A reliable and cost effective two-phase methodology is proposed to predict crack propagation in generic two-dimensional structural components under complex fatigue loading. First, the fatigue crack path and its stress intensity factors are calculated in a specialized finite element software, using small crack increments. At each crack propagation step, the mesh is automatically redefined based ...

A method for determining the size of a crack induced by hydraulic fracturing is presented. The procedure is based on the measurement of the crack opening displacement and the fracture mechanics approach. The proposed method has been tested by conducting laboratory small-scale hydraulic fracturing tests on a granite. It is shown from the preliminary tests that the method provides a reasonable pr...

The one-point bend impact test has been used to investigate crack instability conditions for short loading times (as short as 2.5 p) in high strength steel. It was found that, in the range of loading rates investigated, no time-modified fracture criterion need be invoked. The resistance to crack extension may, however, increase significantly with crack growth due to the formation of even small ...

present work shows the numerical determination of fatigue crack opening and closure stress intensity factors of a C(T) specimen under variable amplitude loading using a finite element method. A half compact tension C(T) specimen, assuming plane stress constraint was used by finite element method covering the effects in two-dimensional (2D) small scale yielding models of fatigue crack growth und...

We calculate the effect of the nonsingular stress acting parallel to a crack (the “Tstress”) on edge dislocation nucleation at a crack loaded in Mode I. We find that this leads to crack size effect – that is, for small cracks (of order 100 atomic spacings or less), the T stress causes the critical load for dislocation nucleation (expressed in terms of the applied stress intensity factor) to dev...

The trajectory of a hydraulically driven crack near natural fractures, faults, and inhomogeneities has been studied using the complex variable hypersingular boundary element technique. The crack trajectories are presented for the cases of an oblique and a steeply inclined fault. It has been demonstrated that natural fractures, faults, and other inhomogeneities generate unstable fracture conÞgur...

A 2-dimensional, elastic-plastic finite element model has been developed to simulate plasticity induced crack closure in slanted and deflected cracks growing outside the small scale yielding (SSY) regime. The finite element model allows for contact between deformable surfaces to capture the complex contact interaction between the crack faces. Coulomb’s friction law has been used to model fricti...

Whether and how fracture mechanics needs to be modified for small length scales and in systems of reduced dimensionality remains an open debate. Here, employing in situ transmission electron microscopy, atomic structures and dislocation dynamics in the crack tip zone of a propagating crack in two-dimensional (2D) monolayer MoS2 membrane are observed, and atom-to-atom displacement mapping is obt...

A simple damage evolution model is proposed for a quasibrittle material in the framework of continuum damage mechanics. The model is used to obtain a closed form solution for a mode-III stationary crack under small scale damage conditions. It is found that the crack tip stress intensity factor is reduced, i.e., the crack is shielded by the damage. However, this shielding effect is completely of...