不锈钢薄板电子束填丝焊接间隙裕度研究

针对厚度为1.0mm的不锈钢板对接焊缝,进行了不同间隙的焊接试验,并测试了接头室温拉伸性能,研究了不锈钢薄板电子束填丝焊接对焊缝间隙的适应程度。     

扩展卡尔曼滤波对时变参数追踪性能的影响研究

扩展卡尔曼滤波（Extended Kalman filter,EKF）理论由线性卡尔曼滤波理论发展而来。在结构的物理参数未知的情况下,扩展卡尔曼滤波理论将结构的物理参数与其状态向量组成增广状态向量,对增广状态向量进行识别,从而得到修正的结构参数。本文引入扩展卡尔曼滤波理论,对结构参数进行识别。为了验证该方法的有效性,引入1个时变参数三自由度系统作为仿真算例,分别探讨扩展卡尔曼滤波中的各项滤波参数（模型噪声的协方差矩阵Q,测量噪声的协方差矩阵R）对结构的时变参数追踪性能的影响。结果表明,合适的滤波参数能使得算法更迅速,准确地识别出结构中的时变参数变化趋势。还通过一个悬臂梁仿真算例,证明了即使在部分测点没有测量的情况下,EKF算法也能识别出结构参数。     

Microstructures and fatigue properties of electron beam welds with beam oscillation for heavy section TC4-DT alloy

With the development of the manufacturing technology, electron beam welding（EBW） is capable of producing titanium alloy large parts in aero fields. To increase the applications and improve the properties, EBW with beam oscillation was investigated on TC4-DT alloy with50 mm thickness. We detected the welding samples by X-ray NDT, observed the microstructures of the welds, and tested the fatigue properties of the joints. The results showed that EBW with beam oscillation improved the weld morphology as well as welding quality, and the microstructure homogeneity of the welds and HAZ along the weld penetration were also improved. The fatigue properties of the joints with beam oscillation were more excellent than those of conventional EBW, even equal to those of the base metal under high stresses. The influences of the processing and the microstructure on the properties with beam oscillation were discussed.     

热处理对Pt-PtRh13薄膜热电偶绝缘层性能的影响及机理分析

为了测量航空发动机高温部件表面温度,利用离子束溅射镀膜技术制备了拥有多层薄膜结构的Pt-PtRh13薄膜热电偶,包括Ni基合金基底、Ni Cr Al Y黏结层、Al2O3过渡层、Al2O3绝缘层、Pt/Pt Rh13薄膜热电偶和Al2O3保护层。研究了热处理对Pt-PtRh13薄膜热电偶绝缘层性能的影响,并利用扫描电子显微镜(SEM)、X射线衍射分析(XRD)等手段对薄膜热电偶绝缘层性能下降的机理进行了分析。研究结果表明:利用Al2O3绝缘薄膜开发的Pt-PtRh13薄膜热电偶只用于900℃以下测温,在900℃以上长时间应用可能会出现测温不稳定问题,高温诱发Al2O3绝缘层发生晶型转变是主要原因。     

波音737CL机翼后梁主起落架支撑梁连接处腹板裂纹损伤修理

通过分析波音737CL飞机机翼后梁主起落架支撑梁连接处腹板裂纹损伤的具体情况,详细介绍了几种可选的修理措施,其中重点介绍了山东太古自主设计并获波音公司认可的腹板双搭接修理方案,此修理方案比其他修理方案维修周期短、修理成本低。     

