2A12铝合金本构关系和失效模型

通过万能材料试验机、扭转试验机、霍普金森拉杆和Taylor 撞击实验研究高强铝合金 2A12 在常温至250 益的准静态、动态本构关系和失效模型。基于实验结果,修改了Johnson-Cook 强度模型中的应变强化项以及Johnson-Cook 失效模型中的温度软化项,并结合数值仿真得到了模 型参数。实验结果表明,2A12 铝合金的应变强化效应和温度软化效应显著,而应变率硬化效应不 显著;失效应变随温度的增加、应力三轴度的减小和应变率的增加而增加。     

低温下聚碳酸酯冲击拉伸性能的实验研究

为了研究聚碳酸酯在低温条件下的力学行为,在冲击拉伸试验装置上对聚碳酸酯板进行了不同环境温度下的高应变率单向拉伸实验,获得了-60℃、-20℃和室温下应变率为360 s-1、800 s-1和1 700 s-1的拉伸应力应变曲线。试验结果表明,在实施的温度范围内,随着温度的升高,聚碳酸酯的屈服应力和失稳应变都有不同程度的减小;在同一实验温度下,随着应变率的增加,屈服应力和失稳应变均增大,呈现高速韧性的特征。     

温度和应变率历史对拉伸载荷下铁基记忆合金本构关系影响的研究

在20～500℃和0.00208～193s-1的范围内研究了温度和应变率历史对拉伸载荷下铁基记忆合金本构关系的影响.实验结果表明,应变率历史对该材料具有强化作用,而且随着预应变率的提高,其强度提高,延伸率降低.其对应变率历史的敏感性则随着温度的升高而降低.     

复合泡沫塑料准静态压缩的应变率效应和温度效应

针对不同密度、不同空心玻璃微珠填充比的聚氨酯复合泡沫塑料进行了准静态压缩实验,研究了这类材料在不同应变率和不同温度下的宏观力学性能.结果表明,在不同应变率和不同温度下复合泡沫塑料的模量和强度是不同的,具有明显的应变率效应和温度效应.并且,在所研究的温度范围内(从室温到玻璃化转变温度),模量随温度的变化关系是非线性的,可用分段直线来描述;而强度与温度之间基本上保持线性关系.此外,在已有的宏细观力学实验基础上,进一步分析了空心玻璃微珠对复合泡沫塑料的增强机理.     

炮钢材料动态本构模型及其验证

在温度88~573 K和应变率0.001~2 000 s^-1的条件下,通过温度与应变率耦合的静态和动态分离式Hopkinson压杆实验,并以初步获得的炮钢材料动态本构模型基本参数为基础,通过进一步的优化及Taylor杆冲击实验,验证并最终确认了炮钢材料动态本构模型参数,模型预测与实验结果相对误差小于5%. 验证结果表明,建立的炮钢材料动态本构模型能真实地反映其动态响应。     

真空退火态钨合金的动态力学性态及其本构关系

借助于SHPB实验技术,对真空退火态93W材料在应变速率低于5000s~(-1)范围内的动态力学性态进行了实验研究。发现该材料对应变率具有明显可察觉的敏感性,其动态屈服限在所考察的应变率范围内提高了近一倍。温度从—50℃提高到200℃时,动态屈服限(ε=1100s~(1-))降低了约30％。基于塑性变形的位错动力学分析,建立了考虑应变率和温度效应及双相合金特点的动态本构关系,并对其应用可靠性进行了模拟计算分析。     

宽温域宽应变率下丁羟四组元HTPB推进剂单轴压缩力学行为

为研究丁羟四组元端羟基聚丁二烯（HTPB）推进剂在宽温域宽应变率下的单轴压缩力学行为,基于万能材料试验机、高速液压伺服试验机、分离式霍普金森压杆,结合可程式恒温恒湿试验机等温控手段,开展了宽温域宽应变率下的推进剂单轴压缩力学性能实验,获取了-40,-25,-10,20,50 ℃ 5个温度下10^-4~10³ s^-1应变率的丁羟四组元HTPB推进剂的应力应变曲线,并建立了HTPB推进剂的分段式单轴压缩率温本构关系。结果表明,HTPB推进剂的力学响应存在显著的率温相关性,在任意应变率下其力学响应都呈阶段性变化,即线弹性阶段-非线性屈服阶段-应变软化阶段或应变硬化阶段;且在高应变率下,非线性屈服行为后的应变软化现象明显弱于低、中应变率。此外,高应变率时,随着温度的降低,应力应变曲线的变化速率逐渐减缓;而低、中应变率却恰恰相反,随着温度的降低,应力应变曲线的变化速率逐渐加快。HTPB推进剂的力学强度随着温度的降低显著增大,温度从50 ℃降低至-40 ℃时,HTPB推进剂试件在宽应变率作用下的最大应力从2.2~8.8 MPa增长至约11~22 MPa。同时基于实验数据构建了分段式率温本构关系,发现其在温度较高时拟合效果更好,能够较好地预测HTPB推进剂的力学行为。     

