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We predict the fatigue propagation of corner cracks from cold worked holes using three dimensional finite element models. The models account for the through thickness variation in residual stress left after cold working. The predictions are compared to experimental results in aluminum 2024-T351 and 7075-T651. The models show the evolution of P-shaped crack fronts similar to those observed in experiments. Predictions based on the initial residual stress field left after cold working were nonconservative, predicting either slower than experimental crack growth or crack growth that arrests. Predictions based on an estimate of the stable relaxed residual stress field near the hole were conservative, and predicted 5–10 times greater life than the current Department of Defense reduced initial flaw size approach.

Asymptotic stress and displacement fields near the tip of a sharp anisotropic bimaterial interface corner are computed using a combination of the Stroh formalism and the Williams eigenfunction expansion method. From the asymptotic fields, the path independent H-integral is developed and implemented to calculate anisotropic interface corner stress intensities. The calculation procedure is demonstrated for two glass–silicon interface corner configurations that commonly arise in practice in the microsensor industry. In each case, the bimaterial interface corner experiences mixed mode I and II loading, and accurate estimates of both stress intensities are obtained.

We present a procedure to calculate mode I and II notch stress intensities in anisotropic media using the path-independent H-integral. The method is based on coupling the analysis of asymptotic stress and displacement fields near a sharp notch with a path independent integral that results from the application of Betti's reciprocal theorem to the notched solid. The approach is demonstrated for two loading/geometry combinations that arise naturally in etched single crystal silicon: mode I loading of a 70.53° notch and mixed mode I and II loading of a T-structure with a 90° notch. Results agree well with those obtained by correlating computed notch-flank displacements with the asymptotic solution.

We present simple, closed-form expressions for stress intensity factors for cracked I-beams subjected to a bending moment. The estimates are based on the elementary strength theory for cracked beams forwarded by Herrmann and co-workers, coupled with dimensional considerations and a finite element calibration. The expressions given here are valid for the case when the crack has propagated through the flange and into the web of the beam. The simple expressions are accurate to within 5% of detailed finite element calculations for the range of practical applicability. To further demonstrate the validity of the stress intensity factor expression, we measured fracture loads for cracked polymethyl methacrylate (PMMA) I-beams in four-point flexure. Using the failure loads and our expression for the stress intensity factor, we deduce the fracture toughness. The fracture toughness so-obtained results in excellent fracture correlation for the cracked I-beams.

The effects of crack face boundary conditions on the fracture mechanics of piezoelectric solids are studied. In previous works the assumption that in addition to being traction free, a slit crack is impermeable to electric fields has yielded the appealing result that an applied electric field can retard crack growth. Here, more accurate crack face boundary conditions regarding the electric fields are employed by analyzing a permeable elliptical flaw in a piezoelectric solid, and the results illustrate that the impermeable assumption can lead to significant errors regarding the effects of the electric fields on crack propagation based on an energy release rate criterion. The relatively simple closed form expressions that are obtained can be used as benchmark solutions for further finite element analysis of piezoelectric crack problems.