On toughening by microcracks

Shum, David K. M.; Hutchinson, John W.

doi:10.1016/0167-6636(90)90032-b

Cited by 62 publications

(23 citation statements)

References 11 publications

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“…19), which act as stress relievers and impose a dilatant closure field on the crack. This phenomenon is an open research topic in the field of fracture of polycrystalline materials and quantitative prediction techniques are not well-established due to the extremely complex nature of the phenomenon [28,29]. As argued in [30], (c) ASME experimental techniques such as TEM are affected by detectability limitations, while theoretical models cannot fully clarify the mechanical degradation produced by the formation and interaction of microcraks.…”

Section: Grain Size Effect On Time-to-failure and Fracture Behaviourmentioning

confidence: 99%

Peridynamic Modeling of Granular Fracture in Polycrystalline Materials

Meo

Zhu

Öterkuş

2016

Journal of Engineering Materials and Technology

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A new peridynamic formulation is developed for cubic polycrystalline materials. The new approach can be a good alternative to traditional techniques such as finite element method and boundary element method. The formulation is validated by considering a polycrystal subjected to tension loading condition and comparing the displacement field obtained from both peridynamics and finite element method. Both static and dynamic loading conditions for initially damaged and undamaged structures are considered and the results of plane stress and plane strain configurations are compared. Finally, the effect of grain boundary strength, grain size, fracture toughness and grain orientation on time-to-failure, crack speed, fracture behaviour and fracture morphology are investigated and the expected transgranular and intergranular failure modes are successfully captured. To the best of the authors' knowledge, this is the first time that a peridynamic material model for cubic crystals is given in detail.

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Section: Grain Size Effect On Time-to-failure and Fracture Behaviourmentioning

confidence: 99%

Peridynamic Modeling of Granular Fracture in Polycrystalline Materials

Meo

Zhu

Öterkuş

2016

Journal of Engineering Materials and Technology

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“…The model of discrete distributed microcracks around the main crack tip is often used to analyse the interaction between the main crack and microcracks due to the fact that the model can be accurately concerned with the orientation, position and size of the microcracks [2][3][4]. There is no question that the method to analyse the problem of interaction of the main -microcrack is of considerable significance for obtaining more accurate results as determined by [4].…”

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confidence: 99%

Simulating interaction of main-microcrack with dislocation arrays

1994

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Recently, much attention has been given to explaining that the macrocrack is shielded or antishielded by transformation strain point and impurity, especially by microcracking within the macrocrack tip region [1]. The model of discrete distributed microcracks around the main crack tip is often used to analyse the interaction between the main crack and microcracks due to the fact that the model can be accurately concerned with the orientation, position and size of the microcracks [2][3][4]. There is no question that the method to analyse the problem of interaction of the main -microcrack is of considerable significance for obtaining more accurate results as determined by [4]. Now a method to simulate interaction of main -microcracks with dislocation arrays is presented and it shows a higher accuracy.Muskhelishvili [5] gave the analytical function formula for plane elasticity; the stress and displacement components are ~= + % = 2[~(z) + ¢(z)] ~ + i ~,~ = t~(z ) + f~(z ) + (-z-z )t~'(z ) 2kt ~---~ (ux -iu,) = ~c~(z ) = f2(z ) -(7-z )df (z )(i) For the edge dislocation in an infinite body, shown in Fig. 1, ~p(z) and f~(z) are [6] ~t B -rci(1 + k) (bx + iby) where b and b are the two components of the edge dislocation, and li is shear modulus, ~ = 3-'4v for plane strain and (3-v)/(l+v) for plane stress. Int Journ of Fracture 68 (1994) R 4 8Simulating the semi-infinite crack (main crack) and microcracks (see Fig. 2) with arrays of dislocation, and supposing the length of all microcracks is 2 unit without generality, we have a singular integral equation of the main crack asTo make the transform u --1 ~--u + l ' ( -1 % u % 1)t --1 ~= t + l ' ( -l < t < 1)(2) is put into a suitable form for numerical solution 7 _(,m ~._(,,m u2 t ^ u.. ( u ) + o~, , .( u ) = E " " ) ( t ) d t + where 2(u -+-1) h(u,t) --t ÷ l 2ilm(z --s)

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Macrocrack interacting with microcrack on the interface

1995

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The problem of interaction between macrocrack and microcrack has become a topic studied by many researchers since Hutchinson [1] pointed out that the toughness of the material might be improved or reduced in the presence of the microcracks within the process zone [2][3][4][5][6][7][8][9][10]. Few works, however, discussed the problem of the macrocrack interacting with the microcrack on the interface, which often played a key role in laminated structures, especially in composite materials. This report will deal with this problem with the use of simulating the macrocrack and the microcrack with dislocation arrays.Muskhelishvili's theory described the stress and displacement components as [11] ~= + % = 214,(z) + ¢(z)] C1)where ~ is the shear modulus, ~: = 3-4v and (3-v)/(l+v) for plane strain and plane stress, respectively. ~(z) and ~(z) are the complex potentials. If a dislocation is on the interface (shown in Fig. 1), they are as follows [12] • (z) "-B(1 + ~*)/(z -s) n(z) = ~(1 -~*)/(z -s) 1+ o~ 1 (bx + iby) B -cz(i-~2) rciwhere c=(l+~:)/I.t, 9"=13 for y>0 and ~*=-1~ for y<0, s is the location of the edge dislocation, b x by are the two components of the edge dislocation, (x ~ are the Dunder's parameters. C2)Int Journ of Fracture 73 (1995) R72If we simulate the macrocrack and microcrack (shown in Fig. 2) with arrays of continuously distributed dislocations, a group of singular integral formula are obtained. The stress components of the interfacial macrocrack and microcrack are as followsTo make (3) a suitable form for the numerical solution, take the transform-1 o'= (r/)+to-xy (7/)= 2~rfliBc'~)(r/)+ °"°(~)d~ + -1 -1 (4) -I h2 (rl, t)BCW) ( t)dt (5) where in (5) 2 h~(u, ~) -z~_ ) _ s u-1 z~.O + Z(raa) --u+l' s= 4 h a (r/,t) = (z

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On toughening by microcracks

Cited by 62 publications

References 11 publications

Peridynamic Modeling of Granular Fracture in Polycrystalline Materials

Peridynamic Modeling of Granular Fracture in Polycrystalline Materials

Simulating interaction of main-microcrack with dislocation arrays

Macrocrack interacting with microcrack on the interface

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