Objectives To determine the incidence of crack formation and propagation in apical root dentin after retreatment procedures performed using ProTaper Universal Retreatment (PTR), Mtwo-R, ProTaper Next (PTN), and Twisted File Adaptive (TFA) systems. Materials and Methods The study consisted of 120 extracted mandibular premolars. One millimeter from the apex of each tooth was ground perpendicula...

It is vital for the study of fracturing parameters optimal design and fluids rate forecast to calculate fracture propagation parameters accurately. In order to calculate fracture propagation accurately, in this paper, the model for calculating the value of energy release when the rock body collapses was established basing on catastrophe theory, considering that the collapse of fracturing rock b...

We describe a technique for improving the classification of fragmented cues for cracks. Evidence propagation on Bayesian networks represent search within the context of each cue. The algorithm was applied to a data-set of cracks, and results demonstrate that contextual classification of the cues leads to significantly improved error rates.

In-situ quasistatic tension experiments inside scanning electron microscope were performed to study shear-banding behaviors of a Zr-based bulk metallic glass composite with the 50% volume fraction dendritic phases. It was observed that shear band initiates at interface matrix and dendrites, then propagates in matrix. Dendrites change propagation direction bands or terminate within them. Both mo...

Every acceleration or deceleration causes inertia forces and as a consequence elastic waves. Of course, such dynamic loading situations often occur in structural applications of materials. The consequences of such dynamic loading on designing with ceramics are considered on the example of a new dynamic tension test. First, the test device is described, and the resulting loading situation is car...

A crack and its propagation is a challenging multiscale materials phenomenon of broad interest, from nanoscience to exogeology. Particularly in fracture mechanics, periodicities are of high scientific interest. However, a full understanding of this phenomenon across various physical scales is lacking. Here, we demonstrate periodic interlayer-mediated thin film crack propagation and discuss the ...

Crack propagation is tracked here with Digital Image Correlation analysis in the test case of two cracks propagating in opposite directions in polycarbonate, a material with high ductility and a large Fracture Process Zone (FPZ). Depending on the initial distances between the two crack tips, one may observe different complex crack paths with in particular a regime where the two cracks repel eac...

Paris law constants are commonly obtained with a well established procedure based on standard specimens, notched and pre-cracked. Pre-cracking produces through cracks with stable shapes, nearly straight, similar during all propagation. However, in several situations specimens with corner and surface cracks are recommended. In these cases cracks having significant propagation will continuously m...

Heterogeneous Al–Si microstructure comprising of sub-micron-scale Al dendrites and nanoscale fibrous eutectic was fabricated by processing as-cast Al-20wt.%Si alloy using laser rapid solidification. In situ tension tests explored high tensile strength (∼600 MPa) ductility (∼10%) strain hardening rate (∼7 GPa). Microstructural characterization revealed the plastic co-deformation mechanisms betwe...

The effect of preexisting subsurface cracks on the strength of lap splices was investigated. Ten full-scale beams with No. 11 (No. 36) bars and lap splice lengths of 33, 79, and 120 in. (838, 2007, and 3048 mm) were tested. The beams had mitigating features that prevented catastrophic failure upon propagation of the preexisting cracks, such as staggered splices and the presence of some reinforc...