cross section crash boxes

Figure 2. 12. Laser assisted foamed Al; (a) side cross-section of laser heating and (b)
foamed Al compacts: Laser: cw CO2. Processing parameters: P = 5kW;
Ar = 30 l/min; Processing speed (V) = (B-a): 2 m/min; (B-b): 0.8 m/min;
(B-c): 0.4 m/min (Source :Kathuria, 2003b)
2.3. Mechanical Behavior of Closed Cell Foams
Under uniaxial compressive loads, metal foams show three distinct deformation
regions in the stress-strain curves: linear elastic, plateau and densification regions as
shown in Figure 2.13(Gibson and Ashby 1997). In linear elastic region, the foam
deformation involves cell edge bending in an open cell foam and cell edge bending
and/or cell face stretching in a closed cell foam. In plateau region, the deformation
proceeds at a nearly constant stress resulting from continuous cell edge/cell wall
collapse/crushing. When all the cells collapse, further deformation presses the opposing
cell walls against each other, resulting in sharp increase in stress values. The region of
sharply increased stress is called densification region.
Deshpande and Fleck (Deshpande and Fleck 2000a) studied the quasi-static and
high strain rate compressive behavior of Alulight (Al-Mg0.6-Si0.3) closed cell and
Duocell (Al6101-T6) open cell foams. The high strain rate tests were performed using a
16