scholarly journals NUMERICAL STUDY OF THE FRACTURING MECHANISM AROUND A BLASTHOLE AND INVESTIGATING THE EFFECT OF DISCONTINUITIES ON THE FRACTURE PATTERN

2020 ◽  
Vol 35 (4) ◽  
pp. 33-44
Author(s):  
Ali Reza Hajibagherpour ◽  
Hamid Mansouri ◽  
Mojtaba Bahaaddini
Keyword(s):  
Crack Propagation ◽  
Numerical Study ◽  
Distinct Element ◽  
Fracture Pattern ◽  
Discontinuity Surface ◽  
Open Pit ◽  
Propagation Mechanism ◽  
Normal Stiffness ◽  
Fractured Zones ◽  
Crack Propagation Mechanism

The mechanism of rock fragmentation around blastholes is of prior importance in the evaluation of drilling and blasting performance in open pit and underground mines. This paper aims to numerically investigate the crack propagation mechanism around a single blasthole using the distinct element method (DEM). In this study, two specimens with different borehole diameters were considered and the effects of the stress waves on their cracking mechanism were simulated. To validate the numerical model, the length of the radial cracks around each blasthole was measured and compared against an analytical fracture mechanics model. The fractured zones around the blasthole were also compared against previous experimental tests and good agreement was observed. The effect of a single discontinuity on the crack propagation mechanism was also studied and it was found that the discontinuity normal stiffness plays a significant role in the fractured zones around the blasthole. For low values of normal stiffness, the discontinuity surface acted as a free surface, and the shock wave was significantly reflected, while at high values of normal stiffness, cracks propagate across the discontinuity surface.

Influence of Hole Size on Crack Propagation Mechanism of Nano-Single Crystal Copper

2013 ◽  
Vol 328 ◽  
pp. 679-683
Author(s):  
Ge Li ◽  
Xian Qin Hou ◽  
Zhi Min Liu
Keyword(s):  
Molecular Dynamics ◽  
Crack Propagation ◽  
Hole Diameter ◽  
Propagation Mechanism ◽  
Hole Size ◽  
Single Crystal Copper ◽  
Dislocation Glide ◽  
Hole Position ◽  
Crack Propagation Mechanism ◽  
Dynamics Method

By molecular dynamics method, the tensile processes of nanosingle crystal copper with the crack front existence hole were simulated, and the effect of different hole size on crack propagation mechanism was analyzed. The results indicate that as the hole position remain unchanged, the hole diameter was more bigger, the atomic staggered and the crack tip deactivation were more obvious under tensile loads caused more dislocation glide appeared, meanwhile the number of slide-line was more and the trend of crack branch extend to hole position was more obvious.

scholarly journals Fatigue Crack Growth Behaviour and Role of Roughness-Induced Crack Closure in CP Ti: Stress Amplitude Dependence

Metals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1656
Author(s):  
Mansur Ahmed ◽  
Md. Saiful Islam ◽  
Shuo Yin ◽  
Richard Coull ◽  
Dariusz Rozumek
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Crack Growth ◽  
Crack Closure ◽  
Fatigue Cracks ◽  
Propagation Mechanism ◽  
Amplitude Dependence ◽  
Crack Growth Behaviour ◽  
Crack Propagation Mechanism ◽  
Cp Ti

This paper investigated the fatigue crack propagation mechanism of CP Ti at various stress amplitudes (175, 200, 227 MPa). One single crack at 175 MPa and three main cracks via sub-crack coalescence at 227 MPa were found to be responsible for fatigue failure. Crack deflection and crack branching that cause roughness-induced crack closure (RICC) appeared at all studied stress amplitudes; hence, RICC at various stages of crack propagation (100, 300 and 500 µm) could be quantitatively calculated. Noticeably, a lower RICC at higher stress amplitudes (227 MPa) for fatigue cracks longer than 100 µm was found than for those at 175 MPa. This caused the variation in crack growth rates in the studied conditions.

scholarly journals Investigation on Dynamic Propagation Characteristics of In-Plane Cracks in PVB Laminated Glass Plates

2016 ◽  
Vol 2016 ◽  
pp. 1-13 ◽  
Author(s):  
Xiaoqing Xu ◽  
Bohan Liu ◽  
Yibing Li
Keyword(s):  
Crack Propagation ◽  
Impact Loading ◽  
Crack Tip ◽  
Stress Waves ◽  
Critical Parameters ◽  
Propagation Mechanism ◽  
High Speed Photography ◽  
Laminated Glass ◽  
Propagation Characteristics ◽  
Crack Propagation Mechanism

Polyvinyl butyral (PVB) laminated glass has been widely used as an important component of mechanical and construction materials. Cracks on PVB laminated glass are rich in impact information, which contribute to its impact resistance design. In this paper, a three-dimensional (3D) numerical simulation model describing PVB laminated glass under impact loading is firstly established and validated qualitatively and quantitatively compared with the corresponding experimental results recorded by the high-speed photography system. In the meantime, the extended finite element method (XFEM) is introduced to analyze the crack propagation mechanism of laminated glass based on dynamic stress intensity factors (DSIFs) and propagations of stress waves. Parametric studies are then carried out to investigate the influence of five critical parameters, that is, plate dimension, crack length, impact energy, glass properties, and PVB properties, on crack propagation characteristics of laminated glass. Results show that the interaction between crack tip and stress waves as well as the propagations of stress waves corresponds to the fluctuations of DSIFs at crack tip. Both the structure and material variables are proven to play a very important role in glass cracking DSIFs and thus govern the crack propagation behavior. Results may provide fundamental explanation to the basic crack propagation mechanism on radial cracks in PVB laminated glass under impact loading conditions, thus to instruct its impact design improvement.

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