RDX基PBX的本构行为与应变历史、应变率效应（英文）

高聚物粘结炸药(PBX)作为一种典型的颗粒填充弹性材料,其力学性能与应变率、应变历史密切相关。利用材料试验机获得了浇注PBX在准静态应变率范围内(10~(-4)~10~(-2)/s)的循环加载、卸载应力-应变曲线。用DorfmannOgden模型分析了PBX的本构行为。结果表明,该PBX具有应变率效应,循环加载过程中存在应力软化和滞回现象,卸载过程中存在残余应变现象。材料损伤可用滞回环和残余应变的大小来表征,损伤程度主要受最大加载应变控制。在DorfmannOgden模型中,只有剪切模量(μ)受加载速率影响。10~(-4),10~(-3),10~(-2)/s下的μ值分别为43.94,56.92,71.93 MPa。该模型可以较好地描述材料的应力软化和残余应变行为。预测结果与试验数据吻合良好。     

以RDX为基的浇注PBX力学性能与本构模型

为研究一种黑索今(RDX)基浇注高聚物粘结炸药(PBX)的力学性能与本构模型,利用INSTRON材料试验机及改进分离式Hopkinson压杆(SHPB)进行了准静态和动态单轴压缩实验,获得了材料在10-4~10-2s-1及843~1490 s-1应变率范围内的应力-应变曲线。结果表明:该浇注PBX的变形过程分为线性段、强化段和软化段。准静态加载下该浇注PBX具有明显的应变率效应,其弹性模量、压缩强度、临界应变与相对对数应变率之间近似呈线性关系;而在实验应变率范围内,动态加载下特别是加载初期应变率效应不明显,同时发现其破坏准则由应力控制,材料在12MPa附近发生破坏。借鉴推进剂及橡胶材料本构关系的研究结果,分别提出了能描述浇注PBX一维动、静态压缩力学行为的率相关本构模型,该模型与实验结果误差小于10%吻合较好。     

两种炸药材料本构行为的应变率效应分析

对PBX和B炸药两种压装炸药进行了应变率为10-4～102s-1的压缩实验,得到了两种炸药材料在不同应变率下的应力-应变曲线;通过回收试样的SEM观测,对材料的破坏模式进行了细观考察;初步建立了材料在高应变率下的本构模型;对两种炸药力学行为的特征和应变率效应得到了较系统的认识.     

金属材料在高应变率下的热粘塑性本构模型

提出了一种考虑应变强化、应变率强化、热软化效应及材料损伤的本构模型,通过在Johnson-Cook热粘塑性本构关系中增加一个随应变增大应力减速小的软化项,反映材料的损伤.该模型可以很好地预测材料的整个变形过程,同时提供了一个确定软化项系数的简单方法.     

碳/环氧复合材料的冲击拉伸

该文研究了T300碳纤维单向增强的环氧复合材料,在应变率从10~(-3)/s到10~3/s范围内的冲击拉伸行为.通过对实验数据进行拟合,得出该范围内材料对应变率具有弱的敏感性,表现在破坏强度及破坏应变随应变率增加不显著变化,平均模量几乎不受应变率的影响.分析了试件的几何尺寸效应,讨论了应力波作用对破坏形态的影响以及实验中观察到的拔出现象.从应变率在10~2～10~3/s附近材料行为某些非确定性,指出在更宽范围内了解其性能的必要性.     

三种含能材料力学行为应变率效应的实验研究

利用分离式霍普金森杆和万能材料试验机对复合固体推进剂(CSP)、高聚物粘接炸药(PBX)和B炸药(Comp．B)三种材料进行了高应变率和准静态压缩实验，得到了常温常压下，不同应变率的材料应力一应变曲线，对这三种材料本构行为的应变率效应进行了研究。     

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。     

电铸Ni-W合金高应变率下的流变应力特征

利用Gleeble-1500型热模拟机和分离式Hopkinson压杆实验装置,对700℃下退火2 h的电铸Ni-W合金进行压缩试验,测定合金在准静态条件(10-3~10-1s-1)和高应变率(650~2 200 s-1)下的应力-应变曲线。结果表明,在高应变率条件下,电铸Ni-W合金具有应变率增强、增塑及应变强化效应。高应变率下的塑性变形过程中产生的绝热升温对材料起软化作用。基于Johnson-Cook(J-C)本构模型,引入绝热温升软化项对模型进行修正,通过实验数据拟合得到电铸Ni-W合金的动态塑性本构关系。     

高应变率下导弹战斗部装药动态力学响应 及细观损伤模式

应用改进的SHPB实验技术实现了常应变率加载,激光测量系统监测实验试件轴向工程应变,高速相机拍摄试件变形过程,确保实验数据的可靠性,进而对导弹战斗部装药在高应变率下的动态力学响应及损伤形式进行实验研究,并结合扫描电子显微镜探索其细观损伤模式与高应变率加载条件的内在关联。结果表明,该导弹战斗部装药具有明显的应变率效应,当其应变值超越0.05时应变率效应显著增强,随着加载应变率的提高,其应力应变曲线应变硬化效应显著增强,由上凸形式变为线性硬化;在860～1 380 s~(-1)加载应变率下,其主要细观损伤形式为颗粒表面与粘结剂剪切脱粘,当加载应变率在1 380～2 300 s~(-1)区间时,充足的冲击波能量迫使晶体颗粒表面产生损伤裂纹,并沿应力集中薄弱路径不断扩展,传播路径错综复杂,进而产生晶体颗粒破碎现象。     

