Mixed-mode I/II fracture behaviour of an aluminium alloy

Hallbäck, Nils; Nilsson, Fred

doi:10.1016/0022-5096(94)90001-9

Cited by 84 publications

(49 citation statements)

References 18 publications

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“…The situation is more complicated for mode II loading, but our results agree with the consideration made by Hallbäck & Nilsson (1994) that 'mode II failure results when the direction of the prospective shear band coincides with the crack surface direction, while mode I-type failure occurs when the shear bands are inclined to the direction of crack surfaces'. The detail of the void and its surface is reported; note the unit normal vector, defined to point outward from the elastic body and towards the void.…”

Section: (A ) the Inclined Cracksupporting

confidence: 87%

“…This solution is new in the case when the crack is inclined with respect to the material's orthotropic axes and is fundamental to the understanding of the shear band problem. Although based on the assumption that dead loading tractions are present inside the crack to equilibrate the assumed prestress state, this solution is interesting in itself, when used near the boundary of ellipticity loss, since it reveals features related to the interaction between shear bands and crack tip fields, so that it may explain experimental observations relative to crack growth in ductile materials (McClintock 1971;Hallbäck & Nilsson 1994). 5 The finite-strain J 2 -deformation theory of plasticity has been proposed by Hutchinson & Neale (1979).…”

Section: Introductionmentioning

confidence: 99%

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The unrestrainable growth of a shear band in a prestressed material

Bigoni

Corso

2008

Proc. R. Soc. A.

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A weak line inclusion model in a nonlinear elastic solid is proposed to analytically quantify and investigate, for the first time, the stress state and growth conditions of a finite-length shear band in a ductile prestressed metallic material. The deformation is shown to become highly focused and aligned coaxial to the shear band-a finding that provides justification for the experimentally observed strong tendency towards rectilinear propagation-and the energy release rate to blow up to infinity, for incremental loading occurring when the prestress approaches the elliptic boundary. It is concluded that the propagation becomes 'unrestrainable', a result substantiating the experimental observation that shear bands are the preferential near-failure deformation modes.

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Section: (A ) the Inclined Cracksupporting

confidence: 87%

Section: Introductionmentioning

confidence: 99%

The unrestrainable growth of a shear band in a prestressed material

Bigoni

Corso

2008

Proc. R. Soc. A.

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“…However, only a few studies have examined crack growth behavior of the aluminum alloy under mixed mode loading, especially using compact tension shear (CTS) specimens. When plastic deformation becomes extensive, linear-elastic fracture mechanics cease to be applicable for various fracture parameters (Halbäck et al, 1994;Aoki et al, 1990). According to Knott (1980), the fibrous fracture mechanism can be divided into two extremes of behavior, i.e., micro-void coalescence or fast shear.…”

Section: Introductionmentioning

confidence: 99%

Mixed Mode Fracture Behavior of an Aluminum Alloy A6061 Investigated by using Compact Tension Shear Specimens

Husaini¹,

Zuhaimi²

2016

IJTech

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Aluminum alloys, such as A6061-T6, are widely used in engineering components. However, detailed knowledge is needed to understand the way they respond to a fracture due to mechanical loading. Fractures occur in the structural component from crack propagation, and it is important to understand the mixed mode fracture behavior of crack growth. In this research, mixed mode fracture testing was conducted on the aluminum alloy A6061-T6 by employing a compact tension shear specimen. Crack growth behavior was investigated by applying a quasistatic loading at a constant cross-head speed using a Servopulser universal testing machine. The crack growths were observed by a Keyence digital microscope, and the critical stress intensity factors of the material were examined. Results showed that the shear type of crack initiation preceded the opening-type fracture. , respectively, for the compact tension shear specimen. Crack propagation behavior with three small holes occurring in a zigzag pattern ahead of the crack tip showed that crack initiation and propagation occurred only in the opening-type fracture. The experimental data followed the maximum hoop stress criterion under mode I and mixed mode with a lower mode II component at a loading angle of 75 o . When the small holes occured inline, there were two types of fractures occurring: an opening fracture at crack initiation and then crack propagation caused by shear fracture.

