scholarly journals Experimental Study on Mixed Mode Fracture Behavior of Sandstone under Water–Rock Interactions

Processes ◽  
2019 ◽  
Vol 7 (2) ◽  
pp. 70 ◽  
Author(s):  
Wen Hua ◽  
Jianxiong Li ◽  
Shiming Dong ◽  
Xin Pan
Keyword(s):  
Mechanical Properties ◽  
Fracture Resistance ◽  
Mixed Mode ◽  
Degradation Mechanism ◽  
Mixed Mode Fracture ◽  
Pure Mode ◽  
Brazilian Disk ◽  
Tangential Strain ◽  
Mode Fracture

Water–rock interactions can significantly deteriorate the physical and mechanical properties of rocks, and it has been identified as one of the significant factors influencing the stability and safety of structures in rock–soil engineering. In this study, the fracture mechanical properties of sandstone under periodic water–rock interactions and long-term immersion have been studied with central cracked Brazilian disk specimens. The degradation mechanism of water–rock interactions was also studied using a scanning electron microscope (SEM). Finally, the generalized maximum tangential stress and generalized maximum tangential strain criteria were adopted to evaluate the experimental results. The results show that periodic water–rock interactions can remarkably affect the fracture resistance of sandstone. With the increase in the number of cycles, the pure mode I, pure mode II, and mixed mode fracture toughness decreases greatly, however, the values of KIf/KIC and KIIf/KIC decrease slightly. Furthermore, the fracture resistance of sandstone influenced by cyclic wetting–drying is more significant than long-term immersion. Moreover, the fracture criteria, which considers the effect of T-stress, can reproduce the test results very well.

scholarly journals Analysis of Mixed-Mode I/II/III Fracture Toughness Based on a Three-Point Bending Sandstone Specimen with an Inclined Crack

2021 ◽  
Vol 11 (4) ◽  
pp. 1652
Author(s):  
Xin Pan ◽  
Jiuzhou Huang ◽  
Zhiqiang Gan ◽  
Shiming Dong ◽  
Wen Hua
Keyword(s):  
Fracture Toughness ◽  
Mixed Mode ◽  
Mode I ◽  
Mixed Mode Fracture ◽  
Pure Mode ◽  
Inclined Crack ◽  
Tangential Strain ◽  
Mode Fracture ◽  
Fracture Parameters ◽  
T Stress

The crack-propagation form may appear as an arbitrary mixed-mode fracture in an engineering structure due to an irregular internal crack. It is of great significance to research the mixed-mode fracture of materials with cracks. The coupling effect of multiple variables (crack height ratio, horizontal deflection angle and vertical deflection angle) on fracture parameters such as the stress intensity factors and the T-stress are the key points in this paper. A three-point bending specimen with an inclined crack was proposed and used to conduct mixed-mode fracture research. The fracture parameters were obtained by finite element analysis, and the computed results showed that the pure mode I fracture and mixed-mode fractures (mode I/II, mode I/III and mode I/II/III) can be realized by changing the deflection angles of the crack. The pure mode I and the mixed-mode fracture toughness of sandstone were obtained by a series of mixed-mode fracture experiments. The experimental results were analyzed with the generalized maximum tangential strain energy density factor criterion considering T-stress. The results showed that the non-singular term T-stress in the fracture parameters cannot be ignored in any mixed-mode fracture research, and the generalized maximum tangential strain energy density factor criterion considering T-stress can better predict the mixed-mode fracture toughness than other criteria.

Mixed mode fracture analysis in a polymer mortar using the Brazilian disk test

2016 ◽  
Vol 154 ◽  
pp. 140-151 ◽  
Author(s):  
M. Martínez-López ◽  
G. Martínez-Barrera ◽  
L.C.S. Nunes ◽  
J.M.L. Reis ◽  
H.S. da Costa Mattos
Keyword(s):  
Mixed Mode ◽  
Fracture Analysis ◽  
Mixed Mode Fracture ◽  
Brazilian Disk ◽  
Mode Fracture ◽  
Polymer Mortar ◽  
Brazilian Disk Test ◽  
Disk Test

An Evaluation of the Compact Shear Specimen for Mixed Mode Fracture Studies

1983 ◽  
Vol 105 (4) ◽  
pp. 268-272 ◽  
Author(s):  
R. A. Riddle ◽  
R. D. Streit ◽  
I. Finnie
Keyword(s):  
Mixed Mode ◽  
Mode I ◽  
Mixed Mode Fracture ◽  
Pure Mode ◽  
Mode Fracture ◽  
Shear Specimen ◽  
Compact Shear ◽  
Detailed Computer ◽  
Almost All ◽  
Direction Opposite

A compact shear specimen configuration, consisting of three legs with the outer two loaded axially in a direction opposite to the inner one, has been used for several mixed-mode fracture studies. From a detailed computer analysis of this specimen, it is shown that the loading boundary conditions play an extremely important role in determining the state of stress at the crack tip. By simply changing the flexibility of the loading fixture, the specimen can be subjected to a range of mixed mode conditions from almost all Mode I to virtually pure Mode II. Data of other researchers are reviewed in light of this finding. It is shown that by applying loads obliquely to the outer legs pure Mode I loading may also be obtained with this specimen.

Application of the end loaded split and single-leg bending tests to the mixed-mode fracture characterization of wood

Holzforschung ◽  
2009 ◽  
Vol 63 (5) ◽  
Author(s):  
Jorge M.Q. Oliveira ◽  
Marcelo F.S.F. de Moura ◽  
José J.L. Morais
Keyword(s):  
Mixed Mode ◽  
Fracture Criterion ◽  
Experimental Tests ◽  
Bending Test ◽  
Mixed Mode Fracture ◽  
Pure Mode ◽  
Fracture Characterization ◽  
Bending Tests ◽  
Mode Fracture

Abstract This work describes the application of end loaded split and single-leg bending tests to the mixed-mode fracture characterization of wood. Experimental tests and numerical validation analyses were performed. A new data reduction scheme based on the crack equivalent concept is proposed. The method overcomes the difficulties inherent to these tests, such as crack length monitoring during propagation and influence of clamping conditions. The single-leg bending test is simpler to execute and provided accurate results. The obtained mixed-mode fracture energy is associated with the pure mode values and the obtained trend point to a linear fracture criterion as a candidate to describe the fracture behavior of the Pinus pinaster Ait. wood.

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