Quasi-brittle fracture during structural impact of AA7075-T651 aluminium plates

Børvik, Tore; Hopperstad, Odd Sture; Pedersen, Ketill Olav

doi:10.1016/j.ijimpeng.2009.11.001

Cited by 162 publications

(84 citation statements)

References 31 publications

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“…AA 7075-T651 was used for the target plates [15][16][17] (Table 1). A toughened epoxy adhesive Betamate 1044 was employed to model the interface between tablets and layers ( Table 2).…”

Section: Problem Descriptionmentioning

confidence: 99%

“…The JC material model has been successfully employed to model ballistic impact on (a) (b) aluminium plates [15,24,[26][27][28][29] and the parameters used in our model are reported in Table 1 and were validated against independent experimental observations of aluminium plates. Materials parameters for JC material model in Table 1 were obtained from [15], while damage parameters for the JC fracture criterion were obtained from [16,17].…”

Section: Validation Of the Jc Materials Model And Materials Parametersmentioning

confidence: 99%

“…Materials parameters for JC material model in Table 1 were obtained from [15], while damage parameters for the JC fracture criterion were obtained from [16,17].…”

Section: Validation Of the Jc Materials Model And Materials Parametersmentioning

confidence: 99%

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Numerical investigation of the impact behaviour of bioinspired nacre-like aluminium composite plates

Flores‐Johnson

Shen

Guiamatsia

et al. 2014

Composites Science and Technology

134

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Inspired by the hierarchical structure of nacre, an aluminium alloy (AA) 7075 based composite featuring layer waviness and cohesive interface is studied as a low weight impact resistant material. To investigate the mechanical response and the ballistic performance of this laminated structure, a numerical study of the proposed nacre-like composite plates made of 1.1-mm thick AA 7075 tablets bonded with toughened epoxy resin was performed using Abaqus/Explicit. Target thicknesses of 5.4-mm, 7.5-mm and 9.6-mm impacted by a rigid hemi-spherical projectile were simulated. The epoxy material was modelled using a user-defined interface cohesive element with compressive strength enhancement. A significant performance improvement was recorded for the 5.4-mm nacre-like plate (compared to the same thickness bulk plate), which was explained by the hierarchical structure facilitating both localized energy absorption (by deformation of the tablet) and more globalized energy absorption (by inter-layered delamination and friction). For a given projectile, however, the performance improvement of using the proposed composite decreased with increasing laminate thickness, which was attributed to the increased likelihood of ductile failure occurring prior to perforation in thicker bulk plates. For 5.4-mm thick plates impacted at high velocity, the nacre-like plate had a better ballistic performance than that of the plates made of continuous (flat and wavy) layers, which was attributed to the larger area of plastic deformation (observed in the nacrelike plate after impact) due to the tablets arrangement.

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“…AA 7075-T651 was used for the target plates [15][16][17] (Table 1). A toughened epoxy adhesive Betamate 1044 was employed to model the interface between tablets and layers ( Table 2).…”

Section: Problem Descriptionmentioning

confidence: 99%

Section: Validation Of the Jc Materials Model And Materials Parametersmentioning

confidence: 99%

See 1 more Smart Citation

Numerical investigation of the impact behaviour of bioinspired nacre-like aluminium composite plates

Flores‐Johnson

Shen

Guiamatsia

et al. 2014

Composites Science and Technology

134

View full text Add to dashboard Cite

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“…Quasi-static tensile tests on smooth and notched axisymmetric specimens and quasi-static shear tests on butterfly specimens have been conducted at ambient temperature (see Børvik et al [9]- [10] and Eriksson et al [11] for specimen geometries). The tensile tests were run at a nominal strain rate of 5·10 -4 s -1 , while the shear tests were run at an average strain rate of 2.5·10 -3 s -1 in the shear zone.…”

Section: Materials and Specimensmentioning

confidence: 99%

“…Figure 1. Tri-planar optical micrograph illustrating the grain structure of the AA7075-T651 alloy and true stress-strain curves to fracture in uniaxial tension for three orientations of the specimen with respect to the rolling direction of the plate [10].…”

Section: Materials and Specimensmentioning

confidence: 99%

On the fracture locus of AA7075-T651

Fourmeau

Benallal

Hopperstad³

2010

EPJ Web of Conferences

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Abstract. The overall goal of this work-in-progress is to try to establish the fracture locus (i.e. the equivalent strain to fracture as a function of the stress triaxiality factor) for the high-strength AA7075-T651 aluminium alloy. Experiments on several specimen geometries enabled us to reach stress triaxialities in the range from ı* = 0 for shear tests to ı* = 1.4 for notched specimen tensile tests. For shear tests, failure occurred by strong strain localization. However, local stresses and strains can not be deduced directly from these tests. Consequently, Digital Image Correlation (DIC) was used to extract the local strain fields to failure. In parallel, numerical simulations of the tests were run using the non-linear finite element code LS-DYNA to extract the evolution of the local stress triaxiality during straining. Based on a combination of both experimental and numerical data, the failure locus of the material can be constructed.

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