HMX基PBX炸药热损伤的数值计算与实验研究

基于二维平面轴对称模型,采用有限元软件ANSYS,对HMX基PBX在温度冲击载荷作用下的温度场和应力场进行数值计算,为了验证有限元模拟分析的可靠性,对HMX基PBX药柱进行了温度冲击试验,用热电偶和声发射技术测量药柱表面的温度及热损伤。数值计算结果表明,在降温阶段,药柱侧面中部受到较大轴向拉应力作用而产生热损伤。实验结果与计算结果吻合较好,说明HMX基PBX热损伤破坏方式为拉应力破坏,抗拉强度可以较好地反映材料的耐热损伤能力。     

一种含LLM-105的HMX基低感高能PBX炸药

研究了不同颗粒形态的LLM-105对HMX的降感作用以及HMX/LLM-105基炸药配方用的黏结体系和钝感体系.设计出一种HMX/LLM-105配方,采用机械感度和冲击波感度以及板痕试验和圆筒试验对其安全性能和爆轰性能进行了测试.结果表明,LLM-105可作为含能钝感剂用于HMX基PBX炸药,该种含LLM-105的HMX基PBX爆速约8700 m/s、爆压34 GPa以上、比动能为1.560 kJ/g,冲击波感度比JOB-9003炸药低10%,是一种新型的低感高能炸药.     

高品质压装HMX基PBX炸药的冲击波感度

为改善HMX基PBX的安全性能,通过隔板试验研究了高品质HMX的粒度对压装PBX炸药冲击波起爆性能的影响.结果表明·对于相对密度较高(98.5％TMD)的压装HMX基PBX,与普通品质(平均粒径30μm)相比,使用高品质HMX(20 μm)后PBX的冲击波感度下降了7％,当高品质HMX的粒度增至150μm后,其冲击波起...     

核壳型HMX@TATB复合炸药造型粉制备技术研究

核壳型HMX@TATB复合炸药不仅能够显著降低HMX炸药的感度,还能有效保持HMX的高能量密度水平,在未来钝感弹药和安全型高能推进剂领域展现了较好的应用前景,而核壳型HMX@TATB复合炸药基PBX的制备研究对其相关性能测试和后期应用研究起重要作用。本研究探索了核壳型HMX@TATB复合炸药为基PBX造型粉制备过程中的转速、温度和粘结剂的滴加速度等工艺参数对造粒包覆的影响,得到了稳定的百克级核壳型HMX@TATB为基PBX造型粉的造粒工艺。     

含预制缺陷PBX炸药的力学性能及破坏形式

为探索裂纹缺陷对炸药力学性能和破坏形式的影响,以压装HMX基PBX炸药为对象,采用改进后的圆弧巴西试验,研究了不同预制缺陷条件下炸药的破坏过程,并与无缺陷炸药的试验结果进行对比。结果表明,在所研究的范围内,压装PBX炸药的力学强度随缺陷的空间位置变化显著,最高降幅达75.3%;不同缺陷下炸药的破坏形式差异较大,缺陷与加载方向存在夹角时,炸药存在二次承载的现象,且裂纹从缺陷端部向炸药加载面扩展。     

钢模压制下高品质HMX晶体的损伤规律

为了揭示粒度分布与压制期内含能晶体损伤程度的关系,研究了3种不同粒径的高品质HMX炸药在压制后微结构和粒度分布的变化。结果表明,随着HMX晶体粒径的增大,晶体表面逐渐形成裂纹,其尖端和棱角发生破碎。当晶体尺寸达到222.5μm时会出现明显的穿晶断裂。采用两种粒度的HMX级配,可减少对晶体中的损伤。压缩刚度法所得HMX的黏结强度和光电子能谱所得PBX造型粉的包复度表明,随着颗粒粒径的增大,炸药的包覆效果和力学强度降低,导致压制PBX中更多晶体的破碎。     

HMX颗粒特性对压装PBX苏珊感度的影响

采用苏珊试验测试了HMX基压装PBX炸药在低速撞击下的感度,研究了HMX的晶体品质、颗粒尺寸等对PBX撞击感度的影响。结果表明,HMX晶体品质的提高有利于提升PBX的反应阈值速度;在晶体品质相当的情况下,当HMX颗粒由20μm增大到105μm时,PBX的苏珊撞击响应的阈值速度由47m/s升至59m/s,而撞击响应的程度有一定下降。苏珊试验中存在一个临界撞靶速度(约100m/s),低于该速度,含高品质HMX的PBX反应程度小于含普通品质HMX的PBX;高于该速度,含高品质HMX的PBX反应程度则大于含普通品质HMX的PBX。     

