Long-term shock loading of solids by a combined charge with explosive initiation

A method and results of calculation of parameters of long-term shock loading of solids, generated by a gas-dynamic former containing a combined charge with explosive initiation, are described. A calculation model based on the concepts of the hydrodynamic theory of detonation and on the theory of combustion of condensed substances is considered. The forcing pressure and the physical laws of combustion of the combined charge are determined in calculations and experiments. The dynamics of the process is studied by an example of calculation of parameters of the loaded solid acceleration pulse in the case of initiation and combustion of a charge consisting of two batches of high explosives: black powder and pyroxylin powder. The effect of the combined charge parameters and combustion-chamber size on the parameters of the shock loading pulse is studied. __________ Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 50, No. 4, pp. 3–10, July–August, 2009.     

爆炸膨胀环的截面尺寸效应

利用爆炸膨胀环实验数据修正了无氧铜的J-C本构模型参数,计算获得的速度历史与实验测试结 果吻合。通过数值模拟研究了膨胀环宽度对速度历史、应力状态的影响,发现:对厚度1mm 的膨胀环,加载 速度峰值随着膨胀环宽度的增加而增加,当宽度超过8mm 后速度峰值不再变化;膨胀环宽度不超过2mm 时,能较好满足1维应力状态的假定。膨胀环的应力状态在一定范围内具有明显的尺寸效应,可为爆炸膨胀 环的试样尺寸设计提供参考。     

实现材料高应变率拉伸加载的爆炸膨胀环技术

设计了新型的爆炸膨胀环实验加载装置,加载装置中采用爆炸丝线起爆方式,避免了传统装置中对碰爆轰波加载时的应力不均匀性。利用新型的爆炸膨胀环实验技术研究了无氧铜材料的动态性能,利用激光位移干涉仪测量了试样环的径向速度历史,处理数据获得了无氧铜材料的流动应力-塑性应变-应变率的关系,为进一步利用爆炸膨胀环实验技术研究材料在高应变率拉伸加载时的本构关系奠定了基础。     

爆炸加载下金属柱壳破片软回收技术研究

针对爆炸加载下金属柱壳膨胀断裂破片软回收的研究需求,本文通过理论分析和初步的数值模拟设计了由低密度聚氨酯泡沫与水介质为主体的回收装置。与传统单一材料为主的回收装置相比,该回收装置既能在破片高速阶段将低阻抗聚氨酯泡沫对破片的冲击压力减小到约为水对破片冲击压力的1/3,又使破片速度全程持续地较大幅度衰减,还能在破片低速阶段又能充分利用水介质密度大的优势,减小以聚氨酯泡沫单一材料为主的回收装置尺寸。依托该装置开展了炸药加载下304不锈钢柱壳膨胀断裂回收实验。通过测量回收池外壁速度、检查实验后的回收池外观,发现回收池池壁和底部完好,可以重复使用;通过对回收破片称重统计,破片回收率超过85%,破片内外界面辨识度高,破片表面车刀纹清晰可见,内部可见多条未贯穿的裂纹。表明该回收装置对破片的冲击损伤显著降低。根据破片断口和表面信息,推测了破片在金属柱壳的大致位置。本文最后初步给出了回收破片的平均厚度及质量分布等相关信息的统计结果。

     

Numerical simulation of Composition B high explosive charge desensitization in gap test assembly after loading by precursor wave

Results of numerical research into the desensitization of high explosive charges in water gap test-based experimental assemblies are presented. The experimental data are discussed, and the analysis using ANSYS AUTODYN 14.5 is provided. The desensitization phenomenon is well reproduced in numerical simulation using the JWL EOS and the Lee–Tarver kinetic equation for modeling of the initiation of heterogeneous high explosives with as well as without shock front waves. The analysis of the wave processes occurring during the initiation of the acceptor HE charge has been carried out. Peculiarities of the wave processes in the water gap test assemblies, which can influence the results of sensitivity measurement, have been studied. In particular, it has been established that precursor waves in the walls of the gap test assemblies can influence the detonation transmission distance.     

钛合金TC4材料热处理工艺对圆筒在内爆炸载荷下膨胀半径的影响

对采用两种不同热处理工艺的钛合金TC4材料进行了Hopkinson拉伸实验、圆筒爆炸实验和数值仿真,从而确定了两种不同热处理工艺的优劣并通过微观分析揭示了钛合金TC4材料微观组织结构对内爆炸载荷下圆筒膨胀半径的影响.实验和数值分析表明:采用双重退火热处理工艺的钛合金TC4材料具有良好的动态力学性能.在相同的加载条件下,经此工艺处理的TC4圆筒在爆轰产物未泄漏之前有着充分的膨胀半径,而且也不容易形成绝热剪切破坏.同时,给出的依据高速摄影照片确定筒壳断裂点的方法是切实可行的,获得的断裂时间与数值分析结果吻合.     

杆式弹对厚壁壳体装药冲击起爆机制模拟分析

为研究高速杆式弹冲击厚壁壳体装药的起爆机制,运用冲击物理显式欧拉型动力学SPEED软件,开展了不同弹径和弹长的钨合金杆式弹与厚壁壳体Comp-B装药相互作用过程的数值模拟,采用升降法获得弹体起爆装药临界着速及装药起爆位置变化。研究结果表明:弹体起爆装药临界着速随弹径增大而显著降低,随弹长增大呈先降低后平缓变化的规律;弹体以临界着速起爆装药时,存在2种装药起爆机制,即弹体贯穿壳体后的宏观剪切起爆和未贯穿壳体的低速冲击起爆,且其机制随弹体着速在临界着速以上继续提高会发生转变,最终均会转变为高速冲击起爆机制;装药起爆位置均发生在炸药壳体交界面后一定距离处,相同机制下此距离随弹体着速提高而减小。     

A bending quasi-front generated by an instantaneous impulse loading at the edge of a semi-infinite pre-stressed incompressible elastic plate

A refined membrane-like theory is used to describe bending of a semi-infinite pre-stressed incompressible elastic plate subjected to an instantaneous impulse loading at the edge. A far-field solution for the quasi-front is obtained by using the method of matched asymptotic expansions. A leading-order hyperbolic membrane equation is used for an outer problem, whereas a refined (singularly perturbed) membrane equation of an inner problem describes a boundary layer, which smoothes a discontinuity predicted by the outer problem at the wave front. The inner problem is then reduced to one-dimensional by an appropriate choice of inner coordinates, motivated by the wave front geometry. Using the inherent symmetry of the outer problem, a solution for the quasi-front is derived that is valid in a vicinity of the tip of the wave front. Pre-stress is shown to affect geometry and type of the generated quasi-front; in addition to a classical receding quasi-front the pre-stressed plate can support propagation of an advancing quasi-front. Possible responses may even feature both types of quasi-front at the same time, which is illustrated by numerical examples. The case of a so-called narrow quasi-front, associated with a possible degeneration of contribution of singular perturbation terms to the governing equation, is studied qualitatively.