基于Hopkinson压杆实验技术的含能材料动态力学性能测试方法研究进展

评述了基于Hopkinson压杆实验技术的高度变率下含能材料动态力学性能测试方法的研究进展.鉴于含能材料的低杨氏模量、密度、波阻,采用Hopkinson压杆测试其力学性能时存在一些问题,如应力平衡、波阻抗匹配等.研究表明,常规的Hopkinson压杆试验装置不能得到准确、可信的试验数据,采用波形整形、压电晶体等方法可以解决应力平衡和波阻抗不匹配等问题.Hopkinson压杆实验技术还能为含能材料在高应变率下本构关系的建立以及损伤模式的分析提供实验结果,并指出了今后含能材料力学性能研究的若干方向.附参考文献44篇.     

冲击载荷下JH-14C传爆药的动态响应实验研究

采用分离式Hopkinson压杆技术对JH-14C传爆药在不同应变率冲击过载作用下的动态响应特性进行研究,观察该传爆药的宏观破坏形式并对回收试样细观损伤模式进行扫描电镜(SEM)观测,获得相应的应力-应变曲线。结果表明,该传爆药的应力-应变曲线呈现明显的应变率效应,失效应力随应变率的增加而增加,失效应变基本保持不变。     

炸药装药在不同应变率响应条件下的安全性研究进展

综述了不同应变率响应条件下炸药装药安全性最新研究进展。通过对炸药装药应用中常用的应变率范围为1~106 s-1的大型落锤实验技术、分离式霍普金森压杆(SHPB)实验技术、一级轻气炮实验技术等进行了评述。分析了不同应变率响应条件下炸药装药安全性实验中存在的问题。根据炸药装药安全性研究的趋势,认为应加强中高应变率响应实验技术的发展,重点完善落锤-霍普金森压杆实验系统的理论及试验体系,提高一级轻气炮实验技术的可控性及重复性。附参考文献61篇。     

RDX基PBX炸药的力学行为和损伤模式

利用电子万能实验机和分离式霍普金森压杆对RDX基PBX炸药进行了实验,获取了不同应变率(10-3～103s-1)下的应力应变曲线,用扫描电子显微镜(SEM)分析了RDX基PBX炸药的微观损伤模式.结果表明,RDX基PBX炸药的力学性能具有明显的应变率效应,失效应力和失效应变均随着应变率的增加而增加.准静态压缩时,试样沿轴线方向开裂,以界面脱粘为主要的损伤模式;而冲击压缩时,试样依然保持原有的块状结构,界面脱粘和晶粒破碎两种损伤模式并存.     

环氧树脂/蒙脱土纳米复合材料的动态力学性能研究

利用分离式Hopkinson压杆研究了环氧树脂/蒙脱土纳米复合材料在102～104/s高应变率范围下的动态力学性能.用三点弯曲试样的动态响应得到动态强度因子曲线,由曲线及裂纹起裂时间求出了不同蒙脱土含量试样动态断裂韧度.     

溶剂浸渍树脂吸着螺旋霉素的动力学模型研究

本文根据颗粒扩散控制机制,认为溶剂萃取过程和固体内表面的吸附同时发生,建立了有限浴条件下溶剂浸溃树脂吸着螺旋霉素的动力学模型.浸渍树脂静态吸附螺旋霉素的计算值与实验值接近,得到螺旋霉素在浸渍树脂内的有效扩散系数为3.7×10~(-12)～29.4×10~(-12)m~2/s.线性吸附等温线条件下的分析解与非线性条件下的数值解比较,表明线性假设能较好地反映实际过程.     

溶剂浸渍树脂吸着螺旋霉素的动力学模型研究

本文根据颗粒扩散控制机制,认为溶剂萃取过程和固体内表面的吸附同时发生,建立了有限浴条件下溶剂浸溃树脂吸着螺旋霉素的动力学模型.浸渍树脂静态吸附螺旋霉素的计算值与实验值接近,得到螺旋霉素在浸渍树脂内的有效扩散系数为3.7×10~(-12)～29.4×10~(-12)m~2/s.线性吸附等温线条件下的分析解与非线性条件下的数值解比较,表明线性假设能较好地反映实际过程.     

