Stress Intensity Factor for Interface Cracks in Bimaterials Using Complex Variable Meshless Manifold Method

On the calculation of stress intensity factors for surface cracks in welded pipe–plate and tubular joints

Boundary element analysis of thermal stress intensity factors for interface griffith and cusp cracks

Stress intensity factors for cracks in grooved rolls used for hot-rolling

Computation of stress intensity factors for interfacial cracks

Calculation of stress intensity factors for interlaminar cracks in composite laminates

Weight function method for three dimensional crack problems—II. Application to surface cracks at a hole in finite thickness plates under stress gradients

Although a lot of interface crack problems were previously treated, few solutions are available under arbitrary material combinations. This paper deals with an edge interface crack in bonded finite and semi-infinite plates under tension. Then, the effects of material combination on the stress intensity factors are discussed. A useful method to calculate the stress intensity factor of interface crack is presented with focusing on the stresses at the crack tip calculated by the finite element method. The stress intensity factors are indicated in charts under arbitrary material combinations. For small edge interface crack, it is found that the dimensionless stress intensity factors FI and FII are not always finite depending on Dundurs' parameters α and β. In the present study, the variations of the dimensionless stress intensity factors FI and FII are clarified under arbitrary material combination with varying the relative crack length a/W. It is found that when a/W ≤ 0.4 the value of FI increases with increasing α and when a/W ≥ 0.4 the value of FI decreases with increasing α.

In-plane stress analysis of dissimilar materials with multiple interface cracks

An extended finite element method (X-FEM) for three-dimensional crack modelling is described. A discontinuous function and the two-dimensional asymptotic crack-tip displacement fields are added to the finite element approximation to account for the crack using the notion of partition of unity. This enables the domain to be modelled by finite elements with no explicit meshing of the crack surfaces. Computational geometry issues associated with the representation of the crack and the enrichment of the finite element approximation are discussed. Stress intensity factors (SIFs) for planar three-dimensional cracks are presented, which are found to be in good agreement with benchmark solutions. Copyright © 2000 John Wiley & Sons, Ltd.

The interface crack problem for a piezoelectric bimaterial based on permeable conditions is studied numerically. To find the singular electromechanical field at the crack tip, an asymptotic solution is derived in connection with the conventional finite element method. For mechanical and electrical loads, the complex stress intensity factor for an interface crack is obtained. The influence of the applied loads on the electromechanical fields near the crack tip is also studied. For a particular case of a short crack with respect to the bimaterial size, the numerical results are compared with the exact analytical solutions, obtained for a piezoelectric bimaterial plane with an interface crack.

Methods of calculating stress intensity factors for nozzle corner cracks

A straight-forward method for calculating the stress intensity factors (or the energy release rate and mode mixity) for interfacial cracks in bi-materials has been developed. An existing method for homogeneous materials, based on the computation of the energy release rate from the nodal forces and displacements given by a finite element analysis, was modified to include the mismatch in material properties. Thick thermal barrier coatings usually fail as a result of cracking near the interface. The influence of the thickness and the edge angle of the coating on the energy release rate and mode mixity for a small edge crack at the interface of a TBC system subjected to thermal loading was investigated. It was established that the high energy release rates obtained for thick coatings can be reduced by decreasing the edge angle of the coating. Additionally a comparison with energy release rates given by J-integral computations has been done.

The elastodynamic response of an infinite non-homogeneous orthotropic material with an interfacial finite crack under distributed normal and shear impact loads is examined. Solution for the stress intensity factor history around the crack tips is found. Laplace and Fourier transforms are employed to solve the equations of motion leading to a Fredholm integral equation on the Laplace transform domain. The dynamic stress intensity factor history can be computed by numerical Laplace transform inversion of the solution of the Fredholm equation. Numerical values of the dynamic stress intensity factor history for some materials are obtained. Interfacial cracks between two different materials and between two pieces of the same material but different fiber orientation are considered. Bimaterial formulation of a crack problem is shown to converge to the mono-material formulation, derived independently, in the limiting case when both materials are the same.

A procedure is formulated to derive approximate stress intensity factors for both part-through and through-the-thickness cracks originating at open holes and holes containing either loaded or unloaded close tolerance fasteners. The procedure is checked with known solutions for stress intensity factors of one or two through-the-thickness cracks emanating from an open hole in a plate subjected to uniaxial or biaxial loading. Stress intensity factors computed from this procedure for the above mentioned cases agree within seven percent of known results for the crack length to hole radius ratios, L/r, of 0.05 ≤ L/r < ∞. The procedure is then used to derive stress intensity factors for through cracks at loaded close tolerance fasteners in a plate, and for semi-elliptical cracks at open holes and at loaded and unloaded close tolerance fastener filled holes in a thick plate. Stress intensity factors for these part-through cracks are presented in graphical forms as a function of position around the crack periphery, for various crack aspect ratios and crack length to hole radius ratios. Finally, these stress intensity solutions for semi-elliptical cracks at a fastener hole in a thick plate are used to estimate stress intensity factors for quarter-elliptical cracks originating at a fastener hole in a finite thickness plate.

2D weight functions of stress intensity factors for high aspect ratio semi-elliptical surface cracks in finite thickness plate