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

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.

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Evaluation of Generalized MTS Criterion for Mixed-Mode Fracture of Polyurethane Materials

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.577-578.117 ◽

2013 ◽

Vol 577-578 ◽

pp. 117-120 ◽

Cited By ~ 1

Author(s):

Radu Negru ◽

Liviu Marşavina ◽

Hannelore Filipescu

Keyword(s):

Mixed Mode ◽

Full Range ◽

Experimental Results ◽

Mode I ◽

Mode Ii ◽

Mixed Mode Fracture ◽

Pure Mode ◽

Bend Specimen ◽

Mode Fracture ◽

Fracture Tests

Using the asymmetric semi-circular bend specimen (ASCB) a set of mixed-mode fracture tests were carried out in the full range from pure mode I to pure mode II. The tests were conducted on two polyurethane materials characterized by different properties. The fracture parameters were obtained from experiments and are compared with the predictions based on the generalized MTS criterion (GMTS). The agreement between the experimental results and those predicted based on the GMTS criterion is discussed finally.

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

Applied Sciences ◽

10.3390/app11041652 ◽

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.

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

Processes ◽

10.3390/pr7020070 ◽

2019 ◽

Vol 7 (2) ◽

pp. 70 ◽

Cited By ~ 3

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.

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On the use of embedded discontinuity elements with crack path continuity for mode-I and mixed-mode fracture

Engineering Fracture Mechanics ◽

10.1016/s0013-7944(01)00108-4 ◽

2002 ◽

Vol 69 (6) ◽

pp. 661-686 ◽

Cited By ~ 96

Author(s):

J. Alfaiate ◽

G.N. Wells ◽

L.J. Sluys

Keyword(s):

Mixed Mode ◽

Crack Path ◽

Mode I ◽

Mixed Mode Fracture ◽

Mode Fracture

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Analysis of Inclined Cracks in Thin-Walled Circular Tube under Mixed-Mode I + II Fracture

Proceedings ◽

10.3390/icem18-05421 ◽

2018 ◽

Vol 2 (8) ◽

pp. 517 ◽

Cited By ~ 1

Author(s):

Boy Raymond Mabuza

Keyword(s):

Fracture Mechanics ◽

Mixed Mode ◽

Crack Tip ◽

Theoretical Models ◽

Mode I ◽

Mixed Mode Fracture ◽

Shear Stresses ◽

Inclined Crack ◽

Mode Fracture ◽

Thin Walled

This paper provides a study on mixed-mode fracture mechanics in thin-walled tube which is subjected to tension, shear and torsion loading. This type of loading causes an inclined crack to develop and generate a mixture of normal and shear stresses ahead of a crack tip. The stress state ahead of a crack tip is frequently based on mixed-mode type of interactions which designate the amplitude of the crack tip stresses. The analytical expressions for the stress intensity factors for mixed-mode I + II approach are presented. The Paris law for mixed-modes I + II has been discussed. Mixed-mode fracture mechanics is used with theoretical models to predict the path of crack growth when an inclined crack is subjected to a combination of mode I and mode II deformations. The torque at which crack propagation can be expected has been determined. The numerical calculations have been carried out by using MATLAB code. The results are good and could be useful for companies working with thin-walled circular tubes.

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Comparison of mixed mode fracture criteria in finite element analysis for matrix crack density estimation of laminated composites

Journal of Composite Materials ◽

10.1177/0021998320948246 ◽

2020 ◽

Vol 55 (2) ◽

pp. 277-289

Author(s):

Mingqing Yuan ◽

Haitao Zhao ◽

Li Tian ◽

Boming Zhang ◽

Yanzhi Yang ◽

...

Keyword(s):

Finite Element Analysis ◽

Finite Element ◽

Density Estimation ◽

Mixed Mode ◽

Crack Density ◽

Mode I ◽

Mixed Mode Fracture ◽

Fracture Criteria ◽

Element Analysis ◽

Mode Fracture

A mixed mode crack density estimation method based on the finite element analysis (FEA) for laminated composites is proposed and verified in this paper. The damaged properties of cracked ply are obtained using semi-analytical micro-mechanical method for the first time. The piecewise functions of the mode I and mode II energy release rates involving crack density are given based on Griffith’s energy principle and discrete damage mechanics (DDM). Any mixed mode fracture criteria could be simply applied to the FEA of the structure to calculate the initiation and evolution of the micro-cracks in the laminate. Mode I criterion, power law and B-K criterion are applied in the numerical examples to compare their performances in the crack density estimation. It has been concluded that the accuracy of the fracture toughness is more important than the choice of fracture criterion in crack density estimation.

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