If balloons are more resistant than the metal walls. Thus, they maintain their structural integrity by causing the material that
constitutes the metal walls of the foam to deform to accommodate the deformations imposed on the sample, which can suffer
the phenomenon of barrel that is characterized by the increase in the cross section of the sample, which gradually it takes the
shape of a barrel if it is cylindrical.
Concerning sandwich panels, another scenario that is still possible is the barreling before it is densified or even significantly
deformed, where the foam layer is more resistant than the solid metal layer.
A short platô which is characterized as strain evolution without a great increase in stress, is observed at the compressive
behavior of the AMSF until 15% of strain before densification began, but a higher amount of energy was absorbed compared
to the solid alloy at the same stress level, as can be seen at the Table 4.2. Considering the same stress W, the AMSF shown
almost ten times more absorption of energy capacity (W) compared to the solid alloy.
Considering that the sample surfaces were prepared with white dots randomly distributed and with a black background,
images were acquired every five seconds during the quasi-static compression test. This allowed for further processing via
GOM Correlate software, as are shown in Fig. 4.3, which quantifies the relative displacement from one point to another,
making it possible to generate deformation mappings. Therefore these mappings made it possible to understand the
macroscopic deformation behavior of the samples, showing through cold colored layers close to the lower surface of the
sample were relatively more deformed than harm colored layers throughout the test, with a greater barreling in these regions
being also observed.
The mechanical properties of aluminum foams are influenced by the matrix material, but also by its cellular structure,
which includes relative density of the composite and pore size. Thus, X-ray computed microtopography presents itself as an
accurate test for the characterization of the cellular structure of metal foams.
The samples were analyzed after being deformed by the compression test, so that the pore densification behavior was better
understood. Figure 4.4a typically represents a top view of a 3.35% deformed sample frame showing 51.54% pore percentage.
Table 4.2 Mechanical properties of the aluminum alloy and the AMSF obtained through compressive tests
Material
Offset stress (MPa)
W (MJ/m
3
)
Stress W (MPa)
Strain W (%)
AlSiMg0.5Mn
137.5
14.41
93.61
1.89
AMSF
40.5
144.09
93.61
15
Fig. 4.2 Stress strain curves of solid alloy AlSiMg0.5Mn and AMSF
22
J. P. Paschoal et al.
constitutes the metal walls of the foam to deform to accommodate the deformations imposed on the sample, which can suffer
the phenomenon of barrel that is characterized by the increase in the cross section of the sample, which gradually it takes the
shape of a barrel if it is cylindrical.
Concerning sandwich panels, another scenario that is still possible is the barreling before it is densified or even significantly
deformed, where the foam layer is more resistant than the solid metal layer.
A short platô which is characterized as strain evolution without a great increase in stress, is observed at the compressive
behavior of the AMSF until 15% of strain before densification began, but a higher amount of energy was absorbed compared
to the solid alloy at the same stress level, as can be seen at the Table 4.2. Considering the same stress W, the AMSF shown
almost ten times more absorption of energy capacity (W) compared to the solid alloy.
Considering that the sample surfaces were prepared with white dots randomly distributed and with a black background,
images were acquired every five seconds during the quasi-static compression test. This allowed for further processing via
GOM Correlate software, as are shown in Fig. 4.3, which quantifies the relative displacement from one point to another,
making it possible to generate deformation mappings. Therefore these mappings made it possible to understand the
macroscopic deformation behavior of the samples, showing through cold colored layers close to the lower surface of the
sample were relatively more deformed than harm colored layers throughout the test, with a greater barreling in these regions
being also observed.
The mechanical properties of aluminum foams are influenced by the matrix material, but also by its cellular structure,
which includes relative density of the composite and pore size. Thus, X-ray computed microtopography presents itself as an
accurate test for the characterization of the cellular structure of metal foams.
The samples were analyzed after being deformed by the compression test, so that the pore densification behavior was better
understood. Figure 4.4a typically represents a top view of a 3.35% deformed sample frame showing 51.54% pore percentage.
Table 4.2 Mechanical properties of the aluminum alloy and the AMSF obtained through compressive tests
Material
Offset stress (MPa)
W (MJ/m
3
)
Stress W (MPa)
Strain W (%)
AlSiMg0.5Mn
137.5
14.41
93.61
1.89
AMSF
40.5
144.09
93.61
15
Fig. 4.2 Stress strain curves of solid alloy AlSiMg0.5Mn and AMSF
22
J. P. Paschoal et al.