飞机结构典型环境腐蚀当量关系研究

 提出了一种用DFR值描述飞机结构的疲劳性能随腐蚀时间变化的关系式。阐述了腐蚀损伤相同则疲劳强度相等的观点，明确提出了以疲劳强度为准则的腐蚀当量原理，并根据相当数量的大气暴露和加速腐蚀试验后的疲劳数据，确定了铝合金试件4种典型环境地面停放大气腐蚀与试验室加速模拟环境暴露的腐蚀当量关系。     

A Novel Approach for the Effective Thermal Conductivity of Porous Ceramics

A new approach in combination of the effective medium theory with the equivalent unit in numerical simulation was developed to study the effective thermal conductivity of porous ceramics. The finite element method was used to simulate the heat transfer process which enables to acquire accurate results through highly complicated modeling and intensive computation. An alternative approach to mesh the material into small cells was also presented. The effective medium theory accounts for the effective thermal conductivity of cells while the equivalent unit is subsequently applied in numerical simulation to analyze the effective thermal conductivity of the porous ceramics. A new expression for the effective thermal conductivity, allowing for some structure factors such as volume fraction of pores and thermal conductivity, was put forward, and the results of its application was proved to be close to those of the mathematical simulation.     

TA15钛合金薄板氩弧焊对接焊缝疲劳特性研究

在TA15薄板材料标准试件的疲劳试验结果和轧制板材试件成组疲劳试验结果处理的基础上,通过TA15薄板氩弧焊、磨削对接焊缝试件的疲劳试验,采用当量应力集中系数法,确定了中值当量应力集中系数和安全当量应力集中系数,建立了该TA15薄板焊接件的S-N、p-S-N曲线,最后给出分析结论与工程应用建议。     

直－九直升机地面共振当量模型及稳定性分析

本文推导了直升机地面共振当量模型中的当量质量、当量刚度与当量阻尼的计算公式，分析了机体动力特性及其主要影响因素，并运用当量地面共振二维模型计算了直一九直升机旋翼／机体耦合地面共振稳定性。在此基础上分析了机体阻尼与旋翼阻尼各自对直－九直升机地面共振稳定性的影响。计算与分析结果表明，未国产化的直－九直升机在使用范围内不会发生地面共振，这与直一九宜升机实际使用情况相符合。所用计算模型及计算机程序可直接用于直－九直升机国产化中地面共振稳定性分析。     

方框图化简中相加点和分支点互换方法探讨

简化控制系统方框图常用的方法有方框图等效变换法和Mason公式法。对于复杂系统的方框图，用Mason公式法求解控制系统的传递函数，这个过程较为繁琐，易于出错。基于此，探讨了相加点和分支点互换的移动方法以及使用步骤，并通过实例论证其简单可行，具有较强的实用性。     

基于500 Hz OH-PLIF技术的超声速燃烧室火焰结构

针对超声速燃烧室火焰驻留时间短和高湍流度的特点,利用500 Hz高频OH-PLIF(planar laser induced fluorescence)技术,研究了氢燃料超声速燃烧室火焰结构,结合壁面压力,获得了点火、稳焰以及熄火过程的规律。结果表明：隔离段入口来流马赫数为2的情况下,氢气当量比0.1和0.3,在火花塞点火下,2 ms均能点燃并获得PLIF火焰图像,其中当量比为0.1凹槽内存在爆燃现象,火焰达到稳定燃烧状态较慢(约65 ms)。稳焰过程中,当量比为0.3燃烧相对不充分,燃烧区域更靠近下壁面,燃烧位置和火核位置变化较大。当量比为0.1和0.3,熄火时间均在6 ms内,其中当量比为0.1熄火时火焰是从凹腔中部传播到凹腔前缘位置熄灭并伴随有一个短暂火焰增强的过程,并且在传播至凹腔前缘时已接近熄灭,当量比为0.3在熄灭前则是慢慢变弱,最终在凹腔前缘至喷氢位置间熄灭。     

追踪及凝视状态下地气光对空间目标成像影响

为了分析不同探测方式下地气光辐射对空间目标成像特性的影响,利用卫星仿真工具包(satellite tool kit,STK)设计了一个以地球同步轨道(geosynchronous orbit,GEO)卫星与中轨道(medium orbit,MEO)卫星上搭载的可见光成像器为探测平台,以高椭圆轨道(highly elli...     

TC4钛合金锥形环热辗轧应变及温度场对轧辊尺寸的响应规律

 提出采用等效半径来描述锥形轧辊(驱动辊和芯辊)及锥形环坯的呈线性变化的径向尺寸,进而建立了确定锥形环件辗轧关键工艺参数合理范围的方法。基于ABAQUS软件平台,研究建立了TC4钛合金锥形环热辗轧三维热力耦合有限元模型,进而模拟阐明了TC4钛合金锥形环热辗轧过程应变及温度场对轧辊尺寸(等效半径)的响应规律与机理。主要结果表明:随着驱动辊等效半径增大,环件内侧等效塑性应变及温度明显增大,环件温度分布越均匀;随着芯辊等效半径增大,环件内侧等效塑性应变及温度明显减小,温度分布越不均匀;驱动辊和芯辊各存在一个最佳的等效半径,使得环件应变分布最均匀。     

径向间隙及加工工艺对气体箔片轴承性能的影响

为了分析轴承的加工工艺和径向间隙对轴承静态、动态性能的影响,设计搭建了静态、动态实验台,利用改变轴颈尺寸的方法研究不同径向间隙对气体箔片轴承(GFB)静态性能和动态性能的影响,还分别研究了不同波箔弹性结构、不同箔片材料和不同波箔热处理方式等因素对轴承性能的影响.结果表明:随着径向间隙减小,气体箔片轴承静刚度及其动态结构刚度增大,其等效黏性阻尼随着径向间隙的减小,出现先增大后减小的趋势.在工艺上箔片材料及波箔弹性结构对轴承性能的影响起重要作用.     

A type of 2D magnetic equivalent circuit framework of permanent magnet for magnetic system in AEMR

Modeling of permanent magnet(PM) is very important in the process of electromagnetic system calculation of aerospace electromagnetic relay(AEMR). In traditional analytical calculation, PM is often equivalent to a lumped parameter model of one magnetic resistance and one magnetic potential, but great error is often caused for the inner differences of PM; based on the conception of flux tube, a type of 2D magnetic equivalent circuit framework of permanent magnet model(2D MECF) is established; the element is defined, the relationship between elements is deduced, and solution procedure as well as verification condition of this model is given; by a case study of the electromagnetic system of a certain type of AEMR, the electromagnetic system calculation model is established based on 2D MECF and the attractive force at different rotation angles is calculated; the proposed method is compared with the traditional lumped parameter model and finite element method(FEM); for some types of electromagnetic systems with symmetrical structure, 2D MECF proves to be of acceptable accuracy and high calculation speed which fit the requirement of robust design for AEMR.