EXO3晶振与KSS晶振在高过载下的失效特性分析

为了研究芯片抗高过载能力,本实验选取两种典型晶振芯片:EXO3、KSS,利用Hopkinson杆对其进行高g值冲击,以一维应力波理论估计芯片受到的加速度,并用运力学模型对其内部结构进行分析。结果表明:晶振的内部结构直接影响它的抗冲击性能;与应力波传播方向平行放置的晶振抗冲击性能要高于与应力波传播方向垂直的晶振。     

弹载加速度记录仪在冲击环境下的失效研究

在弹体侵彻过程中,首先分析高g值冲击对弹载加速度记录仪的影响,得出应力波作用下加载到弹体内记录仪的加速度值,并研究了加速度记录仪壳体、缓冲材料及电路板的动态结构响应,进而提出可能出现的失效模式：壳体结构的失效、缓冲材料缓冲性能的不足、芯片与PCB板相对运动导致芯片的裂纹。针对各失效模式,利用ANSYS/LS-DYNA对记录仪各防护单元进行了数值模拟仿真,得出各防护单元失效的临界冲击加速度值: 电路板失效的临界冲击加速度为1.93×104g,当加载冲击加速度为1.63×105g时,壳体发生屈曲;增大冲击加速度至5.63×106g时,缓冲材料失效。经过实弹侵彻试验,得出记录仪在1.5×105g的冲击加速度下失效。该实验结果对后续弹体实际侵彻弹载记录仪的设计及优化提供数据支撑。     

车载式汽车碰撞多参量测试系统的研制

本文介绍了一种自行研制的用于汽车碰撞多参量测试的32通道车载测试系统,该仪器选用12位高速A/D芯片,选用复杂可编程逻辑器件CPLD作为控制电路,缩小了系统体积,提高了系统可靠性,实现了多通道的同步、高速采集的控制,采用特殊的灌封工艺实现了高冲击条件下的大量数据的可靠存储.该测试系统已在长春一汽国家汽车质量监督检验中心进行检测试验,并成功获取了测试数据.     

支链型乙烯基硅油改性有机硅灌封材料的性能

采用支链型乙烯基硅油改性的端乙烯基硅油为灌封硅橡胶的基础胶,并分别以沉淀法和气相法白炭黑进行补强,研究了不同用量和品种白炭黑补强对灌封材料的黏度、力学性能、粘接性能和电学性能的影响。结果表明,当401-1500/411-4800=100/15时,灌封材料黏度适中并且力学性能较好;沉淀法白炭黑加入量在20phr～25phr时,灌封材料具有较好的工艺性能,拉伸强度最大值达到2.27MPa,剪切强度最大值达到4.64MPa,电绝缘性良好。     

原位聚合法制备环氧树脂/纳米SiO2灌封材料的性能研究

采用原位聚合法制备了环氧树脂/纳米SiO2灌封材料.用透射电镜(TEM)、扫描电镜(SEM)、差热扫描量热法(DSC)等方法研究了材料的结构与性能.结果表明,环氧树脂/纳米SiO2灌封材料的冲击强度和弯曲强度随纳米SiO2含量而变化,当其含量为3%(质量分数)时二者出现最大值,与纯环氧树脂固化物相比冲击强度和弯曲强度分别提高了98%和112%.同时纳米SiO2的加入也使灌封材料的电性能和热性能得到改善,线膨胀系数明显降低,环氧树脂的粘度稍有增加.     

小口径火炮弹底压力测试系统抗高过载研究

针对小口径火炮的高过载环境和狭小测试空间可能导致弹底压力测试系统芯片失效,导线以及焊点脱落和断裂的问题,开展弹底压力测试系统抗高过载研究。建立了芯片失效和测试仪器隔离缓冲机理模型,研究了芯片不同安装方向的抗高过载性能,以及不同缓冲材料的抗高过载性能,得出了芯片抗过载能力与安装方向的关系,以及不同缓冲材料的抗过载性能的差异;在此基础上提出了环氧树脂真空灌封方法,解决了测试仪在高过载环境下导线以及焊点脱落和断裂的问题;最后通过实弹测试验证了弹底压力测试系统的存活性和可靠性。研究结果对小口径火炮弹底压力测试系统的设计具有重要意义。     

液体橡胶改性环氧灌封树脂的制备

本文主要介绍了应用端环氧基丁腈橡胶改性环氧树脂得到新型灌封树脂的研制过程。试验结果表明:新型灌封树脂选用的树脂、固化剂增加了韧性链段,而TEM图显示液体橡胶增韧剂在固化物中形成了"海岛结构",这三方面使得新型灌封树脂具有较好的抗开裂性能,冲击强度提高了100%。     

