喷涂层接触疲劳失效信号响应试验研究

采用超音速等离子喷涂设备制备了铁基自熔剂合金涂层，通过球盘式接触疲劳试验机考察了喷涂层的疲劳行为，使用扫描电子显微镜对涂层的截面和失效形貌进行了表征，研究了不同信号响应对涂层接触疲劳失效形式的指示作用。结果表明：在该应力水平下，喷涂层的接触疲劳失效形式为点蚀和分层失效。振动和扭矩信号的响应可以反馈不同的失效过程，点蚀失效过程中信号呈现渐变的特征，而分层失效过程中信号则发生明显的阶跃。     

基于任务冲击条件下弹药生产响应能力研究

在对弹药生产响应能力与生产速度关系分析的基础上,提出了基于任务冲击下,弹药生产响应能力的计算方法。对不同任务冲击度及生产速度约束条件下,弹药生产响应能力系数进行了对比,为任务冲击情况下弹药生产响应能力需求的确定提供参考。     

军事无线通信抗干扰装备及技术发展

以经典扩跳频抗干扰通信技术为切入点,综述了外军短波、超短波战术通信和数据链领域抗干扰装备和技术的发展现状,在此基础上,对通信抗干扰技术未来发展趋势进行了分析和预测。     

TDS-OFDM雷达通信共享信号波形设计

在使用正交频分复用(Orthogonal Frequency Division Multiplexing, OFDM)信号的雷达通信一体化系统中,循环前缀(Cyclic Prefix, CP)和导频的存在,使得共享信号在自相关运算中出现较高的副瓣电平,严重影响雷达检测性能。针对这个问题,提出一种新的基于时域同步OFDM(Time Domain Synchronization OFDM, TDS-OFDM)的共享信号形式,该信号利用训练序列填充保护间隔,同时完成同步与信道估计,从而避免了CP副瓣和导频副瓣的出现。首先分析TDS-OFDM共享信号的模糊函数,然后通过训练序列的优化设计,有效降低TDS-OFDM信号的距离峰值副瓣,同时保持训练序列自身良好的自相关性能。理论分析与仿真表明,相对于CP-OFDM,TDS-OFDM共享信号更加适用于雷达通信一体化系统。     

舰炮身管的模态分析与多目标优化

舰炮的炮口扰动是影响舰炮射击精度的重要因素。为了减少舰炮的炮口扰动,优化身管结构,建立了柔性身管的ABAQUS有限元模型,将有限元模型的模态计算值与模态试验值进行比较,发现建立的柔性身管有限元模型是合理可行的。提出了混沌量子粒子群算法与动力学联合优化的方法,进行身管和炮口的多目标优化。优化结果表明,优化后炮口中心的线速度、角速度和角位移与优化前相比显著减小,身管质量有所降低,结构更加合理,该优化方法有效可行,为下一步全炮总体优化设计提供了一定的借鉴。     

利用模态迭加法进行动响应分析应注意的问题

采用MSC-MARC程序的模态迭加法,对具有指数规律冲击载荷作用下的简支矩形板进行了响应计算,指出并讨论了应用模态迭加法求解结构动响应时应注意的几个问题.     

规则波浪中船舶操纵响应遭遇频率频散概念与机制

采用船舶单自由度横摇运动方程,以及纵摇与垂荡耦合摇荡运动方程,数值模拟了规则波浪中船舶操纵响应不规则摇荡运动现象。假定波浪中船舶遭遇频率具有谐波分量形式,定义了遭遇频率常量、强度和散射频率,提出了船舶遭遇频率频散概念,推导了遭遇频率的频散关系,分析得到了航速和浪向角度变化引起的两种频散机制。散射机制表明:顶浪航行时航速散射效率最高,正横浪航行时航向角散射效率最高。     

Study on dynamic response of multi-degree-of-freedom explosion vessel system under impact load

In order to study the dynamic response and calculate the axial dynamic coefficient of the monolayer cylindrical explosion vessel, the wall of vessel is simplified as a multi-degree-of-freedom (MDoF) undamped elastic foundation beam. Decoupling the coupled motion equation and using Duhamel's integrals, the solutions in generalized coordinates of the equations under exponentially decaying loads, square wave loads and triangular wave loads are calculated. These solutions are consistent in form with the solutions of single-degree-of-freedom (SDoF) undamped forced vibration simplified model. Based on the model, equivalent MDoF design method (also called MDoF dynamic coefficient method) of cylindrical explosion vessel is proposed. The traditional method can only predict the dynamic coefficient of torus portion around the explosion center, but this method can predict that of the vessel wall at any axial n dividing point position. It is verified that the prediction accuracy of this model is greatly improved compared with the SDoF model by comparing the results of this model with SDoF model and numerical simulation in different working conditions. However, the prediction accuracy decreases as the scaled distance decreases and approaches the end of the vessel, which is related to the accuracy of the empirical formula of the implosion load, the simplification of the explosion load direction, the boundary conditions, and the loading time difference.     

A high performance waveform and a new ranging method for the proximity detector

Signal modulation is an essential design factor for proximity detectors and directly affects the system’s potential performance. In order to achieve the advantages of chaotic codes bi-phase modulation (CCBPM) and linear frequency modulation (LFM) simultaneously, this paper designed a waveform which combined chaotic codes bi-phase modulation and linear frequency modulation (CCBPM–LFM) for proximity detectors. The CCBPM–LFM waveform was analyzed in the aspect of time delay resolution (TDR) and Doppler tolerance (DT) based on ambiguity function (AF). Then, a ranging method, which we called instant correlation harmonic demodulation (ICHD), was presented for the detector using the CCBPM–LFM waveform. By combining time domain instant correlation with harmonic demodulation, the ICHD solved the problem caused by combination modulation and made the most of the linear frequency modulation (LFM) harmonics and the correlation of chaotic codes. Finally, a prototype was implemented and ranging experiments were carried out. From the theoretical analysis and experimental results, the proximity detector used the CCBPM–LFM waveform has an outstanding detection performance.     

Dynamic modeling and parameter identification of a gun saddle ring

In this study, a theoretical nonlinear dynamic model was established for a saddle ring based on a dynamic force analysis of the launching process and the structure according to contact-impact theory. The ADAMS software was used to build a parameterized dynamic model of the saddle ring. A parameter identification method for the ring was proposed based on the particle swarm optimization algorithm. A loading test was designed and performed several times at different elevation angles. The response histories of the saddle ring with different loads were then obtained. The parameters of the saddle ring dynamic model were identified from statistics generated at a 50° elevation angle to verify the feasibility and accuracy of the proposed method. The actual loading history of the ring at a 70° elevation angle was taken as the model input. The response histories of the ring under these working conditions were obtained through a simulation. The simulation results agreed with the actual response. Thus, the effectiveness and applicability of the proposed dynamic model were verified, and it provides an effective method for modeling saddle rings.