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.

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

Proceedings ◽  
2018 ◽  
Vol 2 (8) ◽  
pp. 517 ◽  
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.

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.

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

2013 ◽  
Vol 577-578 ◽  
pp. 117-120 ◽  
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.

Experimental and Numerical Investigation of the Mixed-Mode Delamination of PAN Based Carbon/Epoxy Composite Using Modified Arcan Fixture

2011 ◽  
Vol 471-472 ◽  
pp. 880-885 ◽  
Author(s):  
M. Ziaee ◽  
Naghdali Choupani
Keyword(s):  
Fracture Toughness ◽  
Stress Intensity ◽  
Mixed Mode ◽  
Sliding Mode ◽  
Epoxy Composite ◽  
Mode I ◽  
Mode Ii ◽  
Mixed Mode Fracture ◽  
Pure Mode ◽  
Element Analysis

The present research examines analytically and experimentally the mode-I and mode-II and mixed mode-Interlaminar fracture toughness of PAN based carbon/epoxy composite. A modified Arcan fixture, well-suited for the study of the behavior of used composite assemblies, was developed in order to focus on the analysis of the fracture behavior of the material. The edge effects are minimized by using an appropriate design of the substrates so that experimental results give reliable data. Also the mode-I and mode-II stress intensity factors were computed for different crack lengths and load orientation angles using finite element analysis. The numerical results show that the modified Arcan specimen is able to provide pure mode-I, pure mode-II and any mixed mode loading conditions. It is shown that the results obtained from the fracture tests are consistent very well with mixed mode fracture theories. Obtained results indicated that fracture toughness and stress intensity factor for sliding mode enhanced up when the loading angle increased. Mechanism of fracture and toughening were examined by using scanning electron microscopy.

Mixed Mode Fracture in Electronic Packages

1996 ◽  
Vol 445 ◽  
Author(s):  
W. O. Soboyejo ◽  
V. Sinha ◽  
V. Kenner
Keyword(s):  
Fracture Toughness ◽  
Mixed Mode ◽  
Mode I ◽  
Mode Ii ◽  
Mixed Mode Fracture ◽  
Electronic Packages ◽  
Mixed Mode Loading ◽  
Molding Compound ◽  
Mode Fracture ◽  
Mode Ii Fracture Toughness

AbstractIn this paper, mixedmode (mode I + mode II) fracture toughness data are presented for the prediction of molding compound (silica filled epoxy resin) failure. The stresses necessary to cause the package cracking under mixed mode loading are experimentally determined. Measured toughness values are presented as a function of modemixity and temperature

scholarly journals Mixed Mode I/II Fracture Analysis of Bi-Material Adhesive Bonded Joints Using a Novel Short Beam Specimen

2021 ◽  
Vol 11 (11) ◽  
pp. 5232
Author(s):  
Mohammad Reza Mohammad Aliha ◽  
Hadi Ghesmati Kucheki ◽  
Mirmilad Mirsayar
Keyword(s):  
Mixed Mode ◽  
Fracture Initiation ◽  
Shear Mode ◽  
Mode I ◽  
Beam Specimen ◽  
Pure Mode ◽  
Inclined Crack ◽  
Cracking Behavior ◽  
Test Configuration ◽  
Fracture Parameters

Until now, some test specimens with different shapes and loading mechanisms have been utilized for investigating the cracking behavior of adhesive bounded joints. In this research, using a novel test configuration called adhesive short bend beam specimen containing an inclined crack and loaded by three-point bending, mixed mode I/II fracture parameters of a crack initiated in the adhesive part is studied. Compared to other test methods, the specimen used in this research needs a lesser amount of material and the fracture test can be performed easily. A large number of finite element models of this specimen were analyzed using ABAQUS code to study the effect of adhesive and adherent type, and also the crack length and loading span distance on KI, KII, T-stress and fracture initiation direction under different mode mixities. The results showed that the fracture parameters (and in particular the shear mode component) are sensitive to the type and location of adherent in the bounded joint; however, the shape and size of fracture plastic zone is not affected noticeably by the type of adhesive-adherent materials. It was also shown that the complete mode mixities ranging from pure mode I to pure mode II can be introduced for adhesive bounded joints using the proposed test specimen and therefore the specimen is a good candidate test configuration for investigating the mixed mode I/II fracture behavior of adhesive bounded joints.

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