Experimental study on the energy dissipation of foam concrete plate fragmentation under explosion loading

Abstract

Fragmentation is the main energy dissipation form of foam concrete under explosion loading. To characterize the energy dissipation of foam concrete fragmentation quantitatively, explosion loading experiments of foam concrete plates under different stand-offs and plate thicknesses were carried out. The statistical characteristics of fragments and the energy dissipation law of foam concrete plate fragmentation were studied using image processing, fracture mechanics theory and fractal theory. An engineering calculation model of fragmentation fractal dimension and energy dissipation density of foam concrete plates were established. Results show that: the fragmentation of foam concrete plates under different explosion conditions is a fractal in the statistical sense. With the increase in stand-off and plate thickness, the fragment size of foam concrete plates increases, and the fragmentation fractal dimension decreases linearly. The linear relationship between the energy dissipation density and the fragmentation fractal dimension of foam concrete are expressed as 0.0165 1.053 f D ω = +.

Influence Mechanism of Foamed Concrete Coating Thickness on the Blast Resistance of RC Walls

“…On the one hand, under the high-speed impact, foamed concrete will be compacted, and the transmitted stress will rise rapidly; on the other hand, the fragmentation process of foamed concrete will absorb energy and reduce stress [ 8 ]. The thickness of foam concrete mainly affects the attenuation of blast wave and the fragmentation of foamed concrete [ 8 , 10 ]. According to hypothesis (3), after the blast wave passes through the foamed concrete layer, the state point is still on its Hugoniot line.…”

“…When the coating thickness is greater than the lower critical thickness, the damage to the RC wall continues to decrease. However, the coating thickness cannot be increased without a limit, for the energy absorption efficiency will be reduced if it is too thick [ 10 ]. It should be comprehensively considered the blast resistance, economy, and space to select the appropriate coating thickness in the blast resistance design [ 15 ].…”

“…The porous structure of foamed concrete makes it fragile, so the foamed concrete is easy to fracture under blast load. The blasting energy is irreversibly absorbed in the fracture processes [ 10 ]. This is the basis of the blast resistance application of foamed concrete.…”

“…Compared with traditional concrete, foamed concrete formed lighter and low-velocity fragments under blast loading, and the lethality of fragments was greatly reduced. Shang et al [ 10 ] studied the influence of explosion distance and thickness on the fragmentation and energy absorption characteristics of foamed concrete slabs through blast experiments and fractal theory. Wang et al [ 11 ] and Tian et al [ 12 ] analyzed the dynamic response law of foamed concrete steel plate/shell structure under different explosion conditions based on blast experiments.…”

“…This critical length was related to the overpressure of the blast wave and the compressive strength of foamed concrete. Shang et al [ 10 ] analyzed the fragmentation and energy absorption characteristics of foamed concrete cushioning layers with different thicknesses. The results showed that with the increase of the thickness of foamed concrete, the fractal dimension of fragmentation decreased, and the energy absorption efficiency increased first and then decreased.…”