7A52铝合金Johnson-Cook本构模型的有限元模拟

为探究7A52铝合金的流动应力变化规律,在材料拉伸试验数据基础上,建立Johnson-Cook本构模型。利用有限元软件AQAQUS,模拟7A52铝合金在温度为25~400℃、应变率为0.1~10 000 s~(-1)的准静态和动态拉伸试验。结果表明:温度和应变率都会影响7A52铝合金的流动应力,但对温度的敏感性较大,对应变率敏感性较小;流动应力随着温度的升高而减小;流动应力随着应变率的增加而增大,尤其在应变率高于1 000 s~(-1)时影响更加明显。所建有限元模型结果与试验结果吻合较好,证明该Johnson-Cook本构模型能够在一定温度和应变率范围内预测7A52铝合金的流动应力。     

一维应力动态加载下战斗部装药力学响应预报模型

为获得战斗部装药在高过载侵彻下的动力学行为,对战斗部装药（黑索今(RDX)基高聚物粘结炸药(PBX)）在高应变率下的动态力学响应特性进行了研究。采用改进的分离式霍普金森压杆(SHPB) 实验技术对RDX基PBX炸药动态力学性能展开研究、压电传感器监测试件两端应力状态、高速相机拍摄实验中的试件变形过程,确保实验试件变形在动态应力平衡和常应变率加载条件下进行,保证实验数据的有效性。结果表明,该RDX基PBX炸药具有明显的密度效应及应变率效应,当应变超越0.075时应变率效应显著增强。基于应变能函数,建立该RDX基PBX炸药在一维应力状态下修正的Rivilin本构模型,模型拟合结果与实验结果基本相符,仿真结果得到的应变时间信号及试件变形模式与实验结果基本吻合。     

高温-高应变率下MB2合金的动态力学性能及变形机理

利用分离式Hopkinson杆实验加载装置,结合入射波整形技术,进行MB2合金不同初始温度、不同温度、不同应变率下冲击压缩实验。并利用获得的应力-应变数据,采用修正的Johnson-Cook本构模型,拟合MB2合金的本构关系。同时,利用金相分析方法,分别对回收试样的横截面和纵截面的晶粒的变形情况进行显微组织观察分析,解释MB2高温-高应变率下的变形机理主要是特定的滑移系上的晶粒经历了长大-滑移的变形机制。     

Nitrosation and Nitration of Tetraacetyldibenzylhexaazaisowurtzitane

Tetraacetyldibenzylhitane (TADBIW) was subjected to debenzylation by nitrosating with inorganic materials available commercially to synthesize tetraacetyldinitrosohexaazaisowurtzitane (TADNSIW). TADNSIW was purified, and its structure was determined by FTIR, 1H NMR, MS and element analysis. The debenzylation reaction of TADBIW gave quantitative benzaldehyde as a by-product. This indicates that the reaction produces an imine cation as an intermediate. Hexanitrohexaazaisowurtzitane (HNIW) was prepared from unpurified TADNSIW with the yield over 96.0 % and the purity more than 98.0 %. And the mechanism of the reaction from TADNSIW to HNIW is proposed to be oxidation of nitroso and nitration of acetyl on the molecule of TADNSIW, This reaction system involved is simple, and the reaction can complete within a short time and under mild conditions. The product can be easily to separate and the waste disposed readily.     

A Robust Algorithm for Watermarking 2D Vector Maps with Low Shape-Distortions

The technique of watermarking has been introduced into 2D vector maps for many potential applications such as protecting the copyright of important GIS （geographical information system） data and tracing the data source of military maps. In most previous works, although the validity of the map data could be preserved during the embedding procedure, the shape-distortions of the map elements are usually neglected which would tend to degrade the invisibility of the watermarking schemes. A shape-preserving algorithm for watermarking 2D vector maps is presented in this paper. A 1D distance sequence extracted from the original map is adopted as the cover data instead of 2D coordinates. A watermark bit is represented by changing the distributions of the cover data. The embedding procedure induces lower shape-distortions than in former works. Experimental results indicate better invisibility of the proposed scheme, as well as its robustness to certain attacks such as map simplification, interpolation, additive noise and most geometric transforms.     

Stability of the Third Generation Intensifier under Illumination

The stability under illumination of transmission-mode GaAs photocathode sealed in the third generation intensifier is investigated by use of spectral response testing instruments. The variations of spectral response with the illumination times under weak and intense illumination are compared. The variations of photoemission performance parameters are also characterized. The results show that during initial several weak illuminations photocathode behaves no evident decay and a maximum sensitivity is achieved, while under intense illumination the sensitivity of photocathode begin to decrease largely at the first illumination. The calculated performance parameters show that the variation of surface escape probability with illumination times is a direct cause of instability of photocathode. It is also found that under intense illumination peak wavelength is moved towards short-wave and peak response is decreased, which shows that the ability of long-wave response of photocathode is decreased.     

