Uniaxial stress–strain behaviour of aluminium alloy foams

McCullough, K.Y.G.; Fleck, N.A.; Ashby, Michael F.

doi:10.1016/s1359-6454(99)00128-7

Cited by 206 publications

(136 citation statements)

References 10 publications

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“…With increasing plastic strain the number of bands of crushed material increases. At overall macroscopic strains greater than about 40% the whole specimen has crushed and uniform additional straining occurs as discussed by McCullough et al [17]. Table 1.…”

Section: Compression Experiments On Alulight and Duocelmentioning

confidence: 96%

“…This is consistent with the fact that metallic foams are highly heterogeneous imperfect materials with a dispersion strength of the order of 20%. Quasi-static tests show that macroscopic straining occurs by the collapse of spatially random and uncorrelated bands (see for example [16,17]). Thus, it is not expected that a shock wave will propagate along the length of the specimen until the dynamic stress enhancement exceeds the scatter in strength.…”

Section: Shock Wave Propagationmentioning

confidence: 99%

“…8 shows quasi-static ( "10\ s\ ) and dynamic ( +3000s\ ) stress versus strain curves for various densities of Alulight. Recall that the quasi-static plateau stress of Alulight scales with the relative density / to the power 1.5 [17]. A similar scaling law is appropriate for the open-cell Duocel foam, see [29].…”

Section: Compression Experiments On Alulight and Duocelmentioning

confidence: 99%

“…We shall use (10) and (11) to estimate the elevation in strength due to compression of entrapped air. For an Alulight foam of relative density 0.2, we have " "0.4 [17] and "0.2 [8].…”

Section: Ewect Of Compressed Air Pressure In Closed-cell Foamsmentioning

confidence: 99%

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High strain rate compressive behaviour of aluminium alloy foams

Deshpande

Fleck

2000

International Journal of Impact Engineering

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551

266

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The high strain rate compressive behaviour of two cellular aluminium alloys (Alulight and Duocel) has been investigated using the split Hopkinson pressure bar and direct impact tests. It is found that the dynamic behaviour of these foams is very similar to their quasi-static behaviour. The plateau stress is almost insensitive to strain rate, for strain rates up to 5000 s\ . Deformation is localised in weak bands in the Alulight foam but is spatially uniform for the Duocel foam, over the full range of strain rates 10\ s\ ) )5000 s\ .

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Section: Compression Experiments On Alulight and Duocelmentioning

confidence: 96%

Section: Shock Wave Propagationmentioning

confidence: 99%

Section: Compression Experiments On Alulight and Duocelmentioning

confidence: 99%

“…We shall use (10) and (11) to estimate the elevation in strength due to compression of entrapped air. For an Alulight foam of relative density 0.2, we have " "0.4 [17] and "0.2 [8].…”

Section: Ewect Of Compressed Air Pressure In Closed-cell Foamsmentioning

confidence: 99%

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High strain rate compressive behaviour of aluminium alloy foams

Deshpande

Fleck

2000

International Journal of Impact Engineering

Self Cite

551

266

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“…One reason may be that in tension metallic foams tend to have low elongations to failure despite the inherent ductility typical of the metals they are made from. Many commercial aluminum foams are indeed reported to reach their peak stress at strains near 1% or less [5][6][7][8][9], while a few foams elongate, sometimes in specific orientations only, to strains of a few percent [6,7,10,11].…”

Section: Introductionmentioning

confidence: 99%

Uniaxial deformation of open-cell aluminum foam: the role of internal damage

2004

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Internal damage accumulation is measured and shown to play a role in the mechanical response of replicated pure Al and Al12Si open-cell foams. This internal damage is quantified by measuring the reduction in the foamÕs stiffness with strain. The brittle Si second phase fractures during deformation of Al-12Si foam, resulting in damage accumulation rates an order of magnitude greater than for pure Al foam. Elementary damage mechanics is used to relate the measured rate of damage accumulation to the foamÕs tensile failure strain. The analysis and experimental results highlight in particular the strong embrittling influence of brittle second phases within the foam, such as Si.

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The Influence of Cell Shape Anisotropy on the Tensile Behavior of Open Cell Aluminum Foam

et al. 2008

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There are numerous processes for the fabrication of openand closed cell metal foams and some of these methods result in a strong anisotropy in cell shape. The mechanical properties of these specific foams, such as the stiffness, yield stress and ultimate tensile strength (UTS) (see Fig. 1), also show anisotropy which is often linked to the cell shape. [1,2,3,4,5] Gibson and Ashby (G&A) constructed an analytical beam bending model to calculate the influence of the cell aspect ratio, i.e. the long cell axis divided by the short cell axis, on the stiffness and plastic strength. [6] Descriptions based on continuum approaches have been proposed as well. [7,8,9] Obviously, for an experimental validation an accurate experimental determination is important. In fact, X-ray tomography can be used to measure a large number of cells with high precision. [10,11,12] From the measured aspect ratio in the cell shape the anisotropy in the stiffness in tension was calculated in agreement with experiments. [11] In addition, by accounting for the anisotropy in plastic behavior the peak stress and strain have been predicted based on a critical strain criterion. [9] In these studies, however, the role of damage accumulation during straining has not been incorporated in the modeling, nor has it been quantitatively measured as a function of density.In a previous study we have shown that damage accumulation starts well before the peak stress has been reached and that the onset and rate of damage evolution depends critically on the base material properties and the relative density of the foam. [13] The ability of the foam to accommodate the applied strain by strut bending and reorientation was identified as an important mechanism responsible for the large peak strain at small densities. The objective of this paper is to study the effect of cell shape anisotropy looked upon in the light of these mechanisms. We start by relating the yield stress to the cell orientation at small strains, followed by a study of the damage evolution at large strain by measuring the electrical resistance in-situ.The material used is ERG Duocel open cell aluminum foam (20 PPI, alloy AA6101). The relative densities of the samples are grouped according to the following three ranges: 3-5 % (low), 6-7 % (medium) and 10-13 % (high). The relative density of each sample was calculated by measuring the mass and dividing it by the volume and the mass of pure Al (2.7 g/cm 3 ). The samples were received in the annealed (AN) condition (3 hrs at 412°C, followed by slow cooling to 260°C and maintaining that temperature for 0.5 hr followed by slow cooling to RT). Some of the samples were subjected to an additional precipitation hardening heat treatment (HT) to increase the yield stress. First the samples were exposed to a solid solution heat treatment (527°C for 8 hrs) followed by quenching in RT water. After 16 hrs at RT the samples were artificially aged for 8 hrs at 177°C, followed by cooling inside the furnace. Table 1 shows the mechanical properties in tension of the Al a...

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Uniaxial stress–strain behaviour of aluminium alloy foams

Cited by 206 publications

References 10 publications

High strain rate compressive behaviour of aluminium alloy foams

High strain rate compressive behaviour of aluminium alloy foams

Uniaxial deformation of open-cell aluminum foam: the role of internal damage

The Influence of Cell Shape Anisotropy on the Tensile Behavior of Open Cell Aluminum Foam

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