中高应变率条件下TC18钛合金动态力学行为的实验研究

应变和应变率是影响材料力学行为的两个重要因素,分离式霍普金森压杆（SHPB）技术是实现不同应变和应变率加载的有效途径之一。为研究室温下TC18钛合金的塑性变形和破坏行为,采用SHPB,通过调节子弹长度和速度实现对TC18钛合金圆柱试样不同应变和应变率的加载。实验得到了TC18钛合金在不同应变率下的真应力-真应变曲线和同一应变率不同应变下的真应力-真 应变曲线,并分别分析了应变硬化和应变率强化效应对TC18钛合金的动态力学性能的影响。实验结果表明：TC18钛合金压缩试样破坏时断口与加载方向（轴线）之间的夹角约为45°,其压缩破坏形式为典型的剪切破坏,与应变和应变率相关;应变率越高,TC18钛合金的流动应力和屈服强度越高,故该材料具有明显的应变率强化效应;绝热剪切带是裂纹形成和试样发生宏观剪切破坏的先兆。     

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.     

Expert Systems Aimed at General Design of Projectiles

Expert systems aimed at the general design of projectiles can implement a series of intelligent designs, such as the design of HE shell, the scheme expounded and proved, the emulation analysis and calculation, etc. Aiming at the product design feature, the expert system adopts the object-oriented knowledge representation and all kinds of inference control engines to describe and reason the relevant knowledge regarding the product through the microcomputer. It embodies the foundation of emulation analysis and simulated manufacturing of the shell. It makes use of the method that knowledge expression is combined with condition of inference to carry out the overall design and emulation and reference.The paper gives the ways through which the functions can be achieved, gives the modularization of reference and the design methods of systematization, puts forward the method of knowledge expression and working interface, and supplies a platform for similar products of the shell category that can be quickly designed.     

Parameter Identification for the Valve Control Cylinder System of a Hydraulic Manipulator

In mechanical, hydraulic and electronic systems, the determination of system parameters is often challenging because liquid parameters often change significantly, due to variations in working and environmental conditions. Therefore, it is of significant practical importance to identify those parameters through experimental procedures. A systematic approach to identifying parameters in the valve controlling cylinder system of hydraulic manipulators is provided. It first derives the transfer function of the system, and then uses P control of PID control to predict system parameters. The predicted parameters are further validated using PID control. The prediction through simulation using MatLab language is utilized, which agrees well with experimental results.     

Software Communication Architecture Implementation and Its Waveform Application

This paper attempts to do a research on the development of software defined radio（SDR） based on software communication architecture（SCA）. Firstly, SCA is studied and a whole reference model of SCA3.0 core framework （CF） is realized; Secondly, an application-specific FM3TR waveform is implemented on the platform of common software based on the reference model; Thirdly, from the point of view of real-time performance and software reuse, tests and validations are made on the above realized CF reference model and FM3TR waveform. As a result, the SCA-compliant SDR has favorable interoperability and software portability and can satisfy the real-time performance requirements which are not too rigorous.     

Three-dimensional Numerical Simulation of Combustion Field in the Combustion Chamber

In order to study the effect of rotation on the combustion in the underwater vehicle, a two-phase turbulent combustion process is described with Reynolds stress turbulence model, eddy-dissipation turbulent combustion model, P-1 radiation model and particle tracking model of liquid. The flow in the rotating combustion chamber is simulated at two different working speeds, 0 r/min and 1 000 r/min by Fluent software. The temperature, gas velocity, static pressure of wall and fuel concentration are computed and compared. The results show that the combustion in rotating combustor is faster and more effective.     

Dynamic Simulation of the Tank Gun Recoil Response

By using the ATV module of MSC. ADAMS, the dynamic simulation of recoil response of tank gun is analyzed.How the recoil force affects the bodywork and the suspension during gun firing, as well as the changing status of the gun muzzle‘s velocity are gained. All results and analyzing methods are offered for the designing basis of optimizing tank vehicle-gun match. The constructive exploration is beneficial to improving the general capability of tank.     

Survey of Controllable Suspension System for Off-road Vehicles

The controllable suspension system can improve the performances of off-road vehicles both on road and cross-country. So far, four controllable suspensions, that is, body height control, active, semi-active and slow-active suspensions, have been developed. For off-road vehicles, the slow-active suspension and the semi-active suspension which have controllable stiffness, damping and body height are more appropriate to use. For many years, some control methodologies for controllable suspension systems have been developed along with the development of modern control theory, and two or more original control methods are integrated as a new control method. Today, for military or civilian off-road vehicles, the R&D of controllable suspension systems is ongoing.     

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.     

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.     

Design and Simulation of TF and TA Controller for Missile

A nonlinear terrain following(TF) and terrain avoidance(TA) controller is proposed for missile control systems. Based on classical TF algorithm (adaptive angle method), a new method for TF controller is proposed by using angle of attack. A method of obtaining terrain outline data from digital elevation map (DEM) for TF control is discussed in order to save store space. A TA algorithm is proposed by using bank-to-turn technique. The block control model, which is suitable for backstepping design, is given for nonlinear model of missile. Making full use of the characteristics of the system and combining block control principle and backstepping technique, a robust controller design method is proposed. Uncertainties in every sub-block are allowed, and can be canceled by using the idea of nonlinear damping. It is proved that the state tracking errors are converged to a neighborhood of the origin exponentially. Finally, nonlinear six-degree-of-freedom simulation results for the missile model are presented to demonstrate the effectiveness of the proposed control law.