scholarly journals Experimental and Numerical Analysis of Mode I Fracture Process of Rock by Semi-Circular Bend Specimen

Mathematics ◽  
2021 ◽  
Vol 9 (15) ◽  
pp. 1769
Author(s):  
Peng Xiao ◽  
Diyuan Li ◽  
Guoyan Zhao ◽  
Meng Liu
Keyword(s):  
Crack Propagation ◽  
Propagation Velocity ◽  
Fracture Process ◽  
Process Zone ◽  
Peak Load ◽  
Development Stage ◽  
Displacement Curve ◽  
Initial Development ◽  
Crack Propagation Velocity ◽  
Scb Specimen

The semi-circular bend (SCB) specimen is widely used to measure fracture toughness of brittle materials such as rock. In this work, the stress field, fracture process zone (FPZ), and crack propagation velocity of SCB specimen are analyzed during the fracture process of rock specimens. The FPZ of specimen is obtained by experimental and numerical methods under a three-point bend test. The stress concentration zones of specimen present a heart shape at peak load points. FPZ forms before macro fracture occurs. The macro fracture form inside FPZ in a post-peak region of a load–displacement curve. The crack propagation process of specimen include two stages, namely the rapid crack initial development stage, and the final crack splitting stage. The maximum crack propagation velocity of specimen is about 267 m/s, and the average crack propagation velocity is about 111 m/s.

scholarly journals Study on Crack Propagation of the Tunnel Model under Dynamic Loading

2021 ◽  
Vol 2021 ◽  
pp. 1-18
Author(s):  
Chengxiao Li ◽  
Yuantong Zhang ◽  
Peng Xu ◽  
Chen An
Keyword(s):  
Fracture Toughness ◽  
Crack Propagation ◽  
Dynamic Fracture ◽  
Propagation Velocity ◽  
Fracture Process ◽  
Test Results ◽  
Crack Propagation Velocity ◽  
Propagation Law ◽  
Initial Fracture ◽  
The Impact

Crack defects make it difficult to predict the dynamic fracture of tunnel specimens under an impact load. To study the impact of the velocity and crack location on a roadway under dynamic load, specimens with tunnel-type voids were made using polymethyl methacrylate. The split-Hopkinson bar was used as the loading method, and a digital laser dynamic caustics system was used to observe the fracture process of the specimens. The dynamic fracture process was evaluated by the crack propagation velocity, displacement, and dynamic stress intensity factor. To predict and verify the test results, ABAQUS was used to simulate the test process. It was found that the results of the simulated combinations of the crack propagation path and initial fracture toughness change law are consistent with the test results. The initial fracture toughness and the peak value of the crack propagation velocity increased with the increase of the impact velocity. The crack propagation law and trajectory were affected by the location of the prefabricated cracks.

The influence of crack propagation velocity on the energy content of the fracture process

1976 ◽  
Vol 12 (5) ◽  
pp. 518-525 ◽  
Author(s):  
A. P. Bobryakov ◽  
G. N. Pokrovskii ◽  
B. N. Serpeninov
Keyword(s):  
Crack Propagation ◽  
Propagation Velocity ◽  
Fracture Process ◽  
Energy Content ◽  
Crack Propagation Velocity

Crack propagation velocity and fracture toughness of hydroxyl-terminated polybutadiene propellants: experiments and simulations

2021 ◽  
pp. 108034
Author(s):  
Tingyu Wang ◽  
Jinsheng Xu ◽  
Hui Li ◽  
Wu Ding ◽  
Jiaming Liu ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Crack Propagation ◽  
Propagation Velocity ◽  
Crack Propagation Velocity

Experimental study of unstable crack propagation velocity for X80 pipeline steel

2018 ◽  
Vol 42 (4) ◽  
pp. 805-817
Author(s):  
Shaohua Dong ◽  
Lai bin Zhang ◽  
Hewei Zhang ◽  
Yinuo Chen ◽  
Hang Zhang
Keyword(s):  
Experimental Study ◽  
Crack Propagation ◽  
Propagation Velocity ◽  
Pipeline Steel ◽  
X80 Pipeline Steel ◽  
Unstable Crack ◽  
Crack Propagation Velocity

Study on Interfacial Crack Propagation and Fracture between Embedded Steel and HSHPC

2007 ◽  
Vol 348-349 ◽  
pp. 853-856
Author(s):  
Shan Suo Zheng ◽  
Lei Li ◽  
Guo Zhuan Deng ◽  
Liang Zhang
Keyword(s):  
Crack Propagation ◽  
High Performance ◽  
Fracture Process ◽  
Fracture Process Zone ◽  
High Performance Concrete ◽  
Process Zone ◽  
Interfacial Crack ◽  
High Strength ◽  
Interfacial Fracture ◽  
Softening Process

Steel reinforced high strength and high performance concrete (SRHSHPC) specimens were experimented to study the mechanical behaviors between steel and concrete interface. In experiment, interfacial bond softening process was observed, which can be explained in terms of damage along the interface, leading to progressive reduction of shear transfer capability between steel and high strength and high performance concrete (HSHPC). In this paper, bond softening process along the interface is considered in the analysis of crack-induced debonding. Interfacial bond-slip mechanism between steel and HSHPC is studied in detail based on fracture mechanics. With the help of acoustic emissions technology, the crack propagation in the interlayer was observed, thus the interfacial crack propagation and fracture model is set up. Under the assumption that the interlayer is weak concrete compared with concrete matrix, the stress field as well as displacement field around the crack tip is deduced. The characteristics of interfacial fracture process are discussed and a model for interfacial fracture process zone is built up. With this model, the size of fracture process zone can be derived. At last, the influence of the fracture process zone on interfacial fracture toughness is determined using critical fracture toughness. All these may contribute to improvement of theory for SRHSHPC composite structure.

The Calculation of Stress Intensity Factors and the Analysis of Propagation Characteristic of Crack at Hole

2011 ◽  
Vol 250-253 ◽  
pp. 1856-1861
Author(s):  
Li Jun Lu ◽  
Jian Ping Liu ◽  
Zhong Mei Li
Keyword(s):  
Stress Intensity ◽  
Crack Propagation ◽  
Stress Intensity Factors ◽  
Propagation Velocity ◽  
Propagation Characteristic ◽  
Propagation Model ◽  
Intensity Factors ◽  
Crack Propagation Velocity ◽  
Guyed Mast ◽  
Shape And Size

This paper focusing on the crack at hole of guyed-mast’s ear-plate connecting cables and shaft of guyed-mast, adopting two degree of freedom crack propagation model, track the crack propagation according to the increment of the deepest point and the surface point on the crack front of crack at hole of guyed-mast’s ear-plate. The stress intensity factors of I,II and III type crack with given shape and size have been calculated via finite element method, and a numerical method of calculating stress intensity factors with any shape and size crack has been proposed; furthermore according to modified I, II and III type compound crack propagation velocity formula on the basis of Paris crack propagation velocity formula, we analyzed the changing of crack shape parameter a/c with crack size parameter a/T of crack at hole of ear-plate connecting cable and shaft of guyed-mast by numerical integration method and obtained the propagation characteristic.

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