固化剂对MG/PU/TDE-85灌封材料性能的影响

以磨碎玻璃纤维(MG)为填料,分别采用甲基四氢邻苯二甲酸酐(MeTHPA)、甲基纳迪克酸酐(MNA)为固化剂,通过聚氨酯(PU)对4,5环氧环己烷1,2-二甲酸二缩水甘油酯(TDE-85)改性,研究了MG/PU/TDE-85/MeTHPA和MG/PU/TDE-85/MNA两种灌封材料的力学性能、热性能和电性能。研究结果表明,两种灌封材料都具有很高的力学性能、热性能和电性能。与MG/PU/TDE-85/MNA灌封材料相比,MG/PUTDE-85/MeTHPA灌封材料的拉伸强度、半寿温度、体积电阻较高,而冲击强度、玻璃化转变温度略低。     

MEMS矢量水听器声压通道封装技术研究

为了更全面地获取水下声场信息,微机电系统(Micro-Electro-Mechanical System,MEMS)矢量水听器常需集成声压敏感通道来提升单个换能器性能,MEMS矢量水听器的敏感芯片采用的是MEMS工艺制备完成,其封装必须与水隔离,传统的橡胶灌封方式会破坏MEMS敏感芯片的机电性能,故MEMS敏感芯片常采...     

纳米SiO2/环氧树脂灌封材料的研究

以纳米SiO 2作为增强材料,制备了纳米SiO2/环氧树脂灌封材料,并研究了不同的纳米含量对灌封材料性能的影响,采用透射电镜(TEM)对纳米SiO2粒子分散情况进行了分析.结果表明,纳米SiO2均匀地分散在环氧树脂基体中,有效地改善了环氧树脂的力学性能,并且当纳米SiO2含量为3%时,纳米SiO2/环氧树脂灌封材料的力学性能最佳,其冲击强度和弯曲强度比环氧树脂分别提高98%和112%,同时电学性能也有所提高.     

基于弹丸爆炸毁伤效应的复合材料与结构研究进展

军用地面装备的方舱化已成为当代不可逆转的发展趋势,但由于结构特点的限制,军用方舱的防护能力较弱。为了提高方舱在现代战争中的生存能力,基于弹丸爆炸毁伤效应的复合材料与结构的研究受到世界各军事强国的高度重视,得到了全面发展。弹丸爆炸的毁伤效应主要包括高速破片的侵彻效应与冲击波的破坏效应,文章回顾了军用方舱的发展历程,从防破片侵彻、防冲击波破坏以及防复合破坏效应等方面详细综述了复合材料与结构的研究进展和应用现状。     

Effect of in-bore gas on railgun performance

Acceleration of a projectile in a nonevacuated railgun bore produces a series of shock waves traveling through the gas in front of the projectile which retards the projectile's motion. A model is presented which describes the three components of this retarding force-the force required to accelerate the gas to the projectile velocity as it is entrained by the shock front, the force required to continue to accelerate previously shocked gas as the projectile accelerates, and the force required to overcome the viscous drag which arises from the interaction of the shocked gas and the gun tube. The authors address the relative contributions of the three components of the force and the significance of the retarding force when compared to the net accelerating force. The validity of the strong shock approximation for computing the retarding force is discussed     

眼护具冲击测试仪的研制

根据国家标准计量局制订的防冲击眼护具试验方法的国标要求 ,提出一种眼护具冲击测试仪的研制方案 ,实现对防护眼镜和防护面罩的安全性能进行可靠精确的检测。文中具体阐述了系统工作原理 ,发射装置设计 ,及基于单片机加CPLD双片结构的信号处理装置硬件设计和程序流程。试验结果和试运行情况表明该仪器达到了预期的性能指标和要求     

A wave propagation model for the high velocity impact response of a composite sandwich panel

A solution methodology to predict the residual velocity of a hemispherical-nose cylindrical projectile impacting a composite sandwich panel at high velocity is presented. The term high velocity impact is used to describe impact scenarios where the projectile perforates the panel and exits with a residual velocity. The solution is derived from a wave propagation model involving deformation and failure of facesheets, through-thickness propagation of shock waves in the core, and through-thickness core shear failure. Equations of motion for the projectile and effective masses of the facesheets and core as the shock waves travel through sandwich panel are derived using Lagrangian mechanics. The analytical approach is mechanistic involving no detail account of progressive damage due to delamination and debonding but changes in the load-bearing resistance of the sandwich panel due to failure and complete loss of resistance from the facesheets and core during projectile penetration. The predicted transient deflection and velocity of the projectile and sandwich panel compared fairly well with results from finite element analysis. Analytical predictions of the projectile residual velocities were also found to be in good agreement with experimental data.     

