Error estimation of numerical stress intensity factors for semi-elliptical cracks

In this study, mode I stress intensity factors for a three-dimensional finite cracked body with arbitrary shape and subjected to arbitrary loading is presented by using the boundary weight function method. The weight function is a universal function for a given cracked body and can be obtained from any arbitrary loading system. A numerical finite element method for the determination of weight function relevant to cracked bodies with finite dimensions is used. Explicit boundary weight functions are successfully demonstrated by using the least-squares fitting procedure for elliptical quarter-corner crack and embedded elliptical crack in parallelepipedic finite bodies. If the stress distribution of a cut-out parallelepipedic cracked body from any arbitrary shape of cracked body subjected to arbitrary loading is determined, the mode I stress intensity factors for the cracked body can be obtained from the predetermined boundary weight functions by a simple surface integration. Comparison of the calculated results with some available solutions in the published literature confirms the efficiency and accuracy of the proposed boundary weight function method.

Stress intensity factors for axial semi-elliptical surface cracks and embedded elliptical cracks at longitudinal butt welded joints of steel-lined pressure tunnels and shafts considering weld shape

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

Three-Dimensional Mixed Mode Stress Intensity Factors for Inclined Elliptical Surface Cracks in Plates under Uniform Tensile Load

Determination of the Stress Intensity Factor of an elliptical breathing crack in a rotating shaft

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

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

Formulae of stress intensity factors at tips of kinked cracks under various loadings

A method is developed to evaluate the stress intensity factors (SIFs) for semi-elliptical circumferential cracks located at the inner wall of a pipe under arbitrary welding residual stress distribution. To accomplish this, at first, the three-dimensional finite element analysis (FEA) is performed employing singular elements along the crack front. Next, the weight function (WF) is incorporated in conjunction with the finite element results to predict the SIFs of semi-elliptical circumferential cracks in pipes. Then, the presented WF is extended to estimate the SIFs of fully circumferential cracks in pipes. Moreover, a closed-form formulation of SIFs is presented as a function of arbitrary loading condition and crack geometry. Finally, the closed-form relation has been used to predict the stress intensity factors of circumferential cracks under highly nonlinear residual stress fields. Comparison of the results and those in the literature shows an acceptable agreement.

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

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.

Stress intensity factors for surface cracks at countersunk holes

Approximate Green's functions for singular and higher order terms of an edge crack in a finite plate

Methods of calculating stress intensity factors for nozzle corner cracks

Stress intensity factors and weight functions for high aspect ratio semi-elliptical surface cracks in finite-thickness plates