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分析了聚能射流的形成过程,并对其中的各阶段进行了详细建模。在模型中考虑了炸药爆轰、金属的驱动、药型罩压垮以及射流和杵体的形成过程。采用该模型对某一聚能装药结构进行了计算,计算结果表明:药型罩顶部和底部微元的压垮速度较小,在射流头部形成反向速度梯度,与试验数据吻合较好。该模型对于多级侵彻战斗部的工程设计与侵彻参数的计算具有一定的参考价值。 相似文献
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《防务技术》2019,15(4):495-505
Wave shaper effect on formation behavior and penetration performance of reactive liner shaped charge (RLSC) are investigated by experiments and simulations. The reactive materials liner with a density of 2.3 g/cm3 is fabricated by cold pressing at a pressure of 300 MPa and sintering at a temperature of 380 °C. Experiments of the RLSC with and without wave shaper against steel plates are carried out at standoffs of 0.5, 1.0, and 1.5 CD (charge diameter), respectively. The experimental results show that the penetration depths and structural damage effects of steel plates decrease with increasing the standoff, while the penetration depths and the damage effects of RLSC without wave shaper are much greater than that with wave shaper at the same standoff. To understand the unusual experimental results, numerical simulations based on AUTODYN-2D code are conducted to discuss the wave shaper effect, including the propagation behavior of detonation wave, the velocity and temperature distribution of reactive jet, and penetration depth of reactive jet. The simulations indicate that, compared with RLSC without wave shaper, there is a higher temperature produced inside reactive jet with wave shaper. This unusual temperature rise effects are likely to be an important mechanism to cause the initiation delay time of reactive jet to decline, which results in significantly decreasing its penetration performance. 相似文献
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The formation mechanism of an EFP(explosively formed projectile) using a double curvature liner under the overpressure effect generated by a regular oblique reflection was investigated in this paper.Based on the detonation wave propagation theory,the change of the incident angle of the detonation wave collision at different positions and the distribution area of the overpressure on the surface of the liner were calculated.Three-dimensional numerical simulations of the formation process of the EFP with tail as well as the ability to penetrate 45# steel were performed using LS-DYNA software,and the EFP ve-locity,the penetration ability,and the forming were assessed via experiments and x-ray photographs.The experimental results coincides with those of the simulations.Results indicate that the collision of the detonation wave was controlled to be a regular oblique reflection acting on the liner by setting the di-mensions of the unit charge and maintaining the pressure at the collision point region at more than 2.4 times the CJ detonation when the incident angle approached the critical angle.The distance from the liner midline to the boundary of the area within which the pressure ratio of the regular oblique reflection pressure to the CJ detonation pressure was greater than 2.5,2,and 1.5was approximately 0.66 mm,1.32 mm,and 3.3 mm,respectively.It is noted that pressure gradient caused the liner to turn inside out in the middle to form the head of the EFP and close the two tails of the EFP at approximately 120μs.The penetration depth of the EFP into a 45# steel target exceeded 30 mm,and there was radial expansion between the head and tail of the EFE increasing the penetration resistance of the EFP.Therefore,the structural size of the unit charge and the liner can be further optimized to reduce resistance to increase the penetration ability of the EFP. 相似文献
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Strengthening the United States' ability to prevent adversaries from smuggling nuclear materials into the country is a vital and ongoing issue. The prospect of additional countries, such as Iran, obtaining the know‐how and equipment to produce these special nuclear materials in the near future underscores the need for efficient and effective inspection policies at ports and border crossings. In addition, the reduction of defense and homeland security budgets in recent years has made it increasingly important to accomplish the interdiction mission with fewer funds. Addressing these complications, in this article, we present a novel two‐port interdiction model. We propose using prior inspection data as a low‐cost way of increasing overall interdiction performance. We provide insights into two primary questions: first, how should a decision maker at a domestic port use detection data from the foreign port to improve the overall detection capability? Second, what are potential limitations to the usefulness of prior inspection data—is it possible that using prior data actually harms decision making at the domestic port? We find that a boundary curve policy (BCP) that takes into account both foreign and domestic inspection data can provide a significant improvement in detection probability. This BCP also proves to be surprisingly robust, even if adversaries are able to infiltrate shipments during transit. © 2013 Wiley Periodicals, Inc. Naval Research Logistics 60: 433‐448, 2013 相似文献
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As the world becomes increasingly globalized, interruptions to international trade cannot be permitted. Piracy off the coast of Somalia has hampered international trade in the region and poses significant risks to the sailors required to navigate those waters. Over the past three years the global community has attempted, through a number of different naval tactics, to stop these acts of piracy; however, these tactics have proven ineffective. This article looks at historical precedence and military theory to support the concept of using convoys to protect the thousands of cargo vessels traveling round the Horn of Africa every year. This tactic will greatly decrease the number of successful pirate attacks and save countless lives in the process. 相似文献
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基于多信息的柴油机缸套磨损故障诊断研究 总被引:6,自引:2,他引:4
采用了模糊神经网络模型,对柴油机缸套磨损故障以及缸套破坏性磨损故障进行了诊断研究.通过缸套磨损故障的模拟实验,获取柴油机机身振动和铁谱分析等多源多维故障信息,并对融合故障信息进行预处理,解决了模糊神经网络输入矢量的模糊特性化、输出矢量的隶属函数及网络的学习训练问题,对缸套不同磨损故障进行了诊断.研究表明,这种基于多信息的诊断方法减小了故障诊断的不确定性,提高了诊断精度. 相似文献
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基于模糊证据理论的船舶安全评估 总被引:1,自引:0,他引:1
针对船舶安全评估过程中的诸多不确定因素,提出了一种基于模糊证据理论的安全评估方法.将证据体空间中的事件视为模糊子集,并引入模糊概率,更好地描述了专家意见(或知识),给出了质量分配函数的表示.最后,结合某船舶系统,给出了其安全评估的具体实现过程.结果表明,该方法可靠、有效. 相似文献
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We study an infinite‐horizon, N‐stage, serial production/inventory system with two transportation modes between stages: regular shipping and expedited shipping. The optimal inventory policy for this system is a top–down echelon base‐stock policy, which can be computed through minimizing 2N nested convex functions recursively (Lawson and Porteus, Oper Res 48 (2000), 878–893). In this article, we first present some structural properties and comparative statics for the parameters of the optimal inventory policies, we then derive simple, newsvendor‐type lower and upper bounds for the optimal control parameters. These results are used to develop near optimal heuristic solutions for the echelon base‐stock policies. Numerical studies show that the heuristic performs well. © 2009 Wiley Periodicals, Inc. Naval Research Logistics, 2010 相似文献