计算CHNO和CHNOAl炸药爆速的一种新方法

基于理想混合炸药模型的概念,提出一种计算混合炸药爆速的新方法,并构造空气和铝粉与炸药组分相关的特征爆速关系式。对装药密度大于最大理论密度85%的26种CHNO类混合炸药、13种CNNO类单质炸药、25种含铝炸药进行计算,爆速的计算值与实验值吻合较好,平均相对误差为0.01%,相关系数为0.961 5。通过数据分析,新方法优于Urizar方法和Kamlet方法。新方法是一种计算CHNO类和CHNOAl炸药爆速的可靠方法,对新型混合炸药的研究具有一定指导意义。     

Real-time numerical calculation for penetration depth of projectiles into concrete targets

Based on the acceleration data measured by penetration experiments with ogive-nose projectiles into semi-infinite concrete targets, a fuzzy method which can calculate the real-time penetration depth was developed. In the proposed method, the whole process of penetration was divided into three stages according to the instantaneous velocity, and each stage was described by different models. By judging the calculation error, threshold velocities between stages were automatically determined. Meanwhile, the striking velocity of the penetration process was calculated using the acceleration in whole trajectory. The calculated values by model are in reasonably good agreement with the measured data from experiments.     

半穿甲弹丸对加筋靶板侵彻的终点弹道的实验和理论研究

以舰船典型筋板结构为目标,设计了带加强筋的结构靶,并用模拟实验弹体,对单层带加强筋的结构靶进行了斜侵彻实验,通过天幕靶和高速运动分析系统的测量,得到了两种倾斜着靶条件下不同着靶位置的靶前、靶后弹道参数;通过对靶板破坏结果的分析,得到实验弹靶条件下加强筋结构靶的破坏模式。在现有弹丸侵彻均质靶板理论的基础上和一定假设条件下,得到弹丸对加筋结构靶侵彻的终点弹道理论计算模型,弹丸过靶后剩余速度的理论计算结果与实验结果基本一致。     

提高强冲击荷载作用下平板式防护门门框墙抗力的方法

在强冲击波荷载作用下门框墙转角处会产生明显的应力集中,影响门框墙体系甚至整个防护结构的安全。为解决该问题,提出在迎爆面门框墙和衬砌结合部位设置薄弱层的构造方法,从而减小冲击荷载引起的过大的拉应力。运用考虑了剪切变形的悬臂梁理论分析表明,梁端部约束刚度的变化可以影响结构的破坏形态以及结构的内力分布,降低端部的约束刚度可以有效降低端部区域的内力峰值,延缓结构发生破坏的时间。利用有限元模拟的方法,分析了在出入口门框墙位置设置薄弱层对门框墙动力响应和破坏规律的影响。分析结果表明,设置薄弱层可以有效降低门框墙转角处的应力,降低门框墙结构破坏的风险,进而提高门框墙的抗力水平。     

应力波数值计算中的SPH方法

对一维波动方程的SPH(smoothed particle hydrodynamics)格式和有限差分格式进行比较,并采用SPH法模拟了一维应力/应变波, 获得1个可衡量SPH法模拟应力波准确性的重要指标。结果表明,SPH法模拟应力波传播中采用的光滑长度必须不小于粒子间距;采用B-样条核函数和高斯型核函数能够获得良好的应力波图像,而二次型核函数不能,因此二次型核函数不适用于冲击动力学的数值计算。     

球形装药爆腔预测的准静态模型

炸药土中爆炸形成爆腔的特征尺寸会影响远场地震波的幅频特征。为了准确预测爆腔的特征尺寸,本文建立了爆腔膨胀的准静态模型,该模型给出了无限均匀不可压缩的弹性介质中球形装药爆炸形成的粉碎区、裂隙区半径的解析表达式,并利用该模型计算讨论了不同条件下各分区尺度的变化。最后将该模型与现场实验、动力模型所得到的结果进行对比后表明,该模型与以上两者之间的误差约为5.4%~16.0%,能够较为准确地预测爆腔尺寸。     

Visible light photodegradation of methylene blue by AgBr-TiO2/SiO2@Fe3O4 magnetic photocatalysts

