radial crack
Recently Published Documents


TOTAL DOCUMENTS

105
(FIVE YEARS 4)

H-INDEX

16
(FIVE YEARS 0)

Author(s):  
Damla Torul ◽  
Mehmet Melih Omezli ◽  
Ferhat Ayranci ◽  
Damla Aydin Altay

Dentists are vulnerable to occupational injuries associated with dental procedures, and to their work environment. Lack of appropriate and safe working conditions can put dental professionals at risk of injuries, the majority of which are musculoskeletal, especially in the wrist. This report presents a case of a radial crack in the wrist of a dental student which occurred as a complication of a tooth extraction procedure. Also, emphasises the need for education about workplace risks and hazards, starting at the undergraduate level, to promote prevention of occupational injuries.



2020 ◽  
Vol 142 (5) ◽  
Author(s):  
Abdulmohsen M. Alqahtani ◽  
Thamer K. Albulayhid ◽  
Mutlaq N. Alotaibi ◽  
Ibrahim M. Alarifi ◽  
Tarek M. A. A. EL-Bagory

Abstract The previous research review of piping systems revealed that the plastic pipe companies suffered from many problems in natural gas pipeline systems. One of the most significant problems that appeared in the piping systems are external cracks due to manufacturing processes, welding technique, and installation processes. The principal goal of the present experimental study is to predict the crack growth behavior and energy release rate of cracked ring specimens made from high-density polyethylene (HDPE) under different crack position angles and various crosshead speeds. The effect of loading rate on the external radial crack at different crack position angles plays an important role in the prediction of fracture behavior of plastic pipe materials. For this reason, it is necessary to conduct a study for the fracture analysis of pipe ring specimens under tension loading with double external cracks at constant radial crack length to width ratio equal a/W = 0.5. A precracking machine is designed especially in the present experimental study to simulate the actual radial cracks at outer surface of pipe ring specimens. The effects of crosshead speed and crack position angle revealed a significant effect on the energy release rate and maximum applied load under tensile load.



2020 ◽  
Vol 2020 ◽  
pp. 1-18
Author(s):  
Xudong Li ◽  
Kewei Liu ◽  
Jiacai Yang

The high in situ stress can significantly affect the blast-induced rock fragmentation and cause difficulties in deep mining and civil engineering where the drilling and blasting technique is applied. In this study, the rock crack propagation induced by blasting under in situ stress is first analyzed theoretically, and then a numerical model with a decoupled charge in LS-DYNA is developed to reveal how the initiation and propagation of rock cracks are under high in situ stress. Through simulation, the mechanisms of blast-induced crack evolution under various hydrostatic pressures and nonhydrostatic pressures are investigated, and the differences in crack evolution with specific decoupling coefficients are compared. According to the simulation, three damage zones, i.e., the crushed zone, the nonlinear fracture zone, and the radial crack propagation zone, are formed, and the radial crack evolution is greatly suppressed by the high in situ stress which has no much influence on the crack propagation in the crushed and the nonlinear fracture zones. The velocity of crack propagation is slightly reduced, and the process of crack propagation is stopped early when the rock is subjected to high in situ stress. Furthermore, the numerical analysis indicates that the crack grows preferentially in the direction of maximum principal stress, and the radial crack propagation is predominantly controlled by the preloaded pressure, which is vertical to the crack propagation direction. Based on the numerical results, it is suggested that the optimal decoupling coefficients for rock cracking are 2.65, 1.87, 1.37, and 1.22 for 0, 10, 20, and 30 MPa, respectively. This study provides not only an analysis of the rock crack evolution under high in situ stress but also a reference for resolving excavation difficulties in deep mining.



2020 ◽  
Author(s):  
Yan Yan ◽  
Zhichuan Guan ◽  
Yuqiang Xu ◽  
Xuan Zhang ◽  
Weijun Yan


2019 ◽  
Vol 80 (12) ◽  
pp. 341-345
Author(s):  
Ismoil Ibragimovich Safarov ◽  
◽  
Мuxsin Khudoyberdiyevich Тeshaev ◽  
Zafar Ixtiyorovich Boltaev ◽  
Nurillo Raximovich Kulmuratov ◽  
...  


Author(s):  
Abdulmohsen M. Alqahtani ◽  
Thamer K. Albulayhid ◽  
Mutlaq N. Alotaibi ◽  
Ibrahim M. Alarifi ◽  
Tarek M. A. A. El-Bagory

Abstract The previous research review of piping systems revealed that the plastic pipes companies suffered from many problems in natural gas pipeline systems. One of the most significant problems appeared in the piping systems are external cracks due to manufacturing processes, welding technique and installation processes. The principal goal of the present experimental study is to predict the crack growth behavior and energy release rate of cracked ring specimen made from high-density polyethylene (HDPE) under different crack position angles and various crosshead speeds. The effect of loading rate on the external radial crack at different crack position angles plays an important role in the prediction of fracture behavior of plastic pipe materials. For this reasons, it is necessary to conduct a study for the fracture analysis of pipe ring specimen under tension loading with double external cracks at constant radial crack length to width ratio equal a/W = 0.5. Pre-cracking machine is designed especially in the present experimental study to simulate the actual radial cracks at outer surface of pipe ring specimens. The effects of crosshead speed and crack position angle are revealed a significant effect on the energy release rate and maximum applied load under tensile load.



2019 ◽  
Vol 39 (14) ◽  
pp. 4011-4022 ◽  
Author(s):  
Yuri Kadin ◽  
Mehdi Mazaheri ◽  
Vadim Zolotarevskiy ◽  
Charlotte Vieillard ◽  
Mark Hadfield


2018 ◽  
Vol 136 (8) ◽  
pp. 47080
Author(s):  
Kang Yang ◽  
Bin Yang ◽  
Jinling Wang ◽  
Liang He ◽  
Yun Wan ◽  
...  


2018 ◽  
Vol 844 ◽  
pp. 435-458 ◽  
Author(s):  
Niall J. O’Keeffe ◽  
Herbert E. Huppert ◽  
P. F. Linden

Hydraulic fracturing is a procedure by which a fracture is initiated and propagates due to pressure (hydraulic loading) applied by a fluid introduced inside the fracture. In this study, we focus on a crack driven by an incompressible Newtonian fluid, injected at a constant rate into an elastic matrix. The injected fluid creates a radial fracture that propagates along a plane. We investigate this type of fracture both theoretically and experimentally. Our experimental apparatus uses a brittle and transparent polyacrylamide hydrogel matrix. Using this medium, we examine the rate of radial crack growth, fracture aperture, shape of the crack tip and internal fluid flow field. Our range of experimental parameters allows us to exhibit two distinct fracturing regimes, and the transition between these, in which the rate of radial crack propagation is dominated by either viscous flow within the fracture or the material toughness. Measurements of the profiles near the crack tip provide additional evidence of the viscosity-dominated and toughness-dominated regimes, and allow us to observe the transition from the viscous to the toughness regime as the crack propagates. Particle image velocimetry measurements show that the flow in the crack is radial, as expected in the viscous regime and in the early stages of the toughness regime. However, at later times in the toughness regime, circulation cells are observed in the flow within the crack that destroy the radial symmetry of the flow field.



Sign in / Sign up

Export Citation Format

Share Document