first cracking depends on crack length, location, and angle.
The stress intensity factor is a traditional topic in mechanics and there have been many solutions for many different cases. The closed frictional crack problem has been modeled in the rock mechanics field where fractures are mostly under compression. Further, the effect of finite plate dimensions under biaxial loading has not been considered in the literature. The key contribution of the present paper is to evaluate the effect of the crack length to plate width ratio on the mode I and II stress intensity factors (SIF) of a central slant crack with frictional surfaces in plates with biaxial loading of different patterns, i.e. tension-tension, tension-compression, compression-tension or compression-compression. A plane strain elastic two-dimensional finite element analysis was adopted. Crack length to plate width ratios equal to 0.1, 0.3 and 0.5 with biaxial ratios from −1 to 1, crack angles from 0 • to 90 • and friction coefficients from 0 to 1 were considered. Contact regimes and the effect of the crack length to plate width ratio were found dependent on biaxial ratio and pattern, friction coefficient and crack angle.
Stress Intensity Factors For Plates With Collinear And Non-Aligned Straight Cracks
2012
Multi-site damage (MSD) has been a challenge to aircraft, civil and power plant structures. In real life components are subjected to cracking at many vulnerable locations such as the bolt holes. However, we do not consider for the presence of multiple cracks. Unlike components with a single crack, these components are difficult to predict. When two cracks approach one another, their stress fields influence each other and produce enhancing or shielding effect depending on the position of the cracks. In the present study, numerical studies on fracture analysis have been conducted by using the developed code based on the modified virtual crack closure integral (MVCCI) technique and finite element analysis (FEA) software ABAQUS for computing SIF of plates with multiple cracks. Various parametric studies have been carried out and the results have been compared with literature where ever available and also with the solution, obtained by using ABAQUS. By conducting extensive numerical stud...
Determination of stress intensity factors for kinked cracks under biaxial loading
The aim of this work is to investigate and determine the stress intensity factors of a finite plate containing kinked cracks under biaxial tension loading. The strain state conditions have been considered for this numerical study using finite element methods. In order to validate the numerical calculations, a straight edged crack with a single kink branch at an angle ∅ from the main crack was studied and normalized mode I and II stress intensity factors results were obtained and compared with other authors. Afterwards, we considered the case of a straight edged crack with two kink branches, with this time having the existence of two symmetrical crack concentration points. The modelization and discretization has been more complex due to the presence of two nearby singularities nevertheless we were able to determine the normalized stress intensity factors for each crack point in mode I and mode II with relative to the variation of kink length ratio, total crack length to width of the plate ratio and bifurcation angles.
International Journal of Pressure Vessels and Piping, 2011
Normalized mixed-mode stress intensity factor equations are presented for deflected and inclined circular surface and corner cracks in finite-thickness plates under uniform remote tensile loading. The equations are obtained by performing non-linear regression analyses on the data from previous numerical solutions based on three-dimensional enriched finite elements. In the equations, the effects of deflection/inclination angles and plate thickness on mixed-mode stress intensity factors are included. The comparisons of normalized stress intensity factors from the equations with those of the finite element analyses show good agreement. Thus, it is concluded that, as a reasonable approximation, the presented equations can be used to assess stress intensity factors and fracture conditions of mixed-mode circular surface and corner cracks in finite-thickness plates.
Engineering Computations, 2009
Purpose-The purpose of this paper is to present special nine-node quadrilateral elements to discretize the un-cracked boundary and the inclined surface crack in a transversely isotropic cuboid under a uniform vertical traction along its top and bottom surfaces by a three-dimensional (3D) boundary element method (BEM) formulation. The mixed-mode stress intensity factors (SIFs), K I , K II and K III , are calculated. Design/methodology/approach-A 3D dual-BEM or single-domain BEM is employed to solve the fracture problems in a linear anisotropic elastic cuboid. The transversely isotropic plane has an arbitrary orientation, and the crack surface is along an inclined plane. The mixed 3D SIFs are evaluated by using the asymptotical relation between the SIFs and the relative crack opening displacements. Findings-Numerical results show clearly the influence of the material and crack orientations on the mixed-mode SIFs. For comparison, the mode-I SIF when a horizontal rectangular crack is embedded entirely within the cuboid is calculated also. It is observed that the SIF values along the crack front are larger when the crack is closer to the surface of the cuboid than those when the crack is far away from the surface. Research limitations/implications-The FORTRAN program developed is limited to regular surface cracks which can be discretized by the quadrilateral shape function; it is not very efficient and suitable for irregular crack shapes. Practical implications-The evaluation of the 3D mixed-mode SIFs in the transversely isotropic material may have direct practical applications. The SIFs have been used in engineering design to obtain the safety factor of the elastic structures. Originality/value-This is the first time that the special nine-node quadrilateral shape function has been applied to the boundary containing the crack mouth. The numerical method developed can be applied to the SIF calculation in a finite transversely isotropic cuboid within an inclined surface crack. The computational approach and the results of SIFs are of great value for the modeling and design of anisotropic elastic structures.
Variation of mixed modes stress intensity factors of an inclined semi-elliptical surface crack
International Journal of Fracture, 1999
In this paper, a singular integral equation method is applied to calculate the stress intensity factor along crack front of a 3D inclined semi-elliptical surface crack in a semi-infinite body under tension. The stress field induced by displacement discontinuities in a semi-infinite body is used as the fundamental solution. Then, the problem is formulated as a system of integral equations
The Effect of the Size and Position of the Crack on the Normalized Stress Intensity Factor
Algerian Journal of Renewable Energy and Sustainable Development
In this work, finite element method was used to determine the normalized stress intensity factors for different configurations. For this, a 2-D numerical analysis with elastic behavior was undertaken in pure I mode. This simulation was carried out using a numerical calculation code. On the basis of the numerical results obtained from the different models treated, there is a good correlation between the nodal displacement extrapolation method (DEM) and the energy method based on the Rice integral (J) to evaluate the normalized stress intensity factors and this for different crack lengths. For each configuration, the increase in the crack size causes an amplification of normalized intensity stresses fators.