Energy Absorption And Explosion Proof Ability Of Aluminum Foam

Aluminum foam is a lightweight functional material with porous structure, resulted in the excellent energy absorption and explosion proof ability. Based on the energy absorbing property of aluminum foam, the response of closed-cell aluminum foam and the foam filling material under quasi-static compression and low velocity impact was investigated. The behavior of aluminum foam and sandwich structures with aluminum foam core was also studied under blast loading. At last, the feasibility study was conducted when aluminum foam applied in the heavy equipment buffered platform and the missile launching manhole cover.An axial low velocity impact study has been conducted on three different aluminum foam by drop hammer test setup:6063aluminum foam, pure aluminum foam and cast aluminum201foam. The characteristic curves of aluminum foam with different components were discussed. The differences of deformation modes caused by matrix materials were clear by the analysis of fracture appearance by SEM. With the analysis on profile, three different deformation modes were obtained under different foam density. At last, the energy absorption ability of different samples was studied. The results showed that the characteristic curve and the deformation mode were determined by the properties of matrix metal. When the matrix metal tended to be ductile fracture (pure aluminum foam and6063alloy foam), the displacement-load curve of aluminum foam under dynamic impact contained two steps:initial compression and gradual crushing. The load increased linearly in the first step. In the second step, load increased slightly and oscillated along a horizontal line accompanied with the hardening of curve. When the matrix metal tended to be brittle fracture (cast aluminum201foam), the first step of displacement-load curve was stretched and meanwhile, the oscillation amplitude increased in the second step. A single-track shear deformation band formed during impact. The deformation characteristic was related to the foam density in pure aluminum foam and6063alloy foam."V"-shape deformation mode existed in the foam with foam density ranging from0.186g·cm-3to0.249g·cm-3."I"-shape deformation mode existed in the foam with foam density ranging from0.279g-cm"3to0.436g-cm"3. Deformation was focus on the top and the bottom of aluminum foam with higher density. During impact, the increasing foam density resulted in the higher value of specific energy absorption, which was close related to the matrix material.A quasi-static compression study has been conducted on aluminum tube filling with Al-Ca closed-cell aluminum foam. The deformation process and the energy absorption ability of foam were discussed. Meanwhile, the interaction effect between aluminum foam and metal tube was clear. The results showed that in the compression process, the plastic deformation started at the weak area of aluminum foam. After that, the shear deformation band formed and slipped. Owing to the interaction effect of aluminum foam and tube, the deformation mode of tube was changed and the compaction strain of foam was decreased. The specic energy absorption of foam filled tube was1.3-1.6times higher than the sum of aluminum foam and tube.The higher energy (150-1300J) dynamic impact was conducted on aluminum foam filled tube by drop hammer test setup. Different parameters, containing characteristic curve, deformation mode and energy absorption ability, was discussed. The deformation process of aluminum foam filled tube was clear by profile analysis. The results showed that the filling of aluminum foam shifted the deformation mode of tube from axial symmetry mode to non-axisymmetric mode. It showed that with the increase of foam filling density, some parameters such as Pcr-(the peak load),△FⅠ (the drops of peak load) and (the load volatility in the second step) increased. The mass specific energy absorption of foam filled tube was25-45%higher than that of the foam and meanwhile, the volume specific energy absorption of foam filled tube was90-118%higher than that of the foam. The energy absorption ability of aluminum foam increased significantly after foam filling, whereas, the buffer time decreased.The response of sandwich panels with aluminum foam core was investigated under blast loading. The peak stress of blast wave was tested by PVDF (polyvinylidene fluoride) strain gages. A comparative study on the attenuation ability of mild steel plates and sandwich panels was carried out. It showed that the blast wave decayed linearly with distance in mild steel. With the filling of aluminum foam, the peak load transmitted from the sandwich structure reduced more than95%compared to the peak load incident to the sandwich structure, which is about66%higher than that of mild steel plates. Blast tests performed on the sandwich structure with different aluminum foam core density indicated that the ratio between the peak load incident to the sandwich structure and the peak load transmitted from the sandwich structure decayed exponential as the increase of foam core density. The cell distribution was also be analyzed statistically. It showed that the blast attenuation ability of aluminum foam with lower density and smaller cell diameter will perform better than that with higher density and larger cell diameter. The deformation mechanism of aluminum foam core was also discussed by area sampling analysis. It is clear that the energy was dissipated mainly by the formation and growth of cracks, which is different from the deformation mode of aluminum foam under quasi-static compression and low velocity impact. The blast wave attenuation ability of aluminum foam was tested at last. The results showed that the peak stress of blast wave decayed exponential in aluminum foam.Based on the energy absorption and blast wave attenuation ability of aluminum foam, two types of military equipment were designed and the feasibility study was conducted. Military parachuting cushion platform was made of aluminum foam filled tube. The calculation result showed that the landing kinetic energy of20t equipment can be totally absorbed by aluminum foam and foam filled tube. A missile silos combination of armour plate/aluminum foam/PE fiber plate was designed and was compared with the concrete plate. The resistance of the designed missile silos to ballistic impact was simulated by finite element nonlinear analysis software LS-DYNA. The results showed that the impact resistance capacity of the designed plate with545mm thickness was better than the concrete plate with1500mm thickness. The designed missile silos with aluminum foam performed better than the concrete plate in the resistance of blast wave and ballistic impact.