涡轮动力装置闭环仿真试验器的设计与应用

针对涡轮动力装置电子控制器的控制逻辑检测和调试问题,本文提出了一种采用电子仿真试验器替代真实涡轮动力装置的方法。将电子仿真试验器与电子控制器构成闭环控制同路,从而实现对涡轮动力装置闭环运行过程的模拟。仿真试验表明,利用该电子闭环仿真试验器能较好地模拟涡轮动力装置系统的实际工况,为涡轮动力装置电子控制器的调试和检测提供了‘种简便、有效的途径,且能显著降低试验成本和危险性。     

液体成形复合材料力学性能测试方法研究进展

复合材料液体成形工艺(Liquid Composite Molding,LCM)是将液态聚合物在压力作用下注入铺有纤维预成形体的闭合模腔中,液态聚合物在流动充模的同时完成对纤维的浸润并经固化成形成为复合材料制品的一类制备技术。本文先对复合材料液体成形工艺原理进行了简要概述,接着综述了由液体成形工艺制备的复合材料构件的基本力学性能测试方法,其中基本力学性能主要包括拉伸、压缩、弯曲、剪切、开孔拉伸、开孔压缩、层间断裂和抗冲击性能等,并对相关的试验标准进行了比较。最后对液体成形复合材料的力学性能测试方法进行了总结和展望。     

飞机结构疲劳试验载荷的优化设计

提出用对载荷误差求极值的方法实现最小误差控制的试验载荷计算,并通过精度加权系数综合控制误差的合理分配,完成试验载荷的优化设计。该方法已经应用于某型飞机疲劳试验的试验载荷计算,为该机全尺寸疲劳试验的成功奠定了基础。     

飞机动力学虚拟样机技术

飞机动力学虚拟样机以研究飞机的动态特性为核心,通过虚拟样机各系统的建模与仿真,在系统开发和运行环境中对飞机的气动特性、控制系统、发动机特性、飞行性能和飞行品质进行分析、评估和研究,支持飞机的需求分析、方案论证、概念设计和初步设计,同时,飞行员可参与在回路中的操纵完成虚拟试飞验证。系统提供分布虚拟战场威胁环境,可在武器平台体系对抗环境中验证和评估飞机的作战效能。利用飞机动力学虚拟样机系统环境还可进行飞机的多学科优化设计。     

频率直方图法在复合材料检测中的应用

飞行器中复合材料结构的无损检测大多采用超声波检测方法。在实际检测过程中，类似碳纤维复合材料这样的特殊材料组织的结构比较复杂，所得到的超声波回波信号经常受到较强的结构噪声的干扰，信噪比较低，影响缺陷信号的识别。利用分离谱技术中最小值法，考虑结构噪声幅度对频率变化的敏感性，应用频率统计直方图法，对窄带信号的采样点进行统计、比较，选择绝对值最小的采样点信号作为输出信号，得到最佳频率检测带，对这些频带采用带通滤波器进行滤波，从而较好地将目标回波和结构噪声区分开，更准确地对复合材料构件讲行无损检测。     

乘波外形高超声速风洞测力试验研究

介绍利用气动设计方法构筑3种乘波外形模型在高超声速风洞中气动力测量的结果。试验Ma数为4.94、5.93和7.96,基于自由流条件的单位长度雷诺数分别为2.2×107/m、1.9×107/m和1.2×107/m。试验给出这3种构型模型在迎角范围-1°~8°下的力和力矩特性。讨论了Ma数和迎角变化对气动力和压力中心的影响,同时着重比较了3种乘波外形的升阻比特性。     

In-flight testing of the injection of the LISA Pathfinder test mass into a geodesic

LISA Pathfinder is a technology demonstrator space mission, aimed at testing key technologies for detecting gravitational waves in space. The mission is the precursor of LISA, the first space gravitational waves observatory, whose launch is scheduled for 2034. The LISA Pathfinder scientific payload includes two gravitational reference sensors (GRSs), each one containing a test mass (TM), which is the sensing body of the experiment. A mission critical task is to set each TM into a pure geodesic motion, i.e. guaranteeing an extremely low acceleration noise in the sub-Hertz frequency bandwidth. The grabbing positioning and release mechanism (GPRM), responsible for the injection of the TM into a geodesic trajectory, was widely tested on ground, with the limitations imposed by the 1-g environment. The experiments showed that the mechanism, working in its nominal conditions, is capable of releasing the TM into free-fall fulfilling the very strict constraint imposed on the TM residual velocity, in order to allow its capture on behalf of the electrostatic actuation.However, the first in-flight releases produced unexpected residual velocity components, for both the TMs. Moreover, all the residual velocity components were greater than maximum value set by the requirements. The main suspect is that unexpected contacts took place between the TM and the surroundings bodies. As a consequence, ad hoc manual release procedures had to be adopted for the few following injections performed during the nominal mission. These procedures still resulted in non compliant TM states which were captured only after impacts. However, such procedures seem not practicable for LISA, both for the limited repeatability of the system and for the unmanageable time lag of the telemetry/telecommand signals (about 4400 s). For this reason, at the end of the mission, the GPRM was deeply tested in-flight, performing a large number of releases, according to different strategies. The tests were carried out in order to understand the unexpected dynamics and limit its effects on the final injection. Some risk mitigation maneuvers have been tested aimed at minimizing the vibration of the system at the release and improving the alignment between the mechanism and the TM. However, no overall optimal release strategy to be implemented in LISA could be found, because the two GPRMs behaved differently.     

基于磁记忆技术对含缺陷焊缝的疲劳试验

对含有不同隐形损伤的40Cr焊板进行射线检测、疲劳试验和正交磁记忆信号测量，探索试件在疲劳应力作用下磁记忆信号的变化特征。试验结果表明：单一测量方式下的磁特征值不能表征焊板在疲劳循环载荷下的变化特征，所得结论存在偶然性；研究发现，可用磁场矢量梯度积分特征和磁场矢量合成梯度特征来评价焊板的疲劳损伤过程，并建立了以磁场矢量梯度特征为损伤参量的疲劳损伤模型，从而可以对含有隐形损伤焊接构件的疲劳寿命进行定量评估，为金属磁记忆技术在焊接缺陷定量评价上的进一步研究提供参考依据。     

Successes and challenges in non-destructive testing of aircraft composite structures

Composite materials are increasingly used in the aerospace industry. To fully realise the weight saving potential along with superior mechanical properties that composites offer in safety critical applications, reliable Non-Destructive Testing (NDT) methods are required to prevent catastrophic failures. This paper will review the state of the art in the field and point to highlight the success and challenges that different NDT methods are faced to evaluate the integrity of critical aerospace composites. The focus will be on advanced certificated NDT methods for damage detection and characterization in composite laminates for use in the aircraft primary and secondary structures.     

通信卫星真空热试验测试电缆集中控温方法

为解决通信卫星真空热试验中有效载荷的部分测试电缆工作温度超出正常区间导致电缆相位特性发生极大跃变的问题,文章设计了一种新型电缆控温方法,实现了测试电缆在真空低温复杂环境下的集中控温。在某新一代通信卫星真空热试验中,应用该集中控温方法后测试电缆网的温度被严格控制在40℃±5℃,单根电缆沿路径的温度差异被控制在±3℃之内,满足了星上有效载荷的时序和相位要求,提高了地面测试的准确性。