On the effect of relative density on the crushing and energy absorption of open-cell foams under impact

Abstract

a b s t r a c tMicromechanically accurate random foams are used to examine the effect of relative density on the crushing response and energy absorption of aluminum open-cell foams for a range of loading rates. Random soap froth microstructures generated with the Surface Evolver software are dressed with shear deformable beam elements with material distribution that mimics measured values. Foam models of relative densities between 3.67% and 10.0% are crushed first quasi-statically and then dynamically in a direct impact setting covering impact speeds that ranged from sub-to super-critical. Under quasi-static crushing, the limit and plateau stresses and the energy absorbed were found to increase linearly with relative density while the densification strains exhibit a modest linear decrease. In the shock regime, for all densities the proximal stresses rise significantly with relative density whereas the distal ones follow the more modest linear increase of the quasi-static limit stress. The Hugoniot strain depends strongly on impact speed approaching asymptotically values corresponding to the densification of the material at the high end. The energy induced to the material as it crosses the shock also increases also parabolically with impact speed. It was further confirmed that given the shock front velocity-impact speed Hugoniot the rest of the dynamic variables for each foam density can be estimated from the fundamental jump conditions for shocks in solids. For all densities examined it was illustrated that the transition from quasistatic to shock behavior is a process that spans several impact speeds. The transitional range moves to moderately higher velocities as the foam density increases.

Propagation of compaction waves in cellular materials with continuously varying density

“…Recently, experiments on dynamic crushing of aluminium foam (Barnes et al, 2014) and 3D simulations of the compaction of closed metal foam (Zheng et al, 2014) confirmed the validity of the proposed above approach, which is based on the characteristic Hugoniot curves. A more recent study based on the micro-structural analysis of the dynamic uniaxial response of open cell aluminium foam (Gaitanaros and Kyriakides, 2015) confirmed the parabolic character of the Hugoniot strain-velocity dependences used for various material densities. The major advantage of the theoretical methodology based on the Hugoniot strain-velocity relationship is that it allows analysing the primary and reflected waves thus increasing the accuracy of the energy absorption predictions under impact and blast.…”

On the crashworthiness performance of thin-walled energy absorbers: Recent advances and future developments

“…On the other hand, the micromechanical approach considers the microstructure of a real cellular solid. The micro-mechanical models have evolved from simple models with idealised cell geometries and microstructures; such as Kelvin cell models; to more sophisticated random models obtained using the Surface Evolver software [179]. The micromechanical models of foam material can overcome the limitations reported for macromechanical models and can provide more accurate predictions for the crushing behaviour of such materials.…”

Simulation of the Light Transmittance in Macroporous Silica

“…Thanks to their remarkable energy absorption [3][4][5] and vibration damping [6], metallic porous materials can be applied in the automotive industry. Hence over the years, people have paid much attention to the thermal properties [1,[7][8][9][10][11][12] and the mechanical properties [4,5,[13][14][15][16][17][18] of porous materials. Catalyst carrier [19], high-temperature applications [20,21], sandwich panels [22] and porous electrode for fuel cell [19] are also typical examples of porous material applications.…”