cross section crash boxes
cross section crash boxes
cross section crash boxes
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The energy absorption of an Alporas Al foam was shown to increase<br />
approximately 50% at dynamic strain rates (Paul and Ramamurty 2000). The effect of<br />
strain rate on the deformation of Alporas Al foams was further studied by Mukai and his<br />
colleagues (Mukai, et al. 1999, Mukai, et al. 2006). The increase in the aspect ratio of<br />
cell wall thickness to the cell edge length was shown to result in higher cell face<br />
resistance to the cell wall stretching. The strain rate sensitivity of open and closed 6061<br />
Al foams was investigated by Dannemann and Lankford (Dannemann and Lankford<br />
2000). The strain rate dependency of the studied foams was explained by the change of<br />
cell shape at increasing foam densities from polyhedral to spheroidal. Ma and his<br />
colleagues studied the strain rate effect on the crushing behavior of metallic cellular<br />
materials,(Ma, et al. 2009). Voronoi mesoscale model was implemented to resemble<br />
closed cell foam structure in the numerical study (Figure 2.27). Both strain rate<br />
insensitive and sensitive material model were implemented to differentiate the inertial<br />
affects from the strain rate effects. Voronoi and the classical continuum models with<br />
strain rate insensitive material model showed the increases in the crushing stresses at<br />
increasing strain rates, proving the inertial effects on the stress enhancement at high<br />
strain rates.<br />
The energy absorption characteristics of closed cell foam were investigated at<br />
varying impact velocities (Lopatnikov, et al. 2007, Lopatnikov, et al. 2004). The<br />
impact of a rigid plate on a metal foam is considered in four different deformation<br />
regimes. The first regime is the supersonic impact velocities, which is beyond the<br />
virtually all practical applications. In the second regime, the shock compaction occurs,<br />
the elastic wave propagation is neglected. In the third regime, both shock wave and<br />
elastic wave propagation occur. In the fourth regime, the wave propagation is neglected;<br />
the deformation is considered as quasi-static. The energy efficiency in regime 2 depends<br />
on the density of foam and base material, and the mass of the impacted plate. The<br />
energy efficiency in regime 3 depends on the Mach number and the critical stress and<br />
strain of foam.<br />
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