Metal owns the ability of self-healing to some extent, and the ability of the internal crack healing is most desirable for improving the reliability of metal. A molecular dynamics simulation has been further developed to investigate the evolution of a nanoscale crack in body centred cubic Fe crystal under the conditions of heating or compressive pressure. When system temperature drops, the evol...

In this paper the line-spring model developed by Rice and Levy is used to obtain an approximate solution for a cylindrical shell containing a part-through surface crack. It is assumed that the shell contains a circumferential or axial semi-elliptic internal or external surface crack and is subjected to a uniform membrane loading or a uniform bending moment away from the crack region. To formula...

A transient _nite element analysis is carried out to provide insight into the low temperature dynamic material toughness versus crack tip relationship for high strength structural steels under intense stress pulse loading[ The problem analyzed here is plane strain fracture of an edge cracked specimen under plane wave loading conditions[ The _nite element formulation employed accounts for the e}...

BACKGROUND The health risks of crack cocaine smoking in public settings have not been well described. We sought to identify factors associated with public crack smoking, and assess the potential for a supervised inhalation facility to reduce engagement in this behavior, in a setting planning to evaluate a medically supervised crack cocaine smoking facility. METHODS Data for this study were de...

BACKGROUND Crack pipe sharing can increase health risks among people who use drugs, yet the reasons for sharing these pipes have not been well described. Therefore, we sought to identify the prevalence and correlates of crack pipe sharing among a community-recruited sample of people who use illicit drugs in Vancouver, a setting where crack pipes are provided at low or no cost. FINDINGS Data f...

abstract in the present article, effective parameters of the buoyant jets have been evaluated in the stagnant ambient fluid. the jet parameters, geometry parameters and environmental parameters are investigated. using dimensional analysis, a set of dimensionless functions was obtained. to achieve the exact functions, a physical model was built in the hydraulic laboratory of shahid chamran unive...

In this paper, the fatigue and fracture properties of bovine dentin are evaluated using in vitro experimental analyses. Double cantilever beam (DCB) specimens were prepared from bovine maxillary molars and subjected to zeroto-tension cyclic loads. The fatigue crack growth rate was evaluated as a function of the dentin tubule orientation using the Paris law. Wedge-loaded DCB specimens were also ...

For a crack in a structure, the crack driving force G is the reduction of the elastic energy in the structure, associated with the crack extending per unit area. In principle, G can be calculated by solving a boundary value problem. In practice, however, such a calculation is prohibitively difficult for integrated structures of complex architectures, diverse materials and small features. The ca...

Linear eigenvalue analysis of cracked cylindrical shells under combined internal pressure and axial compression is carried out to study the effect of crack type, size and orientation on the buckling behavior of cylindrical thin shells. Two types of crack are considered; through crack and thumbnail crack. Our calculations indicate that depending on the crack type, length, orientation and the int...

This paper presents an experimental investigation to clarify shear cracking behavior of reinforced concrete beams. The effects of the various influential parameters on the spacing between shear cracks and the relationship between shear crack width and stirrup strain at the intersection with shear cracks were carefully investigated. It was found that shear crack width proportionally increases wi...