Enhancement of energy absorption in a closed-cell aluminum by the modification of cellular structures

Miyoshi, Tetsuji; Itoh, Masao; Mukai, Toshiji; Kanahashi, H.; Kohzu, H.; Tanabe, Shigenori; Higashi, Kenji

doi:10.1016/s1359-6462(99)00255-9

Cited by 95 publications

(37 citation statements)

References 9 publications

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“…The flow stress of bulk aluminum is dependent on parameters such as level of impurities, grain size, cell size and dislocation density [36][37][38], but nϷ0.26 is consistent with reports in the literature for high-purity bulk aluminum at strains greater than about 3% [39][40][41][42]. Although metallic foams studied in the literature often display a flow curve characterized by a constant flow stress over a wide range of strains (the so-called plateau stress) [1,2,23,31,43,44], strain hardening similar to that observed in this study is also evident in a few prior studies of foams made from relatively ductile metals such as nominally pure aluminum and low-alloyed aluminum [43][44][45][46][47]. The experimental data, thus, agree at low strains with the analysis in Section 4.2 and are consistent with earlier results.…”

Section: Low-strain Plastic Deformationsupporting

confidence: 76%

“…2) represent a volume of material that is "lost" in a structural sense since it carries little or no load. Values of C E lower than predicted by theory are not unusual, and several other studies, both theoretical and experimental, have demonstrated that stiffness strongly depends on the architecture of foams [27][28][29][30][31][32][33][34][35].…”

Section: Elastic Propertiesmentioning

confidence: 69%

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Deformation of open-cell aluminum foam

2001

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Abstract-The mechanical properties of high-purity aluminum foams produced by replication from salt precursors are measured in compression. These foams have homogeneous open-porosity, cell sizes equivalent to the particle size of the precursor salt (ෂ500 µm in this case) and relative densities near 25%. Deformation is uniform and strain hardening similar to the bulk material is observed without a plateau stress. A simple analytical model based on beam theory is employed to describe the flow stress and the change in stiffness of the foams as a consequence of compression. This model leads to a modified scaling law for the flow stress of metallic foams. 

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Section: Low-strain Plastic Deformationsupporting

confidence: 76%

Section: Elastic Propertiesmentioning

confidence: 69%

Deformation of open-cell aluminum foam

2001

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“…Porous aluminum [1][2][3][4][5] possesses several unique properties which can not be achieved by dense materials. High energy absorption, high sound absorption, low density (<1:0 g/cm 3 ) are, for example, typical unique properties of the porous aluminum.…”

Section: Introductionmentioning

confidence: 99%

Observation of Foaming Behavior for Rolled Sheet Precursors Made of Various Aluminum Powders

2011

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One of the practical applications of porous aluminum is the core material for panel/foam sandwich structures. To manufacture the foam/ panel sandwich structure by a powder processing route, a sheet type precursor is essential. Therefore, a foaming behavior of aluminum sheet precursor (pure Al, 6061Al and Al-7Si) was examined. The foaming behavior was examined by the projected area of a precursor recorded by two video cameras from horizontal (lateral-side observation) and vertical (top-surface observation) directions. Average diameters and vertical/ horizontal Feret diameter ratios were used to evaluate pore morphology. Free foaming behavior of the sheet type precursors was extremely unidirectional along the compression direction of the rolled precursor. With regard to pure aluminum and 6061Al precursors, the pore morphology at the early stage of foaming was extremely anisotropic (flat shape), while the pore morphology became spherical when the specimen reached to the maximum expansion. As for the Al-7Si precursors, such flat anisotropic pores were not observed even at the early stage of foaming.

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“…Many researchers attempted to characterize the mechanical properties relating to the geometric structure, e.g., solid distribution, 2) cell face curvature and corrugations, [3][4][5][6] aspect ratio of cell wall thickness against the edge length. 7) Other attempts demonstrated to increase the plateau stress by adding strengthening elements in aluminum matrix. 8,9) These reported results suggest controlling the geometric structure or alloying the aluminum matrix effectively increase the plateau stress and enhancement of energy absorption under a quasistatic loading.…”

Section: Introductionmentioning

confidence: 99%

Energy Absorption in Closed-Cell Al-Zn-Mg-Ca-Ti Foam

2002

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Cellular metallic foams have interesting potential for impact energy absorption. In this study, modification of solid in a closed-cell AlCa-Ti foam was carried out, adding the strengthening elements of Zn and Mg for enhancement of energy absorption. Samples with dimensions of 100 × 100 × 100 mm 3 were examined at a dynamic strain rate corresponding to the crashing speed of automobiles. The compression deformation behavior of the Al-7Zn-0.5Mg-1.5Ca-1.5Ti (by mass%) foam was found to be different from that of the original Al-1.5Ca-1.5Ti (by mass%) foam. Plateau stress could be effectively enhanced with the combined effect of strengthening solid alloy and increasing the aspect ratio of cell wall thickness against cell edge length. Plateau stress of the modified foam was independent of strain rate, while the stress in Al-Ca-Ti foam exhibited a certain strain rate sensitivity. Plateau strain, designated as the strain where the compressive stress reached 1.5 times higher value than the yield stress, was also enhanced by the present modification. As a result, absorption energy was also effectively enhanced but was independent of strain rate as a result of the present modification.

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Enhancement of energy absorption in a closed-cell aluminum by the modification of cellular structures

Cited by 95 publications

References 9 publications

Deformation of open-cell aluminum foam

Deformation of open-cell aluminum foam

Observation of Foaming Behavior for Rolled Sheet Precursors Made of Various Aluminum Powders

Energy Absorption in Closed-Cell Al-Zn-Mg-Ca-Ti Foam

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