A micromechanical fracture criterion accounting for in-plane and out-of-plane constraint

Mostafavi, Mahmoud; Smith, David J.; Pavier, Martyn J

doi:10.1016/j.commatsci.2011.04.023

Cited by 31 publications

(17 citation statements)

References 74 publications

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“…In the actual engineering structures, both in‐plane and out‐of‐plane constraints are generally existed. To describe the interaction between in‐plane and out‐of‐plane constraints and the overall level of constraints, a unified measure of constraint that is sensitive consistently to both is required 6,7 . However, the constraint parameters T , Q , A 2 , etc.…”

Section: Introductionmentioning

confidence: 99%

“…may not be sensitive equally to both in‐plane and out‐of‐plane constraints. Mostafavi et al 7–10 have suggested a unified constraint parameter ϕ that was defined as the size of the plastic region at the onset of fracture normalised by the plastic region size of a standard test: where A c is the plastic region area at fracture and A ssy is the reference plastic region area at fracture for a standard specimen in plane strain condition. They argued that both in‐plane and out‐of‐plane constraints have a similar effect on the plastic region size at fracture, and the parameter ϕ is equally sensitive to in‐plane and out‐of‐plane constraints.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Unified characterisation of in‐plane and out‐of‐plane constraint based on crack‐tip equivalent plastic strain

Yang

Wang

Xuan

et al. 2012

Fatigue Fract Eng Mat Struct

115

101

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Constraint can be divided into two conditions of in‐plane and out‐of‐plane, and each of them has its own parameter to characterize. However, in most cases, there exists a compound change of both in‐plane and out‐of‐plane constraint in structures, a unified measure that can reflect both of them is needed. In this paper, the finite element method (FEM) was used to calculate the equivalent plastic strain (ɛp) distribution ahead of crack tips for specimens with different in‐plane and out‐of‐plane constraints, and the FEM simulations based on Gurson–Tvergaard–Needleman (GTN) damage model and a small number of tests were used to obtain fracture toughness for the specimens with different constraints. Unified measure and characterisation parameter of in‐plane and out‐of‐plane constraints based on crack‐tip equivalent plastic strain has been investigated. The results show that the area APEEQ surrounded by the ɛp isoline ahead of crack tips can characterize both in‐plane and out‐of‐plane constraints. Based on the area APEEQ, a unified constraint characterisation parameter Ap was defined. It was found that there exists a sole linear relation between the normalised fracture toughness JIC/Jref and regardless of the in‐plane constraint, out‐of‐plane constraint and the selection of the ɛp isolines. The unified JIC/Jref−reference line can be used to determine constraint‐dependent fracture toughness of materials. The FEM simulations with the GTN damage model (local approach) can be used in obtaining the unified JIC/Jref−reference line for materials with ductile fracture.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Unified characterisation of in‐plane and out‐of‐plane constraint based on crack‐tip equivalent plastic strain

Yang

Wang

Xuan

et al. 2012

Fatigue Fract Eng Mat Struct

115

101

View full text Add to dashboard Cite

show abstract

“…However, the parameters mentioned previously are not equally sensitive to both constraints which exist in the engineering structures . So, a unified measure parameter of constraint which is equally sensitive to both is required …”

Section: Introductionmentioning

confidence: 99%

Unified correlation of in‐plane and out‐of‐plane constraints with fracture toughness

Yang

Wang

Xuan

et al. 2013

Fatigue Fract Eng Mat Struct

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In this paper, the specimens with different geometries and loading configurations were used to study the unified correlation of in‐plane and out‐of‐plane constraints with fracture toughness by using numerical simulation method. The results show that the unified constraint parameter Ap which was defined on the basis of the areas surrounded by the equivalent plastic strain isolines ahead of crack tip can characterise both in‐plane and out‐of‐plane constraints induced by different specimen geometries and loading configurations. A sole linear relation between the normalised fracture toughness JIC/Jref and Ap was obtained. The JIC/Jref ‐Ap line is a unified correlation line of in‐plane and out‐of‐plane constraints with fracture toughness of a material, and the constraint dependent fracture toughness of a material can be determined from the unified correlation line. The results also demonstrate that the out‐of‐plane constraint effect is related to the in‐plane constraint effect, and there exists interaction between them. The higher in‐plane constraint strengthens the out‐of‐plane constraint effect, whereas the lower in‐plane constraint is not sensitive to the out‐of‐plane constraint effect.

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“…Most of them focus on a point of damage initiation in the first ligament. In many cases (Aravas and McMeeking 1985a;Baaser and Gross 2003;Dahlberg 2004;Gao et al 2005;Hom and McMeeking 1989;Mostafavi et al 2011) a post-processing criterion was applied to obtain this point defined as critical. Tvergaard and Hutchinson (Tvergaard 2007;Tvergaard and Hutchinson 2002), Kim et al (2003) and Petti and Dodds (2005) employed a node-release technique to trace the crack growth after having fulfilled such a criterion.…”

Section: Micro-mechanical Models Of Ductile Crack Initiation and Propmentioning

confidence: 99%

“…Dahlberg (2004), Gu (2000), Tvergaard and Niordson (2008) as well as Gao et al (2005) and Kim et al (2003) resolved up to six discrete voids in the crack plane in front of the crack tip and found an influence of the shape of the voids, of an additionally added second row of voids, of the crack tip constraint and of strain gradient hardening. Petti and Dodds (2005), Tvergaard (2007) and Mostafavi et al (2011) incorporated up to 30 discrete voids in a single row in front of the crack tip. Gao et al (2005), Kim et al (2003), Petti and Dodds (2005), Tvergaard (2007), Tvergaard and Hutchinson (2002) defined a critical value of the ligament reduction ratio.…”

Section: Introductionmentioning

confidence: 99%

Ductile crack propagation by plastic collapse of the intervoid ligaments

et al. 2012

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In the present study ductile crack initiation and propagation is investigated by means of a micro-mechanical model under small-scale yielding conditions. Voids are resolved discretely in the fracture process zone where steep gradients occur during the loading history and are taken into accounted by a homogenized porous plasticity law elsewhere. The size of the region of discrete voids is not set a priori but is determined consistently. The results show that effective crack growth occurs by plastic collapse, i.e. purely geometric softening of the intervoid ligaments without incorporating material separation. Due to this mechanism a limit load exists coinciding with the maximum fracture toughness. In addition, it turns out that the shielding due to the growth of voids around the crack plane has a considerable influence on the computed R-curves compared to models neglecting this effect. Depending on the void arrangement a diffuse softening zone or even crack branching is observed. A comparison with experimental data from literature indicates that plastic collapse and the formation of diffuse zones of void growth are realistic mechanisms of ductile crack propagation.

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A micromechanical fracture criterion accounting for in-plane and out-of-plane constraint

Cited by 31 publications

References 74 publications

Unified characterisation of in‐plane and out‐of‐plane constraint based on crack‐tip equivalent plastic strain

Unified characterisation of in‐plane and out‐of‐plane constraint based on crack‐tip equivalent plastic strain

Unified correlation of in‐plane and out‐of‐plane constraints with fracture toughness

Ductile crack propagation by plastic collapse of the intervoid ligaments

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