有限空腔膨胀理论及约束混凝土抗侵彻机理研究

发布时间：2018-05-20 15:30

本文选题：约束混凝土 + 空腔膨胀　；参考：《国防科学技术大学》2013年硕士论文

【摘要】：本文以新型遮弹结构技术研究为背景,鉴于约束混凝土遮弹层结构的潜在优势和现有研究的严重不足,开展了钢管约束混凝土遮弹层结构单元抗动能弹侵彻探索试验、数值模拟和理论分析,研究了钢管约束混凝土的侵彻机理和抗弹机制,为约束混凝土遮弹技术的深入研究和推广应用提供了依据。本文主要创新性工作和成果如下:(1)改进了现有不可压缩理想弹塑性材料有限球形和柱形空腔膨胀理论。考虑材料压缩性和靶板侧面自由边界径向位移的影响,建立了可压缩理想弹塑性材料有限球形和柱形空腔膨胀理论。数值算例表明:当弹性波未达到自由边界时,本文模型与无限空腔膨胀模型一致;弹性波到达自由边界后,靶体进入弹塑性阶段,自由边界位移影响较小,可以忽略;当塑性区到达自由边界后,边界位移较大,不可忽略。(2)建立了约束混凝土有限球形和柱形空腔膨胀模型,得到了空腔壁压力的理论解。数值算例表明:在膨胀初始阶段,侧向约束的影响较小,随着膨胀过程的发展,侧向约束可显著提高空腔壁压力;当约束刚度较小时,侧向约束作用对空腔壁压力的影响不明显;而当约束刚度较大时,侧向约束使空腔壁压力明显增大;但随着约束刚度的进一步提高,空腔壁压力的提高幅度越来越小,存在合理的约束刚度和靶体半径。(3)进行了钢管混凝土抗12.7mm穿甲弹单发和多发打击试验,得到了破坏模式及主要破坏参数。结果表明:钢管约束混凝土在高速(800m/s以上)侵彻下,迎弹面形成了明显的漏斗坑,核心混凝土侧面形成了环向裂纹,背面混凝土出现了滑移;相对于半无限混凝土,钢管约束混凝土的抗侵彻能力可提高15%以上,且具有较强的抗多发打击能力。(4)侵彻试验、数值模拟和有限空腔膨胀理论相结合,分析了钢管约束混凝土的抗侵彻能力和机理。结果表明:钢管约束混凝土的抗侵彻能力优于半无限混凝土,钢管的约束作用可有效减小混凝土的损伤,提高抗多发打击能力;提高侧向约束刚度可有效提高约束混凝土的抗侵彻能力,合理采用较小的靶体尺寸可提高侧向约束效应,减小混凝土损伤。
[Abstract]:In this paper, based on the research of new type of shielding structure, in view of the potential advantages of confined concrete barrier structure and the serious shortage of existing research, the exploration test of resistance to kinetic energy projectile penetration of steel tube confined concrete shell structure unit is carried out. Numerical simulation and theoretical analysis are carried out to study the penetration mechanism and anti-ballistic mechanism of confined concrete filled steel tube, which provides a basis for further research and application of confined concrete shielding technology. The main innovative work and results in this paper are as follows: (1) the theory of finite spherical and cylindrical cavity expansion of incompressible ideal elastoplastic materials is improved. Considering the influence of material compressibility and radial displacement of free boundary on the side of target plate, the expansion theory of finite spherical and cylindrical cavity of compressible ideal elastoplastic material is established. Numerical examples show that the present model is consistent with the infinite cavity expansion model when the elastic wave does not reach the free boundary, the elastic wave reaches the free boundary, the target enters the elastic-plastic stage, and the free boundary displacement has little effect, which can be neglected. When the plastic zone reaches the free boundary, the boundary displacement is large and can not be ignored. (2) the finite spherical and cylindrical cavity expansion model of confined concrete is established, and the theoretical solution of cavity wall pressure is obtained. Numerical examples show that the influence of lateral constraint is small in the initial stage of expansion. With the development of expansion process, lateral constraint can significantly increase the wall pressure of cavity, and when the constraint stiffness is small, The influence of lateral constraint on cavity wall pressure is not obvious, but when the constraint stiffness is large, the wall pressure increases obviously, but with the further improvement of constraint stiffness, the increase of cavity wall pressure becomes smaller and smaller. The single and multiple impact tests of concrete filled steel tube (CFST) against 12.7mm armour-piercing projectile were carried out with reasonable restraint stiffness and target radius. The failure mode and main failure parameters were obtained. The results show that under the penetration of steel tube confined concrete over 800 m / s at high speed, the projectile surface forms obvious funnel pits, the core concrete forms circumferential cracks on the side, and the back side concrete slips, compared with semi-infinite concrete, The penetration resistance of concrete confined by steel tube can be increased by more than 15%, and it has strong ability to resist multiple attack. The penetration test is carried out. The numerical simulation is combined with the theory of finite cavity expansion, and the ability and mechanism of resisting penetration of confined concrete filled steel tube are analyzed. The results show that the penetrability of steel tube confined concrete is better than that of semi-infinite concrete, and the constraint effect of steel tube can effectively reduce the damage of concrete and improve the ability of resisting multiple strikes. The anti-penetration ability of confined concrete can be effectively improved by increasing lateral restraint stiffness, and the damage of concrete can be reduced by reasonably adopting small target size.
【学位授予单位】：国防科学技术大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU398.9;TJ410

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