The Influence of the Chosen Type of Form Lubricator in the Form for Cement Paste with Fly Ash on the Fracture Process Zone

2017 ◽  
Vol 731 ◽  
pp. 92-97
Author(s):  
Barbora Mužíková ◽  
Pavel Padevět
Keyword(s):  
Fly Ash ◽  
Crack Growth ◽  
Cement Paste ◽  
Fracture Process ◽  
Fracture Process Zone ◽  
Process Zone ◽  
The Other ◽  
Mode Ii ◽  
Air Bubbles ◽  
The Real

This paper is focused on the cracks growth in mode II of specimens made of cement paste with fly ash. Three prescriptions were made for testing in mode II, during the making air bubbles arose at the bottom of the specimen that were lubricated with oil. These little caverns can have an influence on the growth of the cracks in the fracture process zone. On the other side, specimens that were lubricated with a wax, no caverns were observed. There are complex mechanisms of crack growth in the fracture process zone, cavern or inertial elements have a fundamental effect on the success of the real tests in mode II. Specimens lubricated with wax have a 50 % higher successful running of the test than those, whose forms were lubricated with the oil.

Assessment of the fracture process zone in rocks using digital image correlation technique: The role of mode-mixity, size, geometry and material

2019 ◽  
Vol 29 (4) ◽  
pp. 646-666 ◽  
Author(s):  
M Moazzami ◽  
MR Ayatollahi ◽  
A Akhavan-Safar
Keyword(s):  
Digital Image Correlation ◽  
Fracture Process ◽  
Fracture Process Zone ◽  
Process Zone ◽  
Specimen Size ◽  
Image Correlation ◽  
Mode I ◽  
Mode Ii ◽  
Mode Mixity ◽  
Zone Length

This paper presents an experimental research on the length and shape of the fracture process zone of rocks under mode I, mixed mode (I + II) and mode II loading conditions for different geometries of cracked specimens made of two types of rocks, using the digital image correlation approach. Single edge notch bending (SENB) and semi-circular bend specimens are the two geometries considered. In order to investigate the effect of the specimen size on the fracture process zone length, rocks with three different sizes are produced and tested. To investigate the effect of the mode mixity on the fracture process zone length of marble and sandstone, the specimens are tested under different modes of loading. According to the experimental results, it is found that the fracture process zone length changes with mode ratio, specimen size, geometry and the material properties. The fracture process zone length increases when the mode of loading moves from mode I to mode II. Experimental results also show that fracture process zone becomes longer for specimens with larger sizes. The fracture process zone is also affected by the specimen geometry.

Does the Process Zone Control Crack Growth?

1992 ◽  
Vol 45 (8) ◽  
pp. 367-376 ◽  
Author(s):  
H. Abe´ ◽  
M. Saka ◽  
S. Ohba ◽  
T. Hashida
Keyword(s):  
Crack Growth ◽  
Main Crack ◽  
Fracture Process ◽  
Fracture Process Zone ◽  
Process Zone ◽  
Crack Tip ◽  
Compact Tension ◽  
Initial Crack ◽  
Zone Control ◽  
Notch Length

Fracture toughness tests were carried out by using small compact tension specimens of Westerly granite. Relation between the load-line displacement and the initial crack-tip separation changed from linear to nonlinear and then to linear again with increasing loading. The onset of the main crack growth was found to occur in a loading level at which the relation was nonlinear. This result disclosed that the onset of main crack growth in granite occurred without experience of the complete area under the tension-softening curve. The critical value of the initial crack-tip separation for onset of the main crack growth was obtained independently of the initial notch length. Also monitoring of the growth of the fracture process zone by ultrasonic technique showed that its length related with the crack-tip separation independently of the initial notch length. By combining the results just mentioned, it was concluded that the fracture process zone controlled the onset of the main crack growth.

Crack Growth Resistance of Ceramic Composite

1992 ◽  
Vol 287 ◽  
Author(s):  
Seijiro Hayashi ◽  
H. Baba ◽  
A. Suzuki
Keyword(s):  
Crack Growth ◽  
Fracture Process ◽  
Ceramic Composite ◽  
Fracture Process Zone ◽  
Process Zone ◽  
Crack Opening ◽  
Stable Crack Growth ◽  
Beam Specimen ◽  
Opening Displacement ◽  
Element Analysis

ABSTRACTFracture process zone in SiCw/Si3N4 ceramic composite was studied by a hybrid experimental-numerical analysis employing moire interferometry and finite element analysis. A chevron-notched, wedge-loaded double cantilever beam specimen was used to obtain a stable crack growth. The relation between crack closure stress and crack opening displacement which govern fracture process zone was obtained.

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