冲击波叠加效应对组合式多爆炸成型弹丸成形的影响研究

为探明组合式多爆炸成形弹丸（MEFP）弹丸的成形机理、研究形成良好弹丸的关键因素,运用LS-DYNA显式动力学软件对同时起爆和时差起爆条件下组合式MEFP成形过程进行了数值模拟计算,并对多个子装药爆轰场冲击波叠加效应进行了理论分析。研究表明：导致中心弹丸易于断裂、速度较快,周边弹丸形状不对称的主要原因是侧壁和罩顶反射冲击波的叠加作用;选用低密度吸能效果较好的填充介质可以减小反射波的强度从而减弱其叠加效应;当起爆时差超过5µs,中心子装药的药型罩会出现过度压垮的现象,不利于弹丸的成形。研究成果为战斗部填充介质的选取、合理装药间距的确定、多点起爆器材精度的确定等关键技术提供了理论依据     

Hugoniot measurement by hyper-velocity impact at velocities up to 9 km/s using a two-stage light-gas gun under optimized shot conditions

The optimization for acceleration of a projectile was performed by varying piston mass in consideration with the correlation with projectile mass and the engineering limits of the two-stage light-gas gun, and the projectile velocity has been achieved 9.2 km/s using the optimum acceleration conditions. Moreover, the Hugoniot measurements of oxygen-free copper were performed using the line reflection method at pressures up to 380 GPa by symmetric impact. The tilt and curvature of shock front were investigated according to the impact velocity, and it is proved to be important that the continuous spatial profile of shock front would be recorded.     

外围部件互连总线接口电路设计方案的研究

本文在研究PCI（Peripheral Component Interconnect）总线即外围部件互连总线的基础上，对采用专用接口芯片 CPLD和高速CPLD器件 PCI软件包的两种PCI总线接口设计方案。在性能，成本及设计复杂程度等方面进行了分析和比较，提出了一种采用S5933 CPLD实现通用高速PCI接口电路的设计方案。     

Soft acceleration of a metal plate by a rail gun plasma

The following situation is considered: A dense plasma armature which has been accelerated to a high velocity in a rail gun is allowed to impact a stationary metal plate. At impact, a shock wave is transmitted into the plate and a shock wave is reflected back into the plasma. For very high plasma velocities, the subsequent behavior depends primarily on the plasma density profile just prior to impact. The appropriate partial differential equations are analyzed in plane geometry and the conditions required to prevent spallation of the plate are determined. These results are compared with the "plasma only" armature plasma profiles predicted by Sloan, and it is shown that the conditions for not spalling the metal are well satisfied. The typical rail gun makes use of a low mass plasma armature to continuously accelerate a more massive solid projectile down the length of the rails. It has been suggested that substantially higher velocities and energies may be achievable with a "plasma only" rail gun-which has no solid projectile, but which has an armature mass comparable to the mass of a solid projectile. Subsequent to the acceleration, the momentum of this high velocity plasma must be transferred to a solid projectile. One way to do this is to simply allow the plasma to collide with the projectile. For this to be of interest, the projectile should not shatter and the energy transfer should be reasonably efficient. The purpose of the paper is to analyze an idealized model of such a collision.     

The use of metal foam projectiles to simulate shock loading on a structure

Metal foam projectiles are used to generate dynamic pressure–time histories representative of shock loading in water and air. A 1D plastic shock wave analysis is performed for a foam projectile impacting a free but rigid mass. It is shown that the pressure versus time pulse exerted on the mass and the shock arrest distance within the foam depend upon the ratio of foam mass to impacted mass, and upon the ratio of quasi-static to hydrodynamic strength of the foam. The theory is supported by two sets of experiments, one where Alporas foam impacts an instrumented Kolsky pressure bar, and one where the foam is fired at a free mass. It is demonstrated that the magnitude and duration of the pressure pulse can be controlled by suitable adjustment of the velocity, length and density of the foam projectile.     

超高速撞击压力容器碎片云与气体介质相互作用建模研究

针对超高速撞击压力容器碎片云与气体介质相互作用问题,首先,建立了碎片云的初始模型;然后,应用气固两相流理论对碎片云与气体介质的相互作用进行分析,建立了计算模型,并通过与实验结果的比较,验证了计算模型的有效性。在此基础上,考察了弹丸直径、撞击速度及气体介质压力对碎片云与气体介质相互作用的影响。研究结果表明:碎片云的尖端速度及径向扩展速度均随着弹丸直径的增加而增加,气体冲击波强度随着弹丸直径的增加而增强;随着撞击速度及气体介质压力的增加,碎片云尖端减速运动的加速度及径向减速运动的加速度均增大,气体冲击波强度随着撞击速度及气体介质压力的增加而增强,并且衰减速度增大。