Investigation on ignition of an explosive charge in a projectile during penetration based on Visco-SCRAM model
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摘要: 针对弹体侵彻过程中装药的安全性，基于黏弹性统计裂纹力学(visco-statistical crack mechanics, Visco-SCRAM)模型计算装药整体温升、装药裂纹摩擦生热以及弹体装药与壳体摩擦生热，考察这3种机制对装药温升的贡献以及侵彻装药的点火机制，得到了装药点火对应的弹体侵彻临界初始速度。结果表明：(1)装药与弹体内壁摩擦生热对装药温升有一定贡献，随着弹体初始撞击速度的提高，摩擦生热对温升的贡献逐渐增大；(2)黏性、损伤和绝热体积变化导致的装药整体温升对装药点火的作用有限; (3)裂纹摩擦形成热点是侵彻装药点火的物理机制；(4)采用Visco-SCRAM模型可预测低强度、长脉冲载荷作用下的装药点火响应。Abstract: Aimed to the safety of an explosive charge in a projectile during penetration, the visco-statistical crack mechanics (Visco-SCRAM) model was applied to numerically calculate the bulk heat of the explosive charge, the heat produced by the friction between explosive charge cracks, and the heat induced by the friction between the explosive charge and the projectile inner wall. The contribution of the above three mechanisms to the temperature rise of the explosive charge were analyzed, the ignition mechanism of the explosive charge was discussed, and the critical initial penetration velocity of the projectile was obtained corresponding to the ignition of the explosive charge. The investigated results show as follows: (1) the heat induced by the friction between the explosive charge and the projectile inner wall has a certain contribution to the temperature rise of the explosive charge, and this contribution gradually increases as the initial penetration velocity of the projectile increases; (2) the bulk temperature rise produced by the viscosity, damage and adiabatic volume change plays a weak role in the ignition of the explosive charge; (3) the hot spot formation by the friction between the explosive charge cracks is the physical mechanism for the ignition of the explosive charge; (4) the Visco-SCRAM model can be used to predict the ignition responses of explosive charges to low strength and long pulse loads
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Key words:
- mechanics of explosion /
- ignition /
- visco-statistical crack mechanics model /
- penetration charge /
- bulk heat /
- crack /
- hot spot
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图 3 弹体侵彻靶体1/4计算模型
Figure 3. One-fourth of the calculation model for a projectile penetrating a target
图 4 不同初始侵彻速度下装药最高温单元的温度变化曲线
Figure 4. Temperature-time curves of the elements with maximum temperature rise in the charge at different initial penetration velocities
图 5 在基于整体温升模型得到的装药温度分布云图
Figure 5. Temperature contours of the charge based on the bulk temperature rise model at the initial penetration velocity of 430 m/s
图 6 装药单元位置示意图
Figure 6. Schematic diagram of the characteristic explosive elements selected along the axial of the charge
图 7 在弹体初始侵彻速度为440 m/s的情况下，装药不同位置处单元的静水压力变化曲线
Figure 7. Hydrostatic pressure histories of the explosiveelements at different positions in the chargeat the initial penetration velocity of 440 m/s
图 8 在弹体初始侵彻速度为440 m/s的情况下，装药不同位置处单元的最大剪切应变率变化曲线
Figure 8. Maximum shear strain rate histories of the explosive elements at different positions in the chargeat the initial penetration velocity of 440 m/s
图 9 3种不同初始侵彻速度下装药内单元28225热点区域的温度变化曲线
Figure 9. Temperature-time curves in the hot spot of explosive element 28225 in the charge at three different initial penetraion velocities
n G/MPa τ/s 1 944 0 2 173.8 1.366×10-4 3 521.2 1.366×10-5 4 908.5 1.366×10-6 5 687.5 5.000×10-7 
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ν m a/m c0/m vmax/(m·s-1) K0/(Pa·m1/2) 0.3 10 1.00×10-3 3.00×10-5 3.00×102 5.0×105
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