Cracks and craze lines are often observed in the enamel of human teeth, but they rarely cause tooth fracture. The present study evaluates fatigue crack growth in human enamel, and compares that to the fatigue response of sintered hydroxyapatite (HAp) with similar crystallinity, chemistry and density. Miniature inset compact tension (CT) specimens were prepared that embodied a small piece of ena...

A nominally straight crack of finite length is subjected to plane-strain loadings. A perturbation method is developed for calculating the stress-intensity factors, based on an asymptotic analysis of the governing hypersingular boundary integral equation for the crack-opening displacement. Known exact results for a shallow circular-arc crack are recovered, correct to second order in the small ge...

Recent finite-element results by S. Cl. Larsson and A. J. Carlsson suggest a limited range of validity to the ‘small scale yielding approximation’, whereby small crack tip plastic zones are correlated in terms of the elastic stress intensity factor, It is shown with the help of a model for plane strain yielding that their results may be explained by considering the non-singular stress, acting p...

A basic assumption often made in risk/reliability based inspection planning is that a Bayesian approach can be used. This implies that probabilities of failure can be updated in a consistent way when new information (from inspections and repairs) becomes available. The Bayesian approach and a no-crack detection assumption implies that the inspection time intervals usually become longer and long...

In this paper, the plates made of functionally graded material (FGM) with and without a crack are numerically simulated, employing the finite element method (FEM). The material property variations are defined to be fully continuous; therefore, the elements can be as small as required. For this purpose, variations of the material properties are applied in both the integration points and in the n...

The difference in the potential energy in an elastic three-dimensional domain with a V-notch with and without a small crack ( δΠ ) under a general mixed mode I+II+III loading is provided as an asymptotic series. It involves the V-notch edge stress intensity functions, the area of the formed crack, and special geometrical functions that can be pre-computed and tabulated. Importantly, the stress ...

The growth of a single cylindrical hole ahead of a blunt crack tip was studied using large deformation finite element analysis in three-point bend specimens with different precrack depth. The effect of small second phase particles was taken into account by incorporating Gurson’s constitutive equation. The effects of strain hardening and the initial distance from the hole to the crack tip were a...

We study mode-I fracture in lattices using atomistic simulations with randomly distributed bond lengths. By using a small parameter that measures the variation of the bond length between the atoms in perfect lattices and using a three-body force law, simulations reproduce the qualitative behavior of the beyond-steady-state cracks in the high-velocity regime, including reasonable microbranching....