Visible photoactive AgBr/TiO2 was immobilized on a SiO2@Fe3O4 magnetic support by solvother- rnal and sol-gel methods to form a AgBr-TiO2/SiO2@Fe3O4 magnetic photocatalyst. Samples were characterized by X-ray diffraction, high-resolution transmission electron microscopy and magne- tometry. Hereto-structured AgBr/TiO2 was well seeded on the shell-core SiO2@Fe3O4 structure. The AgBr-TiO2/SiO2@Fe3O4 magnetic photocatalyst exhibited high photocatalytic activity in the degrada- tion of methylene blue under visible light. The photocatalyst was superparamagnetic, which is beneficial for facile magnetic separation.     

超高速撞击下钛基复合材料动力学行为研究

 基于已有的铝合金超高速撞击实验研究结果,采用动力分析软件,对铝球撞击铝板进行了数值模拟,验证了数值模拟结果的可靠性,进而对铝防护屏以及与铝防护屏质量相同的钛基复合材料（TMC）防护屏进行了5.52、7.00、和8.00 km/s速度下的超高速撞击模拟,分别对直径为5.02 mm的铝球以及质量等同于铝球的钛基复合材料球做了3种速度下撞击铝屏和钛基复合材料防护屏的数值模拟。通过数值模拟研究可以看出,随着撞击速度的增加,钛基复合材料防护屏的防护效果优于铝防护屏;速度不变,钛基复合材料防护屏防护钛基复合材料球撞击的效果好,铝防护屏防护铝球撞击的效果好。通过超高速撞击模型分析可知,钛基复合材料防护屏的防护效果优于铝防护屏。     

Formation and evolution of vortex rings induced by interactions between shock waves and a low-density bubble

The deformation and instability of a low-density spherical bubble induced by an incident and its reflected shock waves are studied by using the large eddy simulation method. The computational model is firstly validated by experimental results from the literature and is further used to examine the effect of incident shock wave strength on the formations and three-dimensional evolutions of the vortex rings. For the weak shock wave case (Ma?=?1.24), the baroclinic effect induced by the reflected shock wave is the key mechanism for the formation of new vortex rings. The vortex rings not only move due to the self-induced effect and the flow field velocity, but also generate azimuthal instability due to the pressure disturbance. For the strong shock wave case (Ma?=?2.2), a boundary layer is formed adjacent to the end wall owing to the approach of vortex ring, and unsteady separation of the boundary layer near the wall results in the ejection and formation of new vortex rings. These vortex rings interact in the vicinity of the end wall and finally collapse to a complicated vortex structure via azimuthal instability. For both shock wave strength cases, the evolutions of vortex rings due to the instability lead to the formation of the complicated structure dominated by the small-scale streamwise vortices.     

Synthesis,Crystal Structure,Thermal Decomposition and Sensitive Properties of a New Complex [Cu(IMI)4](PA)2

A new coordination complex [Cu(IMI)₄](PA)₂ had been synthesized with imidazole(IMI) as ligands and picrate(PA^-) groups as outer anions, and characterized by Fourier transform infrared(FTIR) spectrum and elemental analysis. Its crystal structure was determined by single crystal X-ray diffraction(XRD) analysis. The crystallographic data show that the crystal belongs to monoclinic, C2/c space group, a=2.542(5) nm, b=0.91773(18) nm, c=1.3778(3) nm, β=107.854(3)° and Z=4. Furthermore, the central copper(II) ion is coordinated by four N atoms from four imi- dazole ligands. All the molecular units are linked into a zigzag pattern along a-axis by the hydrogen bonds, and extended to the distance regularly. Thermal decomposition mechanisms were determined based on differential scanning calorimetry(DSC) and thermogravimetry-differential thermogravimetry(TG-DTG) analysis, and kinetic parameters of the first exothermic process were studied using Kissinger’s and Ozawa-Doyle’s method, respectively. Sensitivity tests show that the title complex has low sensitivity to external stimulus, but it has a higher energy of combustion of 14.2 kJ/g due to which it may be used as the additives of energetic materials to improve the explosive performance.