Research On Mechanics Behavior And Defense Engineering Application Of Void Containing Materials

It is of great value to study the materials with high strength and stress wave clipping effect. In civil defense structures, this kind of material can be used as distribution layer material. Taking civil defense engineering as the research background, this paper prepared a kind of new sialic foamed ceramic material, and created shelly cellular material with excellent triple properties of stress wave clipping effect. First, the parent material of shelly cellular material contains massive hollow cells. Second, the structure of sphere of shelly cellular material is a hollow ball. Third, there is large number of holes among these independent spheres. In this paper, sialic foamed ceramic with porosity of75%is investigated using the method of theoretical analysis, dynamic and static compressive experiments, and numerical simulation to explore its mechanical properties. Then a kind of hollow shelly cellular material made by sialic foamed ceramic is adopted into the underground defense structure to study the attenuation effect on the blast wave. Two kinds of constitutive models are put forward to describe the wave clipping effect of shelly cellular material under blast loading. As a supplement, some research efforts are devoted to the constructive theory of the concrete and penetration resistance of the steel fiber reinforced concrete. The research results have reference value for application and promotion of brittle foamed material in both civil and military fields. Here are the main content of this paper:In order to study the mechanical properties of sialic foamed ceramic composite, Material Test System (MTS) was used to investigate the mechanical behavior of sintering sialic foamed ceramic composite under quasi-static loading. The stress-strain curves, yield strength and the Young’s modulus were obtained over a range of10-5～10-3s-1under uniaxial stress loading. It was found that the behavior of sialic foamed ceramic under uniaxial stress loading exhibited strong strain rate effect, meanwhile a empirical constitutive model could be well fitted to the stress-strain curve. Under uniaxial strain compression, the stress-strain relationship shows obvious strain rate effect and exhibits three phrases:elastic region, plateau region and densified region. The yield strength, yield strain and axial elastic modulus are obtained, meanwhile the poisson ratio is worked out. The energy absorption is also analyzed.Use Split Hopkinson Pressure Bar (SHPB) to investigate the compressive mechanical behavior of a new foamed ceramic composite at high strain rates. The stress-strain curves, yield strength and Young’s modulus are obtained under strain rates of0-100s-1. The experimental technique is improved by adopting rubber dresser, semiconductor strain gauge and large diameter pressure bar. The test results are considered to be able to assure conformability of the tests, validate the stress equilibrium assumption, and show that the stress-strain curves of sialic foamed ceramic composite display strain hardening effect and damage softening effect as brittle materials. Meanwhile the curve includes short plateau region but no densification region.Under the research background of layered defense structure, the similarity rate issue of field explosive tests and the propagation of the stress wave in layered structure are theoretically analyzed. A novel hollow spherical shelly cellular material made by sialic foamed ceramic was used for the stress distribution layer to study the attenuation effect on the blast waves. Field explosion experiments were performed for conventional sand layer and shelly cellular material layer. As far as the distribution layer of shelly cellular material is concerned, the peak stress of the blast wave in support layer was largely reduced due to the extension of pulse width. The comparison of deformations of the projectile shelter layers placed on the shelly cellular material based stress distribution layer and conventional sand distribution layer reveals that the damage of the former is more serious than that of the latter due to more absorption of blast energy. Finally ANSYS/LS-DYNA was used to simulate the dynamic response of the two layered structures under blast loading, proving that the chosen material model could well describe the properties of shelly cellular material in distribution layer.Four constitutive models of concrete are discussed. The strain rate effect of compressive strength of C40concrete is analyzed based on the results of compression experiments under high and low strain rates. Projectile penetrating into concrete was numerical simulated using ANSYS/LS-DYNA. The numerical results of remaining velocity were in good agreement with test results. The results show that the decreasing value of the projectile speed after penetration increases with the incident speed, but the ratio of the decreasing value decreases with the incident speed. The crater formation and damage of the two kinds of target were simulated very well. It’s clearly proved that the JHC model is suitable to simulate such problem as penetration into concrete, and the steel fiber reinforced concrete has stronger penetration resistance than the concrete.