PBX炸药细观损伤的实验研究

为研究PBX炸药在冲击作用下的物理损伤、化学损伤及成热的物理机制,采用炸药爆炸驱动隔板实验技术对PBX炸药进行了冲击压缩实验,回收炸药试样并对其不同位置处的断面形貌进行SEM分析.结果表明,随着冲击能量的增加,其温度效应的影响越来越显著,损伤模式从物理损伤向化学损伤过渡.这为XDT问题中的"热点"形成机制等研究提供了实验基础.     

炸药损伤及损伤炸药环境适应性的实验研究

为研究炸药损伤及损伤炸药的安全性,对有边界限定的压装PBX炸药,采用高、低温贮存、温度冲击的方法进行温度损伤实验;采用冲击、振动、跌落的方法进行冲击损伤实验,并利用CT扫描对炸药的损伤情况进行观察;同时通过冲击、振动、跌落实验,对损伤炸药的环境适应性进行了实验研究.结果表明,低温贮存、温度冲击、冲击实验都会使炸药产生裂纹损伤,温度冲击条件下更易引起炸药裂纹损伤.存在裂纹损伤的炸药经过环境适应性实验,未发生爆炸或燃烧现象.     

纳米HMX基PBX的热分解特性

采用溶液-水悬浮法,通过控制水料比、反应温度、搅拌速度等因素制备了纳米HMX基PBX。使用热重(TG)/差示扫描量热(DSC)同步热分析仪研究了其热分解特性。结果表明,纳米HMX基PBX热分解反应的DTG峰温、活化能和放热量分别为557.5K、270.5kJ/mol和816.3J/g;与微米HMX基PBX相比,纳米HMX基PBX的DTG峰温延后3.7K,活化能提高86.9kJ/mol,放热量增加158J/g。在558.3K以下,纳米HMX基PBX的安定性优于微米HMX基PBX。     

JOB-9003炸药"激热"冲击损伤破坏及超声特征

进行了未经热处理的JOB-9003塑料粘结炸药(PBX)标准压缩试样的"激热"冲击损伤破坏试验,对试样热冲击试验前后的超声波特性参量进行了检测,试验显示出JOB-9003炸药存在一个明显的"激热"冲击损伤破坏临界温度差,并获得了试样热冲击损伤破坏的超声波参量特征.     

PBX药柱的不可逆长大对TATB/粘结剂界面粘结性能的影响

研究了热循环对高分子粘结炸药(PBX)药柱的尺寸和力学性能的影响,用扫描电镜观察了断口的形貌.结果表明,PBX药柱在经历反复多次的冷热循环后会出现不可逆的尺寸长大,粘结剂与三氨基三硝基苯(TATB)的界面作用减弱,发生脱粘,材料的抗拉强度也相应下降.     

Time‐Evolution of TATB‐Based Irreversible Thermal Expansion (Ratchet Growth)

TATB is an insensitive high explosive, attractive for use because of its safety aspects. TATB compactions, with or without binder, undergo irreversible volume expansion (or ratchet growth) upon thermal cycling. In the past, experimental elucidation of this phenomenon has focused on irreversible expansion as a function of the number of thermal excursions over a given temperature range, where growth is asymptotic with increasing cycle number. In this paper, we demonstrate that ratchet growth also occurs as a function of time at constant temperature, and that growth is substantial at elevated temperatures. We have measured strain response in PBX 9502, a TATB‐based composite, by performing thermal‐cycling tests with different durations at high temperature. Irreversible growth arises from the thermal ramps themselves (increasing and decreasing), as well as from the subsequent isotherms. PBX 9502 specimens with previously‐identified TATB texture/orientation were used in order to eliminate and/or evaluate texture as a variable. Measurements were also performed on dry‐pressed TATB (no binder) to confirm that expansion as a function of time (constant temperature) is not caused by the binder. A simple analysis of the time‐response data demonstrates consistency in the results. We propose that the primary driving force for irreversible expansion is the proximity of the current strain value (due to thermal history) to the strain saturation point of the current cycle (i.e. strain at infinite high‐temperature hold times or an infinite number of cycles). Such tests should aid in the understanding and modeling of ratchet growth response in these materials.     

