BACKGROUND Finite element simulation has been used in last years for analysing the biomechanical performance of post-core restorations in endodontics, but results of these simulations have been interpreted in most of the works using von Mises stress criterion. However, the validity of this failure criterion for brittle materials, which are present in these restorations, is questionable. The obj...

Strength of rocks in the confined tension region, where minimum principal stress is tensile, has only infrequently been measured and not well understood. Quasi-static Brazilian tests under a range confining stresses (2.76 to 27.58 MPa) used determine strength sandstone region. The test results indicate that region was strong function intermediate stress: increasing significantly increased sands...

Determination of the borehole and fracture initiation positions is the main aim of a borehole stability analysis. A wellbore trajectory optimization with the help of the mud pressure may be unreasonable since the mud pressure can only reflect the degree of difficulty for the initial damage to occur at the wellbore rather than the extent of the wellbore damage. In this work, we investigate...

Experimental data have demonstrated that a strong relationship exists between the state parameter and peak strength dilatancy characteristics of sands. This paper proposes way reproducing this behaviour using modified Mohr-Coulomb failure criterion, which retains its simplicity while improving substantially modelling capabilities. The formulated constitutive model is calibrated for Nevada sand ...

Strength reduction finite element method (SRFEM) has been widely used to analyze the slope stability. Strength Reduction Factor (SRF) is yielded as the slope Factor Of Safety (FOS) when a running-though shear failure zone comes into being, in which the Plastic Element EQuivalent strain (PEEQ) is employed as the judgment of shear failure initiation in this paper. Moreover, the filed variable is ...

A rock failure criterion is very important for prediction of the ultimate strength in rock mechanics and geotechnics; it is determined for rock mechanics studies in mining, civil, and oil wellborn drilling operations. Also shales are among the most difficult to treat formations. Therefore, in this research work, using the artificial neural network (ANN), a model was built to predict the ultimat...

Abstract Extension fractures are typical for the deformation under low or no confining pressure. They can be explained by a phenomenological extension strain failure criterion. In past, simple empirical criterion fracture initiation in brittle rock has been developed. this article, it is shown that makes unrealistic strength predictions biaxial compression and tension. To overcome major limitat...

A new method for implicit integration of the Mohr-Coulomb non-smooth multisurface plasticity models is presented, and Koiter’s requirements are incorporated exactly within proposed algorithm. Algorithmic numerical complexities identified introduced by nonsmooth intersections surfaces; then, a projection contraction algorithm applied to solve classical Kuhn–Tucker complementary equations which p...

We present a two-dimensional analytical solution for the static stress field around rough interlocked interface under background stresses and its applications to faulting. The is derived using perturbation theory defined topography stresses. failure-ratio, which scales likelihood failure of bulk material interface, calculated adopting Coulomb criterion. compare model predictions with results ex...