Effect of displacement-rate on the indentation behavior of an aluminum foam

Kumar, Praveen; Ramachandra, Srinivas Sulugodu; Ramamurty, Upadrasta

doi:10.1016/s0921-5093(02)00608-1

Cited by 48 publications

(32 citation statements)

References 13 publications

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“…During indentation, low density foam deformation underneath the indenter has been shown to be mostly plastic, and thus mostly compressible; areas outside the indentation area have been shown to remain undeformed, which is consistent with a fully compressible material [17,26,28,32,33].…”

Section: Nanoindentation Technique Validationmentioning

confidence: 73%

“…All samples were indented to depths ranging from 100 nm to 2 µm; note that even the deepest indents correspond to less than one percent of the total sample thickness (250-300 µm). In the case of densification effects, it has been shown that, during indentation, the area underneath the indenter is compressed and [26,28,32].…”

Section: Nanoindentation Technique Validationmentioning

confidence: 99%

See 1 more Smart Citation

Scaling equation for yield strength of nanoporous open-cell foams

et al. 2007

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A comprehensive study on the relationship between yield strength, relative density and ligament sizes is presented for nanoporous Au foams. Depth-sensing nanoindentation tests were performed on nanoporous foams ranging from 20 to 42% relative density with ligament sizes ranging from 10 to 900 nm. The Gibson and Ashby yield strength equation for open-cell macro-cellular foams is modified in order to incorporate ligament size effects. This study demonstrates that at the nanoscale, foam strength is governed by ligament size, in addition to relative density. Furthermore, we present the ligament length scale as a new parameter to tailor foam properties and achieve high strength at low densities.

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Section: Nanoindentation Technique Validationmentioning

confidence: 73%

Section: Nanoindentation Technique Validationmentioning

confidence: 99%

Scaling equation for yield strength of nanoporous open-cell foams

et al. 2007

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“…When this material is frequently used in blast-protected devices [2], indentation becomes a potential mode of failure. Ramachandra et al [3,4] experimentally investigated the indentation behaviour of an aluminium foam under dynamic loads. In their research, drop-tower experiments were used to investigate the energy-absorption ability of aluminium foams under a velocity of 3∼30 m/s.…”

Section: Introductionmentioning

confidence: 99%

Indentation of aluminium foam at low velocity

Shi

Miao

Liu

et al. 2015

EPJ Web of Conferences

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Abstract. The indentation behaviour of aluminium foams at low velocity (10 m/s ∼ 30 m/s) was investigated both in experiments and numerical simulation in this paper. A flat-ended indenter was used and the force-displacement history was recorded. The Split Hopkinson Pressure bar was used to obtain the indentation velocity and forces in the dynamic experiments. Because of the low strength of the aluminium foam, PMMA bar was used, and the experimental data were corrected using Bacon's method. The energy absorption characteristics varying with impact velocity were then obtained. It was found that the energy absorption ability of aluminium foam gradually increases in the quasi-static regime and shows a significant increase at ∼10 m/s velocity. Numerical simulation was also conducted to investigate this process. A 3D Voronoi model was used and models with different relative densities were investigated as well as those with different failure strain. The indentation energy increases with both the relative density and failure strain. The analysis of the FE model implies that the significant change in energy absorption ability of aluminium foam in indentation at ∼10 m/s velocity may be caused by plastic wave effect.

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“…46 The characteristics of flat-punch indentations into VACNT films closely resemble those reported for metallic 40,47 and polymeric foams. 41,46 In the spirit of foam-like deformation, the indentation zone for VACNTs is confined to the region directly beneath the indenter, while the surrounding regions are unaffected (see Fig.…”

Section: F Comparing Indentation and Compressionmentioning

confidence: 55%

“…2(c) and 2(d)] are unique characteristics seen only in the intertwined VACNT systems. Neither foams, 40,41 where the deformation is confined only to regions directly beneath the indenter, nor noninteracting VACNTs, 42 where such shear would propagate without any microroller formation, show the unique features seen in Fig. 2.…”

Section: Resultsmentioning

confidence: 99%

Compressive response of vertically aligned carbon nanotube films gleaned from in situ flat-punch indentations

et al. 2012

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We report the mechanical behavior of vertically aligned carbon nanotube films, grown on Si substrates using atmospheric pressure chemical vapor deposition, subjected to in situ large displacement (up to 70 lm) flat-punch indentations. We observed three distinct regimes in their indentation stress-strain curves: (i) a short elastic regime, followed by (ii) a sudden instability, which resulted in a substantial rapid displacement burst manifested by an instantaneous vertical shearing of the material directly underneath the indenter tip by as much as 30 lm, and (iii) a positively sloped plateau for displacements between 10 and 70 lm. In situ nanomechanical indentation experiments revealed that the shear strain was accommodated by an array of coiled carbon nanotube "microrollers," providing a low-friction path for the vertical displacement. Mechanical response and concurrent deformation morphologies are discussed in the foam-like deformation framework with a particular emphasis on boundary conditions.

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Effect of displacement-rate on the indentation behavior of an aluminum foam

Cited by 48 publications

References 13 publications

Scaling equation for yield strength of nanoporous open-cell foams

Scaling equation for yield strength of nanoporous open-cell foams

Indentation of aluminium foam at low velocity

Compressive response of vertically aligned carbon nanotube films gleaned from in situ flat-punch indentations

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