冲击载荷下2-2型水泥基压电复合材料力电响应特性

研究2-2型水泥基压电复合材料在冲击载荷下的力电响应特征,利用分离式Hopkinson压杆装置进行冲击加载,借助超高速摄影技术观察试样在冲击载荷下的破坏形貌。结果表明:冲击载荷下,压电复合材料具有明显的应变率效应,是应变率敏感材料;压电复合材料的力电响应存在一个临界值,当应力小于该临界值时,试样的电信号与施加载荷之间具有良好的线性关系;动态增强因子可以有效描述压电复合材料压缩强度的率效应规律,在线性范围内,随着应变率的增大,试样的动态增强因子也增大,且具有稳定的增长率;由Maxwell模型得到的压电复合材料应力松弛时间随应变率增大单调递减;冲击载荷下,2-2型水泥基压电复合材料与压电陶瓷的电学失效发生在力学失效之前,且均呈现“爆炸式”破碎,压电陶瓷还伴随着明显的电弧放电现象。     

采用压力脉动信号分析法对三相流化床流型划分的研究

本文采用床层压力脉动信号的计算机在线分析方法进行了并流三相流化床流型转变过程的研究.为了查明操作条件(气速、液速)和颗粒物性(密度、粒径)对转变过程的影响,进行了一系列的实验工作.最后得到在空气-水-颗粒的三相流化体系内,从气泡合并区向气泡分散区转变的判别式:在R_(eg)p_(?)/p_l·(D_T/d_p)~(-1.589)·Fr_g~(-0.1)≥1.01×10~5条件下如果Re_(lc)(U_(mf)~(?)/U_(mf)~())~(0.388)·Re_U_(mf)~(?)~(-0.461)·((p_(?)-p_l)/p_l)~(-0.478)≥13.4则流化床处于分散区操作,反之,则处于合并区操作状态.     

硫酸镁一步法制备氢氧化镁阻燃剂

实验确定了由硫酸镁一步法制备阻燃型氢氧化镁较适宜的条件为：表面处理剂添加量5~10 mL(以制备5 g氢氧化镁为基准),恒温处理时间3~4 h,陈化时间4~6 h. 此工艺条件下,所制得的氢氧化镁样品XRD分析表明,(001)面对应的衍射峰强度明显高于(101)面,样品(101)方位的扭歪值h<3.0′10-3,比表面积SDET<20 m2/g,颗粒形貌为棒状,直径为25~50 nm,长径比为8~10,且分散性好,样品符合阻燃型氢氧化镁的特殊要求. 该工艺具有流程短、设备简单、操作条件温和(常压、低温操作)、成本低等特点.     

Critical Appraisal of Limiting Strain Rates for Compression Testing of Ceramics in a Split Hopkinson Pressure Bar

The split Hopkinson pressure bar (SHPB) is being widely used to determine the dynamic compressive strength of ceramics and ceramic composites. However, extreme caution needs to be exercised while testing these highstrength ceramics at high strain rates. The highest strain rate at which ceramics can be tested using an SHPB without violating the underlying assumptions is found to be in the range of 2500–3000/s. It is also shown that at very high loading rates, dispersion in the transmitted pulse can lead to discrepancies in measuring the dynamic failure strength of ceramics.     

Testing of High-Strength Ceramics with the Split Hopkinson Pressure Bar

The split Hopkinson pressure bar was used to study the failure of a high-strength alumina at strain rates on the order of 10³ s^-1. There appears to be a critical strain rate above which the traditional method of using the transmitter bar signal to calculate the stress in the specimen is no longer valid. To compute the correct stress in the specimen it was necessary to use the strain signal from a gage mounted directly on the specimen.     

玻纤/环氧三维编织复合材料的动态压缩性能

本文利用SHPB（the split Hopkinson pressure bar）装置对玻璃纤维／环氧三维编织复合材料在高应变率（4000s^-1，5000s^-1，6000s^-1）下的动态压缩性质进行测试，试验结果表明玻纤／环氧三维编织复合材料是应变率敏感材料。     

Response of an HMX based explosive to dynamic loading by the Hopkinson split bar technique

The dynamic compression and localized adiabatic shear in samples of an HMX based explosive was studied using the split Hopkinson bar technique. Dynamic compression tests were performed at strain rates of (0.3–2.0) · 10³ s^?1. Fracture of the explosive samples was found to occur at stresses of 60–80 MPa. The behavior of HMX based samples was also studied in localized shear tests at different strain rates (200–2500 s^?1). The initiation of explosive transformations under the dynamic loads is discussed.     