Open Rule-setting System Applied to Conceptual Design of Engines

Open rule-setting method advanced in this paper concentrates on providing designers of engines with a convenient way to express their design innovations and develop the expected prototypes in the early CAD stage, and constitute effective models for the following analysis process of CAE and CAPP. The problems arisen in the process of conceptual design with the traditional experience-based development method are analyzed. Based on those analyses, open rule-setting method is presented and some associated technical problems are discussed. The functional framework of open rule-setting system was built as software engineering methods. The speciality of the engine product as a kind of complex product and the requirement of the engine product based on its structural particularity to rule-setting system are considered carefully. A demonstration is supplied to illustrate how the open rule-setting method enhances the efficiency and quality of the engine conceptual design.     

Research on Linux Network Device Driver

By analyzing the working principle of Linux network device driver, discussing the Linux network driver structure and its key technologies, the general network driver structure and its design methodologies in Linux system are summarized. Through modifying the network device driver of Linux device driver 3rd version snull, c and improving the COW technology, the Zero-Copy technology in Linux （kernel version 2.6.11 ） is implemented. In the end, the success test tells us that the thorough analysis of network device driver is the foundation of many applications, and it also provides a certain improvement to a lot of real applications, even to military application development.     

Improvement and Experiment of the Reamer in Vibra Cutter Against Wave Edge of Titanium Sheet Alloy Parts

By analyzing the influencing factors of part quality making of sheet alloy of titanium by vibra cutter, the shape of upper reamer is set as cylinder and wedge-shaped form, and the lower reamer as plain and hemicycle form, and its main structural parameters are defined as well. Then it is validated further that such improved vibra cutter reamer can be used to process curve-edged parts of titanium alloy sheet. The experimental result shows that the titanium alloy sheet parts processed by above equipment have no sharpen angles for convex parts and evident crevasse of concave-edged part. In summary, such improvement can eliminate the free-waved edge and improve the manufacture quality of titanium alloy sheet parts greatly.     

Experimental Study on the Small Flyer Initiating Behavior of Fine-grained Explosives

The initiating behavior of fine-grained explosives by small flyer is studied. The diameter of small flyer in this device is 1 ram. The test results indicate that the granularity of explosives has great effect on its flyer initiating sensitivity.The flyer initiating sensitivity of the fine-grained explosives is higher and the critical initiating energy is lower than that of common explosives. For common explosive, the flyer initiating sensitivity increases as the density is reduced. But for the fine-grained explosive, the test results are exactly opposite.     

Passive Acoustic Radar for Detecting Supersonic Cruise Missile

A Passive Acoustic Radar is presented as a necessary complement to electromagnetic wave radar, which will be expected to be an effective means for detecting cruise missiles. Acoustic characteristics of supersonic flying projectiles with diverse shapes are expounded via experiment. It is pointed out that simulation experiment could be implemented using bullet or shell instead of cruise missile. Based on theoretical analysis and experiment, the ““acoustic fingerprint““ character of cruise missile is illustrated to identify it in a strong noise environment. After establishing a locating mathematical model, the technique of acoustic embattling is utilized to resolve a problem of confirming the time of early-warning, considering the fact that velocity of sound is much slower than that of light. Thereby, a whole system of passive acoustic radar for detecting supersonic cruise missile is formed.     

Algorithm for Multi-laser-target Tracking Based on Clustering Fusion

Multi-laser-target tracking is an important subject in the field of signal processing of laser warners. A clustering method is applied to the measurement of laser warner, and the space-time fusion for measurements in the same cluster is accomplished. Real-time tracking of multi-laser-target and real-time picking of multi-laser-signal are introduced using data fusion of the measurements. A prototype device of the algorithm is built up. The results of experiments show that the algorithm is very effective.     

Super-resolution Restoration of Remote-sensing Images

A novel image restoration scheme, which is super-resolution image restoration algorithm Poisson-maximum-afterword-probability based on Markvo constraint （MPMAP） combined with evaluating image detail parameter D, has been proposed. The advantage of super-resolution algorithm MPMAP incorporated with parameter D lies in the fact that superresolution algorithm MPMAP model is discrete, which is in accordance with remote-sensing imaging model, and the algorithm MPMAP is proved applicable to linear and non-linear imaging models with a unique solution when noise is not severe. According to simulation experiments for practical images, super-resolution algorithm MPMAP can retain image details better than most of traditional restoration methods; at the same time, the proposed parameter D can help to identify real point spread function （PSF） value of degradation process. Processing result of practical remote-sensing images by MPMAP combined with parameter D are given, it illustrates that MPMAP restoration scheme combined PSF estimation has a better restoration result than that of Photoshop processing, based on the same original images. It is proved that the proposed scheme is helpful to offset the lack of resolution of the original remote-sensing images and has its extensive application foreground.