压制过程中PBX炸药颗粒的破碎及损伤

用扫描电镜及激光粒度仪研究了PBX炸药在不同压制条件下的微观结构变化及粒度分布。结果表明,随着成型试件密度的增加,晶体的破碎、损伤情况加重;成型试件中HM X的平均粒径随着压力的增加而减小(压制前的33.05μm到250M Pa压制后的16.92μm);在相同压力条件下,热压(70℃)制品的密度更高,但晶体的破碎却更小,热压(70℃)制品中HM X的平均粒径要大于冷压(25℃)制品中HM X的平均粒径。     

Effect of thermal shock cycling on the quasi-static and dynamic flexural properties of flax fabric-epoxy matrix laminates

The aim of the present work is to investigate the influence of thermal shock cycling on the quasi-static and dynamic flexural properties of epoxy matrix composites reinforced with natural flax fibers fabric. Polymer composite laminates reinforced with four plies of natural flax fiber fabric have been manufactured. The samples have been exposed to different number of thermal shock cycles (0, 50, 100, 200, 300, 400), at a temperature range from −40 °C to +28 °C. Dynamic mechanical analysis (DMA) tests were performed on both pristine and thermally shocked specimens in order to determine their viscoelastic response. Due to the thermal shock cycling and after 100 thermal shock cycles, a maximum decrease in storage and loss modulus on the order of 50% was observed. After 100 thermal shock cycles, no further degradation of dynamic properties was observed. On the contrary, damping factor and glass transition temperature values showed a minor variation as number of thermal shock cycles increased. In addition, the time–temperature superposition principle (TTSP) was successfully applied, confirming the fact that the flax fiber fabric-epoxy laminate is a thermo-rheologically simple material. Likewise, quasi-static three-point bending tests were executed and a maximum decrease of 20% in flexural strength was observed after 400 thermal shock cycles. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48529.     

RDX基PBX炸药烤燃试验与数值计算

对RDX基PBX炸药进行了烤燃试验,建立了炸药烤燃计算模型,其中加入了Frank-Kamenetskii、SestakBerggreen和McGuire-Tarver反应模型,采用流体力学计算软件Fluent进行了数值模拟.试验结果表明,PBX炸药在1K/min升温速率下发生剧烈反应的时间为176.0min,此时试样中...     

原位生成堇青石结合红柱石太阳能热发电储热陶瓷的抗热震性能

为提高储热陶瓷材料的抗热震性能,采用原位生成堇青石增强技术,以红柱石为主要原料,通过半干压成型,无压烧结研制了用于太阳能高温热发电红柱石储热陶瓷材料样品。研究了配方组成、烧成温度、相组成、微观结构对样品抗热震性能的影响。结果表明：红柱石添加量为 70%,经1 400 ℃烧成的样品抗热震性能最佳：30 次热震实验（热震条件：1 100 ℃～室温,风冷）的强度不仅没有损失,反而增加了 26.20%。相组成和微观结构分析表明样品的晶相为堇青石、莫来石、硅线石、α-方石英、α-石英等,原位生成的堇青石晶体均匀分布在由红柱石转化的莫来石晶体之间,赋予样品较好的抗热震性能     

Cyclic thermal shock behaviors of carbon fibers reinforced SiCN ceramics with bio-inspired Bouligand-like architectures

Ceramic matrix composites (CMCs) are commonly used for high temperature components in aircrafts. However, thermal shock, as a typical loading case, will cause high thermal stresses in CMCs resulting in brittle fracture failure, and material cracking caused by thermal shock can further reduce the effectiveness of thermal protection function. In the present paper, we propose a bionic hierarchical fiber preform design method to improve the thermal shock resistance of ceramics. The effect of architectures of fiber preforms of continuous carbon fiber-reinforced CMCs on the thermal shock resistance was investigated to understand its importance and the related mechanical mechanisms. Thermal shock (cycling) tests were performed with continuous carbon fibers reinforced SiCN ceramic matrix composites (C_f/SiCN) prepared by PIP. 3D micro-CT scan and three-point bending tests were also conducted to evaluated the resultant damage. The results showed that smaller internal damage and higher thermal shock resistance can be obtained in comparison to pure SiCN ceramics, and the underlying mechanism can be explained by the fact that smaller pitch angle can resist the through-thickness crack propagation via promoting diffused in-plane damage. The present study offers a possibility in developing biomimetic C_f/SiCN ceramics with excellent thermal shock behavior.