Stress Intensity Factors For Problems Research Articles

Efficient Computation of Dynamic Stress Intensity Factors for Problems with Stationary Cracks Subjected to Time Dependent Loading

Efficient Computation of Dynamic Stress Intensity Factors for Problems with Stationary Cracks Subjected to Time Dependent Loading

Variation of stress intensity factors for several interface crack problems under arbitrary material combinations

In this paper the variation of interface stress intensity factors is considered under arbitrary material combinations for several problems such as central internal interface cracks, periodic interface cracks, and edge interface cracks. The stress intensity factors for all these problems have been determined in terms of Dundurs’ parameters α, β by the application of FEM in the authors’ previous papers. In this paper, the variations of the stress intensity factors for all these problems are discussed under arbitrary α, β, then the maximum and minimum values of dimensionless stress intensity factors FI,max, FII,max, FI,min, FII,max are indicated on the map of α, β. As an example, it is found that FI,max always appears when (α, β)= (0.2,0.3), and FI,min always appears when (α, β)= (1,0), for the central internal interface cracks independent of crack length.

Stress intensity factor analysis of interface cracks using X‐FEM

AbstractThe extended finite element method (X‐FEM) proposed by Belytschko et al. (International Journal for Numerical Methods in Engineering 1999; 45: 602; 1999; 46: 131; 2001; 50: 993) uses interpolation functions based on the concept of partition of unity, and considers the asymptotic solution and the discontinuity of displacement fields near a crack independently of the finite element mesh. This paper describes the application of X‐FEM to stress analyses of structures containing interface cracks between dissimilar materials. In X‐FEM, an interface crack can be modelled by locally changing an interpolation function in the element near a crack. The energy release rate should be separated into individual stress intensity factors, K1 and K2, because the stress field around the interface crack has mixed modes coupled with mode‐I and mode‐II. For this purpose, various evaluation methods used in conjunction with numerical methods such as FEM and BEM are reviewed. These methods are examined in numerical examples of elastostatic analyses of structures containing interface cracks using X‐FEM. The numerical results show that X‐FEM is an effective method for performing stress analyses and evaluating stress intensity factors in problems related to bi‐material fractures. Copyright © 2003 John Wiley & Sons, Ltd.

Analysis of stress intensity factors in crack problems of periodic two-layered elastic composites

The stress intensity factors in the problem of an interface crack in a periodic two-layered elastic composite subjected to the action of isolated body forces are discussed. The analysis is performed within the framework of the homogenized model with microlocal parameters. The effects of the periodic layered structure of the body on the stress intensity factors are presented.

A finite element analysis of the singular stress fields in anisotropic materials loaded in antiplane shear

AbstractA finite element formulation is developed to determine the order and angular variation of singular stress states at material and geometric discontinuities in anisotropic materials subject to antiplane shear loading. The displacement field of the sectorial element is quadratic in the angular co‐ordinate direction and asymptotic in the radial direction measured from the singular point. The formulation of Yamada and Okumura14 for in‐plane problems is adapted for this purpose. The simplicity and accuracy of the formulation are demonstrated by comparison to several analytical antiplane shear solutions for both isotropic and anisotropic multi‐material wedges and junctions with and without disbonds. The nature and speed of convergence of the eigensolution suggests that the solution presented here could be used in developing enriched elements for accurate and computationally efficient evaluation of stress intensity factors in problems having complex global geometries.

Stress intensity factors for cracks emanating from a curvilinear hole in an anisotropic plane under arbitrary loadings

Based on a specific fundamental solution, which is due to a point force or a concentrated moment acting in an infinite anisotropic plane with a crack, stress intensity factors for problems of a single or two collinear edge cracks emanating from a curvilinear hole can be obtained by satisfying the traction boundary condition on the hole. The fundamental solution used in this study considers inherently the crack geometry and the resultant boundary solutions apply only to the smooth hole. Thus the difficulty in numerical simulation arisen from crack tip singularity can be circumvented. Numerical examples evaluating stress intensity factors for the cracks originating from a circular or an elliptical hole subjected to various loadings are illustrated. The results are in excellent agreement with known solutions. Depending on geometry and the type of loading, the analysis shows that the effect of anisotropy on stress intensity factors may be strong or insignificant. Even under the uniaxial tension or uniform shear loading condition, mixed-mode deformation can still be observed due to the in-plane normal-shear coupling in anisotropy.