基于自航式声诱饵对抗的机载鱼雷命中概率仿真

为研究潜艇使用自航式声诱饵对抗条件下直升机空投鱼雷命中概率,基于对舰艇引导直升机空投鱼雷的过程分析,建立了舰艇引导机载鱼雷攻潜的参数解算模型、自航式声诱饵对抗自导鱼雷模型,分析了鱼雷命中条件.以美国MK-46鱼雷为例,运用模拟法仿真研究了在自航式声诱饵对抗条件下机载鱼雷的攻潜效果,结论对自导鱼雷在对抗条件下攻击潜艇的作...     

石墨烯/Fe3O4复合材料的制备及电磁波吸收性能

为扩展石墨烯的应用领域,对磁性功能化石墨烯的电磁波吸收性能进行研究.在氧化石墨与Fe3 O4粒子的悬浮液中添加还原剂水合肼,微波辐照反应制备石墨烯/Fe3 O4复合物.采用X射线衍射、透射电镜等手段对材料的结构和Fe3 O4的分布状态进行了测试表征.采用矢量网络分析仪测定了材料在0.1～18.0 GHz频率范围内的复介...     

超高强度钢不同性质缺陷的声发射特性研究

研究了超高强度钢30Si2MnCrMoVE的声发射特性,针对裂纹、夹钨、未焊透等几种常见焊接缺陷的声发射数据进行了分析,为相关产品的声发射检测结果评定提供参考,以此提高声发射技术在超高强度钢产品质量检测上的可靠性。     

复合材料的边界吸湿模型

在研究复合材料层合板的吸湿和退湿过程中，常常采用菲克定理来描述水分在层合板中的扩散过程中，根据层合板表面浓度逼近平衡浓度的不同响应，提出了三类不同的边界条件模型来模拟复合材料层合板在不同环境介质下的水分扩散过程，并给出了计算吸湿量的解析解和有限差分数值计算方法。     

微波等离子推进器的原理与应用研究

简要介绍了空间动力装置的分类及其特点，重点分析和讨论新型空间动力装置－微波等离子推进器（ＭＰＴ）的基本原理，结构特征和应用前景。分析现有理论与实验研究结果后认为，ＭＰＴ是一种高比冲，长寿命的小推力动力装置，特别适合用作空间动力，进行航天器的轨道转移，姿态控制，位置保持，对接交会和星际航行，尽管目前ＭＰＴ仍处于理论探索与实验研究阶段，但研究结果表明，它是前景十分诱人的新型空间动力系统。     

NH3—NaSCH吸收式制冷系统性能分析

工作温度直接影响吸收式制冷系统的性能，而工作温度的选择受Ｇｉｂｂｓ相律和工质热力性质的限制。本文研究了ＮＨ３－ＮａＳＣＮ吸收式制冷系统的可能温度组合；有无回热器两种情况系统的热力参数和性能，如：吸收器和发生器中溶液浓度、循环倍率以及有无回热器时系统基于焓的性能系数等；分析了工作温度对系统性能的影响。结果表明，在无回热器时工作温度对系统性能的影响是不一致的。     

湿热环境下复合材料孔板压缩性能的研究

采用压缩试验的方法,对含孔机织碳纤维环氧复合材料层板进行了湿热环境下的压缩试验,研究了湿热环境对其压缩性能的影响。分析了复合材料孔板的吸湿特性、压缩强度、破坏模式及动态力学性能。结果表明:机织碳纤维环氧复合材料吸湿率较低,其饱和吸湿率仅为0.88%左右。湿热环境会降低由基体性能主导的压缩强度,130℃下湿态试样的开孔压缩强度保持率约为70%。含孔复合材料层合板的破坏模式均为过孔破坏,破坏均发生在应力集中的区域,并且断裂都是沿着应力集中最大的方向扩展。侧面断口主要为剪切失效,有分层和屈曲的特征。吸湿后复合材料的DMA Tg为125℃,比干态时下降了16℃。     

Energy absorption features of 3-D braided rectangular composite under different strain rates compressive loading

There are huge potential applications of 3-D braided composite in aerospace engineering because of the non-delamination feature of the composite under impact loading. This paper presents the analysis of energy absorption features of 3-D braided composite under compression with different strain rates. The 3-D 4-step rectangular braided composite coupons were tested on a material tester MTS 810.23 and a split Hopkinson pressure bar (SHPB) apparatus to obtain out-of-plane and in-plane compression stress vs. strain curves at quasi-static and high strain rate state. The failure modes and energy absorption features of the 3-D braided composite under different strain rates were analyzed both in time domain and frequency domain. The energy absorbed by the 3-D braided composite increases with the strain rate. From fast Fourier transform (FFT) analysis of compression stress vs. time histories, the power of energy absorption of the 3-D braided composite increases with strain rate and mostly concentrate on the high frequency region. While for quasi-static compression, the power distributes in very narrow frequency region and also is less than that in high strain rates. This feature corresponds to the different damage and energy absorption mechanisms of the 3-D braided composite under quasi-static and high strain rate compression.     

航空发动机压气机内部流体诱发声共振研究进展

声共振是一种涡声相互作用诱发的特殊声学共振现象，可产生超过160 dB的纯音噪声，不仅严重影响环境舒适性，还可引起结构件的疲劳破坏，在火箭燃烧室、军机弹仓、汽车天窗以及热交换器管束等多个工程领域内引起了设计者们的足够重视。与此同时，越来越多的研究表明航空发动机压气机内部同样存在声共振问题，其引发的叶片断裂故障也屡见不鲜，已逐渐成为国际范围内的一项研究热点问题，但对其物理机制的认识仍待完善。本文系统性阐述了压气机内部声共振的机理、试验测试、预测方法和控制措施的研究现状及其发展趋势，旨在扩展对流体诱发叶片振动方面的基础理论认知，为提升压气机设计和排故能力提供技术储备。     

Electron acoustic solitary waves in the Earth’s magnetotail region

Satellite observations have revealed solitary potential structures in the Earth’s magnetotail region. These structures have both positive (compressive) and negative (rarefactive) electrostatic potentials. In this paper we study the electron-acoustic solitary waves (EASWs) in an unmagnetized plasma consisting of cold plasma electrons and isothermal ions with two different temperatures. Using the reductive perturbation method, the nonlinear evolution of such structures is studied. The numerical computations are performed to study the role of two temperature ions in the generation of EASWs. In this case, the model supports the existence of both positive and negative electrostatic potentials with bipolar pulses. The electric field associated with these positive and negative solitary structures are numerically computed. The present study could be useful to construe the compressive and rarefactive electric field bipolar pulses associated with the BEN type emissions in the magnetospheric regions where the electron beams are not present.