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“…For effects of biaxial loadings on fracture toughness, exper-imental studies have been conducted by researchers (Jones et al 1986;Bass et al 1996;Mostafavi et al 2011) on center-cracked specimens with different biaxiality ratios, defined as the ratio of two perpendicular applied stresses. A literature review revealed that mixed-mode fracture toughness is determined by taking into account the effects of either Mode-II (e.g., Keiichiro and Hitoshi 1992;Kamat and Hirth 1996;Hallbäck 1997) or Mode-III loading (e.g., Manoharan et al 1990;Kamat et al 1994;Liu et al 2004;Paradkar and Kamat 2011) or Modes-II and III loadings (Richard and Kuna 1990;Richard et al 2013) on the total fracture toughness of brittle and ductile materials. parametric studies are conducted to investigate the effect of key parameters on elastic fracture toughness.…”

Section: Introductionmentioning

confidence: 99%

J-Integral Solution for Elastic Fracture Toughness for Plates with Inclined Cracks under Biaxial Loading

Yang

et al. 2018

J. Eng. Mech.

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This version is available at https://strathprints.strath.ac.uk/63936/ Strathprints is designed to allow users to access the research output of the University of Strathclyde. Unless otherwise explicitly stated on the manuscript, Copyright © and Moral Rights for the papers on this site are retained by the individual authors and/or other copyright owners. Please check the manuscript for details of any other licences that may have been applied. You may not engage in further distribution of the material for any profitmaking activities or any commercial gain. You may freely distribute both the url (https://strathprints.strath.ac.uk/) and the content of this paper for research or private study, educational, or not-for-profit purposes without prior permission or charge. Abstract: Surface cracks with different orientations have been recognized as a major cause of potential failures of thin metal structures, which are often under biaxial loading. It has been known that, for cracked ductile metals, plasticity results in an easing of stress intensity at the crack front and ultimately increases the total fracture toughness of the metal. To enable the use of linear elastic fracture mechanics for ductile material failure prediction, the plastic portion of fracture toughness must be excluded. This paper aims to develop a J-integral based method for determining the elastic fracture toughness of ductile metal plates with inclined cracks under biaxial loading. The derived elastic fracture toughness is a function of the plate and crack geometry, strain-hardening coefficient, yield strength, fracture toughness, biaxiality ratio, and inclination angle. It is found that an increase in yield strength or relative crack depth, or a decrease in Mode-I fracture toughness, leads to a larger ratio of elastic fracture toughness to total fracture toughness. It is also found that the effect of biaxiality ratio and inclination angle on elastic fracture toughness is highly dependent on total fracture toughness. It can be concluded that the developed model can accurately predict the fracture failure of ductile thin metal structures with inclined cracks under biaxial loading.Author keywords: Inclined surface cracks; J-integral; Biaxial loading; Elastic fracture toughness; Cracked plates.It has been known that plasticity increases fracture toughness. The underlying mechanism is that yielding caused by plasticity eases stress concentration at the crack front. Consequently, fracture toughness increases and consists of elastic and plastic portions. In order to extract elastic fracture toughness from total fracture toughness, a failure assessment diagram was employed by Yang et al. (2016Yang et al. ( , 2017 and Li et al. (2017). The adopted failure assessment curve (Milne et al. 1988) is independent of both geometry and material properties and may be used for any structure. However, the derived elastic fracture toughness models may be overconservative, given that the curve was derived as a lower bound of the failure assessment diagrams obtained based on...

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Mixed-mode I/II fracture behaviour of an aluminium alloy

Cited by 84 publications

References 18 publications

The unrestrainable growth of a shear band in a prestressed material

The unrestrainable growth of a shear band in a prestressed material

Mixed Mode Fracture Behavior of an Aluminum Alloy A6061 Investigated by using Compact Tension Shear Specimens

J-Integral Solution for Elastic Fracture Toughness for Plates with Inclined Cracks under Biaxial Loading

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