cross section crash boxes

Similar to uniaxial compression of Al foam, pressure vs. volumetric strain
response of hydrostatic compression shows three distinct regimes; linear elastic,
hardening plastic and densification. The strain hardening in hydrostatic compression is
however higher than that in uniaxial compression as depicted in Figure 2.15,
The specimen size effects on the mechanical behavior of Alporas closed cell and
Duocell open cell Al foams were determined by Andrews et al. (Andrews, et al. 2001,
Onck, et al. 2001) . It was reported that Young's modulus and plastic collapse strength
of both foams increased with increasing the ratio of specimen size to cell size, L/d. It
was also detected that the decrease in Young's modulus and strength values with
decreasing the ratio of specimen size to cell size in open cell foams was more rapid than
in closed cell foams, mainly due to the lack of cell faces in open cell foam. The size
effect on the shear strength was found to disappear for the specimens with a thickness at
last twice the cell size as shown in Figure 2.16.
Figure 2. 15. .The uniaxial and hydrostatic stress-strain curves of Alulight foams.
(Source: Shridhar and Fleck 2005)
20