损伤对平纹编织陶瓷基复合材料梁振动特性影响的试验研究

为研究平纹编织陶瓷基复合材料（CMCs）梁受损伤影响的非线性振动特性,本文分别开展了拉伸试验和振动试验。拉伸试验用于获得平纹编织CMCs受损伤影响的变刚度行为,多次正弦扫频试验用于获得振动载荷下平纹编织CMCs梁受损伤影响的非线性行为。拉伸试验得到的非线性应力-应变曲线表明材料受损伤影响变刚度行为明显。梁初始固有频率的试验值与理论值相比,相对误差小于1%。振动试验结果从两方面表明了损伤对梁振动特性的影响。一是模态参数的变化,固有频率从初始值（256.44Hz）不断减小,阻尼比呈现增大趋势,而共振位移幅值受固有频率和阻尼比的耦合作用发生非线性且非单调变化。固有频率的变化造成位移幅频特性曲线的左移现象。二是位移幅频特性曲线的多峰现象,在多处载荷频率下产生了位移峰值点。本文的试验结果可用于指导平纹编织CMCs结构动力学计算理论模型的建立。     

钛合金层合梁SPF/DB制造工艺研究

钛合金层合结构因具有较高的损伤容限而受到重视,并成为超塑成形/扩散连接技术应用的一个新方向.通过采用先超塑成形再进行热等静压扩散连接成为整体构件的SPF/DB组合工艺方法,可以实现钛合金层合结构波纹工字梁的制造,其外形尺寸、微观组织和性能等基本能满足设计使用要求,但其工艺参数仍有待通过深入研究进一步优化.     

二维耦合天线阵图结构模型在波束转换和失效分析中的应用

提出了耦合振荡器阵列的一种图结构模型,利用该模型对耦合振荡器阵列有源天线阵的波束转换时间、振荡器失效和耦合网络失效引起的阵列失效概率进行了分析和仿真。从分析结果看,阵列耦合网络具有一定冗余性的设计可以缩短阵列波束转换时间,提高阵列的可靠性。     

Effects of different aging treatments on microstructures and mechanical properties of Al-Cu-Li alloy joints welded by electron beam welding

Post-weld single aging treatment(solution treatment at 510 ℃ for 1 h, water quenching,and aging at 155 ℃ for 16 h) and post-weld double aging treatment(solution treatment at 510 ℃ for 1 h, water quenching, aging at 155 ℃ for 16 h, and aging at 130 ℃ for 12 h) are carried out on Al-Cu-Li alloy joints by electron beam welding(EBW) respectively. The effects of aging treatments on microstructures and mechanical properties of welded joints are investigated. Results show that the mechanical properties of welded joints are obviously improved after both aging treatments. The strength coefficient of joints is increased from 0.64 in an as-welded condition(AW) to 0.90 after post-weld double aging treatment. Microstructure analysis shows that the precipitates of the fusion zone within grains and grain boundaries are less in the AW condition. After post-weld heat treatment(PWHT), a lot of fine needle-like phases T_1(Al_2 Cu Li) precipitate in grain boundaries of the fusion zone, and more horseshoe-shaped β' (Al_3 Zr) particles precipitate within grains. In addition,grains of the fusion zone are refined after post-weld double aging treatment, which leads to an effect of grain refinement strengthening. Consequently, the mechanical properties of welded joints are greatly improved.     

星载干涉合成孔径雷达高度计波束指向优化设计新方法

基于干涉合成孔径雷达(InSAR)体制的星载高度计能实现高分辨率、宽幅、高精度海面高程测量。传统合成孔径雷达(SAR)系统波束指向设计方法以SAR图像近远端噪声等效后向散射系数差异最小化为优化目标,星载InSAR高度计对海入射角小,如采用传统波束指向设计方法将面临系统近端测高性能优于远端等问题。为使远端测高性能满足应用精度指标要求,系统需提高雷达发射功率或增大雷达天线尺寸,这对卫星系统提出了较高的要求。提出了面向测高应用的星载InSAR高度计波束中心指向设计新方法。该方法通过调整雷达波束中心指向实现全场景测高性能最优化,可有效降低传统设计方法中SAR载荷对发射功率等卫星指标的要求,对未来我国发展InSAR体制海面高度计系统设计具有重要的指导意义。仿真分析结果验证了新方法相对于传统设计方法的优越性。