钛合金板抗12.7mm穿甲燃烧弹厚度效应试验研究

采用12.7 mm穿甲燃烧弹对不同厚度的Ti-6Al-4V钛合金板进行厚度效应试验,研究钛合金板厚度对其防护能力的影响。采用等重钢总穿深及防护系数的方法考核其抗弹性能。结果表明,钛合金板抗小口径枪弹(12.7 mm穿燃弹)板厚在10~30 mm间厚度效应呈现正效应。     

Defeating Mechanisms of Armours for Main Battle Tanks

The fundamental protection principles of the new armours for main battle tanks against kinetic energy projectiles(KE) and chemical energy weapons (CE)——shaped charges are shortly described and their efficiency against both threats discussed. The armour topics can be split into: “perpendicular or zero-degree armours”, such as rolled homogeneous armour (RHA), also with extremely high strength, ceramics, glass, liquid filled columns and explosive filled cells,“inclined armours”, as spaced RHA plates with their corner effects, bulging armour, additive and integrated explosive reactive armours (ERA) and “hard kill active defence possibilities” in different defeating distances.     

Simulation of the Crashing of Sandwich Structures under Impact Loads by Movable Cellular Automata

Movable cellular automata (MCA) method is applied in the analysis of dynamic characters of ceramic armor composite structures under impact loading. As a new approach, MCA is different from the traditional numerical methods such as the finite element method and boundary element method. Based on the theory of particle mechanics, MCA is applied as a powerful tool in relying specific structural analysis of materials loss and penetrating damages. In this paper the method is used to study responses of multi-layered ceramic plates as a base of armor structures under impact loading, thus assisting further investigations in the crashing process and to improve ceramic armor structures.     

Vibration Control of High-speed Cannonball Transport Mechanism Driven by Impact

A method is presented to control the vibration of high-speed cannonball transport mechanism due to the reduction of its weight, which adhere a nonlinear Zn-27Al-1Cu damping alloy layer and a constraint layer partly to the part of mechanism driven by impact. Based on the equivalent viscous damping theory and using curve fitting to describe the rule of the dissipation factor of damping alloy changing with stress, the nonlinear constitutive relation of Zn-27Al-1Cu damping alloy is given. The nonlinear spring damping contact model is adopted to describe the contact force of the clearance joint.Based on the nonlinear finite element contact theory, the outer impact contact force between the mechanism and its working environment is analyzed, and a coupled dynamic model of structural impact and mechanism motion with clearance joint is put forward. A dynamic model is established for the cannonball transport mechanism partly adhering Zn-27Al-lCu damping alloy layer and constraint layer under complex impact conditions. At last, the feasibility of the method presented is proved by numerical simulation.     

负荷特性对电力系统低频振荡的影响

负荷作为电力系统的重要组成部分,其特性对互联电网低频振荡具有重要的影响。本文在研究了电力系统低频振荡基本分析方法和电力负荷基本特性的基础上,建立了考虑动态负荷特性的用于研究低频振荡的电力系统线性化模型,形成多机系统的状态矩阵。以4机2区系统为研究对象,采用模态方法分析系统状态矩阵的阻尼比等结果随系统负荷模型参数变化的变化轨迹,从而获得不同负荷特性对系统低频振荡的影响。     

在阻尼作用下叠加相干态压缩特性的时间演化

本文讨论了由一对相干态｜α＞和｜－α＞而产生的叠加相干态（薛定谔猫态）在具有阻尼的情况下压缩特性随时间的演化,特别讨论了场的高阶压缩性质受阻尼的影响．在场模形成的初始阶段,高阶压缩性质是不稳定的,高阶压缩参量将随时间出现振荡,场态将出现几次压缩和非压缩的交替变化．随时间的推移,场的压缩状态终将趋于稳定,压缩参量的绝对值减小并趋于零．阻尼的增加将加快这一演化过程,并且阻尼将削弱压缩．     

液体介质中厚度切变石英晶体传感器的特征阻尼研究

本文提出一个新概念：特征阻尼系数ｋｃ。用来区分液体中振荡的厚度切变石英晶体传感器由质量负载和液体阻尼分别引起的频率偏移。理论推导表明，当石英晶体表面附着的质量没有变化时，特征阻尼系数Ｋｃ０的大小与附着的液体或固体性质无关，只取决于晶体谐振器自身的参数，如基频、电极面积和谐波次数等。     

线性时变动力系统参数识别方法与试验分析

根据时变频率的定义由时变动力系统的响应计算瞬时频率,由自由衰减响应或希尔伯特阻尼谱识别瞬时阻尼特性。采用2层框架结构数值模型验证了识别方法的可行性,进而应用于12层短肢剪力墙结构振动台实验及识别模型结构在试验过程中动力性能的时变特性。将识别所得瞬时阻尼比代入有限元模型中计算结构响应,并与常值阻尼比及实测结果进行了对比。结果表明,采用时变阻尼比的计算结果更接近实测响应,文中方法可以反映结构的时变动力特性。     

一种基于离散实镜像理论的修正物理光学法在金属平行板内嵌电大尺寸结构中的应用

传统的物理光学法(PO)能够方便高效地处理开放空间中电大尺寸结构的电磁散射问题,并且通常能获得较好的精度。然而,对于电大尺寸结构内嵌在金属平行板之间的这种特殊问题,传统的PO方法不再适用,而采用全波分析方法来处理往往需要消耗巨大的计算资源。该文在离散实镜像理论的基础上,提出了一种修正的物理光学法(DRMI-PO),基本思想是先将金属平行板间的激励电磁流展开为傅里叶级数,再对级数的每一项分别应用2维物理光学法求解场,最后把所有求得的场解作线性组合。与多层快速多极子(MLFMA)的全波方法相比,DRMI-PO在解决该类特殊结构的电磁仿真问题时能在保证足够高精度的同时大幅度提高计算效率;作为应用实例,对两种不同极化方式的太赫兹波段扇形波束扫描天线分别进行了DRMI-PO数值仿真与实验测试,结果表明仿真和实验得出的天线方向图吻合较好,从而证实了DRMI-PO方法的有效性。     

Ultra-Damping Composites Enhanced by Yolk–Shell Piezoelectric Damping Mechanism

High-performance damping materials are significant toward reducing vibration and maintaining stability for industrial applications. Herein, a yolk–shell piezoelectric damping mechanism is reported, which can enhance mechanical energy dissipation and improve damping capability. With the addition of yolk–shell particles and carbon nanotube (CNT) conductive network, damping properties of various resin matrices are enhanced with the energy dissipation path of mechanical to electrical to heat energy. Particularly, the peak loss factor of epoxy composites reaches 1.91 and tan δ area increases by 25.72% at 20 °C. The results prove the general applicability of yolk–shell piezoelectric damping mechanism. Besides, the novel damping materials also exhibit excellent flexibility, stretchability, and resilience, offering a promising application toward damping coating, indicating broad scope of application in transportation and sophisticated electronics, etc.