Quasi-static and dynamic compressive fracture behavior of carbon/carbon composites

To understand the dynamic compressive fracture behavior of carbon/carbon composites, their compressive behavior was investigated at a strain rate of 500/s using a modified split Hopkinson pressure bar. Quasi-static compressive tests were conducted on a universal test machine and compared with those at high strain rate. Scanning electron microscopy was used to observe the compressive fracture surfaces. The results show that the compressive strength and stiffness are increased at high strain rate. Fiber failure under quasi-static compressive loading is characterized by fiber bundle debonding, breakage and pull-out, while the fiber failure under dynamic compressive loading is characterized by multiple splitting without extensive debonding.     

Mechanical behavior of ceramic-metal joint under quasi-static and dynamic four point bending: Microstructures,damage and mechanisms

This paper studies the mechanical behavior of Alumina ceramic-Kovar joint under quasi-static and dynamic four-point bending (FPB). The joint is fabricated by molybdenum-manganese (Mo-Mn) metallization method with extra additions. The bend strength of the joint is improved by glass phase migration. Electronic universal testing machine and modified split Hopkinson pressure bar (SHPB) are employed to realize the loading process. The microstructure of the joint is investigated by scanning electron microscope (SEM) and the chemical composition is determined by energy dispersive spectrometer (EDS). Digital image correlation (DIC) technique is used to determine the displacement contours and ultra-high speed camera is used to monitor the deformation and crack evolution around the joint. It is found that the specimen will slip due to the different Young's modulus of base material. The dynamic bend strength of the joint is lower than the quasi-static bend strength. The failure mechanism of the ceramic-metal joint is mainly intergranular failure for the dynamic bend but mixed transgranular/intergranular failure for the quasi-static case. The crack starts from the inherent voids inside the ceramic and then expands along the metallization band between solder and ceramic.     

多轴向经编针织(MWK)复合材料SHPB动态响应

利用霍普金森杆（sHPB）横向冲击多轴向经编针织复合材料，在不同子弹冲击速度下测试材料动态响应，通过计算得出载荷与时间的关系曲线；实验表明：材料的抗分层性能出众；在准静态三点弯曲载荷下，试样破坏模式为典型的弯曲破坏；在SHPB冲击载荷下，试样破坏模式以基体开裂、纤维与基体界面破坏和纤维断裂抽拔为主。     

低温下泡沫混凝土的动态力学性能

为了研究低温下泡沫混凝土的动态力学性能,采用φ100 mm的铝制分离式霍普金森压杆(SHPB)装置对不同温度下泡沫混凝土试件进行冲击压缩试验,得到了不同温度、应变率下的泡沫混凝土的应力应变曲线、能量参数、破碎形态等。结果表明:当应变率在62.59 s^-1以下时,泡沫混凝土应力应变曲线分为线弹性阶段、屈服阶段、破坏阶段;当应变率超过62.59 s^-1时,其应力应变曲线分为线弹性阶段、屈服阶段、局部失稳、应力平台、破坏阶段;常温、0 ℃、-10 ℃、-20 ℃和-30 ℃下,泡沫混凝土的动态抗压强度以及吸收能在对应的应变率分界点前表现出显著的应变率效应,但超出该分界点后,应变率效应便不再明显;泡沫混凝土的动态峰值抗压强度与吸收能随温度的降低而提高,但峰值应变随温度降低而降低;泡沫混凝土冲击破碎后的块度随着温度的降低逐渐变大。在低温环境下泡沫混凝土的抗动载设计中,对于泡沫混凝土的峰值抗压强度、吸收能,应优先考虑温度效应的影响,而对于其峰值应变,应优先考虑应变率效应。     

摩擦效应对某PBX炸药动态力学性能的影响

基于分离式霍普金森压杆(SHPB)围压加载下的试样受力模型,考虑试样与套筒间的摩擦效应,建立了动态力学性能参量(动态泊松比及动态杨氏模量)的修正方法,并以某浇注PBX炸药为例,分别以常规方法和修正方法计算了4种试样的动态力学性能,并进行了对比。结果表明,对于实验所用的浇注PBX炸药,在应变率300~2000s~(-1)内,修正方法与常规方法所获得的动态参量误差不超过5%,可以忽略摩擦效应对此PBX炸药动态参量的影响。