﻿ 高速破片侵彻下防护液舱后板的载荷特性数值分析
 舰船科学技术  2018, Vol. 40 Issue (4): 1-5 PDF

Numerical analysis on load characteristic of guarding liquid cabin′s back plate under high velocity fragment impact
WU Lin-jie, HOU Hai-liang, ZHU Xi
Department of Naval Architecture Engineering, Naval University of Engineering, Wuhan 430033, China
Abstract: Numerical simulations were conducted to research load characteristic of guarding liquid cabin′s back plate under high velocity fragment impact by using LS_DYNA software. The spatial distribution of liquid cabin′s back plate load was analyzed, as well as the effect on liquid cabin′s back plate load of fragment′s velocity and thickness. The fitting formulas for calculating peak pressure and specific impulse at any one point of liquid cabin′s back plate were gained. The research shows that, the load is ultimate at center point of liquid cabin′s back plate which is the projective point of fragment′s center point on the plate, and is exponentially declined when increasing the distance from the center point to the other one point. If fragment′s velocity or thickness increases, the peak pressure and specific impulse at any one point of liquid cabin′s back plate both increase.
Key words: high velocity fragment     guarding liquid cabin     load characteristic     numerical analysis
0 引　言

1 有限元数值计算 1.1 有限元模型

 图 1 有限元模型 Fig. 1 Finite element model
1.2 材料模型及参数

 $p = {C_0} + {C_1}\mu + {C_2}{\mu ^2} + {C_3}{\mu ^3} + ({C_4} + {C_5}\mu + {C_6}{\mu ^2})E\text{。}$ (1)

 $p \!=\! \frac{{{\rho _0}{C^2}\mu \left[ {1 \!+\! \left( {1 \!-\! \frac{{{\gamma _0}}}{2}} \right)\mu \!-\! \frac{\alpha }{2}{\mu ^2}} \right]}}{{{{\left[ {1 \!-\! \left( {{S_1} \!-\! 1} \right)\mu \!-\! {S_2}\frac{{{\mu ^2}}}{{\mu \!+\! 1}} \!-\! {S_3}\frac{{{\mu ^3}}}{{{{\left( {\mu \!+\! 1} \right)}^2}}}} \right]}^2}}} \!+\! \left( {{\gamma _0} \!+\! \alpha \mu } \right)E\text{。}$ (2)

 ${\sigma _d} = \left( {{\sigma _0} + \frac{{E{E_h}{\varepsilon _p}}}{{E - {E_h}}}} \right)\left[ {1 + {{\left( {\frac{{\dot \varepsilon }}{D}} \right)}^{\frac{1}{n}}}} \right]\text{。}$ (3)

1.3 压力测点及计算工况

 图 2 液舱后板的压力测点 Fig. 2 The points on back plate of water cabin for outputting pressure

2 计算结果及分析 2.1 工况1下防护液舱后板的载荷分析

 图 3 工况1下测点A，J～Q的压力曲线 Fig. 3 The pressure curves of points A and J～Q in case 1

 图 4 工况1下各测点的压力峰值 Fig. 4 The peak pressure of different points in case 1

 图 5 工况1下各测点的比冲量 Fig. 5 The specific impulse of different points in case 1
2.2 破片速度和厚度对防护液舱后板载荷的影响

 图 6 K1与v的关系 Fig. 6 The relation of K1 and v

 图 7 K1与δ的关系 Fig. 7 The relation of K1 and δ

 图 8 K2与v的关系 Fig. 8 The relation of K2 and v

 图 9 K2与δ的关系 Fig. 9 The relation of K2 and δ
2.3 防护液舱后板载荷拟合公式及验证

 ${p_{\max }} = 0.006 \cdot {v^{0.9927}} \cdot {\delta ^{0.6714}} \cdot {e^{ - 0.767r}}\text{，}$ (4)
 $i = 4.088 \cdot {v^{0.8847}} \cdot {\delta ^{0.6185}} \cdot {e^{ - 0.641r}}\text{。}$ (5)

v=1 050 m/s，δ=27 mm时，液舱后板上各测点的压力峰值pmax和比冲量i的有限元计算值和式（4）、式（5）计算值分别如图10图11所示，两者吻合较好，从而对式（4）、式（5）进行验证。由式（4）、式（5）可看出，破片的速度v比厚度δ对液舱后板载荷的影响更显著。由于式（4）、式（5）是基于有限元计算结果得出的，并且未考虑液舱的宽度、液舱前后板的厚度及装载水的水位等因素对液舱后板载荷的影响，因此在工程应用上式（4）、式（5）有一定的局限性。尽管如此，对文中的防护液舱结构，当破片的速度v和厚度δ在一定范围内变化时，可以利用式（4）、式（5）对其液舱后板的载荷进行计算。

 图 10 压力峰值（v=1 050 m/s, δ=27 mm） Fig. 10 The peak pressure （v=1 050 m/s, δ=27 mm）

 图 11 比冲量（v=1 050 m/s, δ=27 mm） Fig. 11 The specific impulse （v=1 050 m/s, δ=27 mm）
3 结　语

1）在空间分布上，液舱后板的载荷在板中心（即破片中心在液舱后板上的投影点）最大，随着到中心点的距离增加而呈指数衰减。

2）增加破片的速度或厚度（或者说增加破片的初始动量），将使液舱后板上任一点的压力峰值和比冲量均增大。

3）文中得到的液舱后板上任一点的压力峰值和比冲量的拟合计算公式可以为防护液舱结构的设计提供参考。

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