长寿命热障涂层的剥落机理及抗剥落结构设计

涂覆于高温合金热端部件表面的热障涂层,具有隔热防护作用,属新一代燃气轮机的关键核心技术。等离子喷涂制备的热障涂层隔热性能好,但长时间高温服役后存在开裂剥落问题,引发基体烧蚀、造成巨大经济损失。因此,发展长寿命热障涂层是该技术领域的重大难题。本文从等离子喷涂热障涂层的独特层状结构特征入手,阐述涂层在高温服役中结构和性能的演变规律,揭示涂层剥落失效机理,总结长寿命热障涂层设计方法。研究表明,等离子喷涂热障涂层呈现以连通2D孔隙为主的层状多孔结构,具有优异的隔热功能和协调应变能力。然而,涂层在高温服役中发生烧结,2D孔隙大量消失,涂层显著刚化,使热障涂层开裂驱动力急剧增加,引发微观裂纹扩展并贯通形成大尺度裂纹,导致涂层最终剥落失效。据此,分别从降低开裂驱动力和增加开裂阻力两方面着手,总结抗开裂新结构涂层设计方法,为研发长寿命热障涂层指明了发展方向。在未来研究中,如何保证涂层高隔热和长寿命并同时兼顾经济性,是发展新一代高性能热障涂层的重点方向。     

基于优化最小二乘支持向量机的小样本预测研究

统计学中的预测问题主要是通过对已知数据的分析,找到数据内在的相互依赖关系,从而获得对未知数据的预测能力。该文提出了最小二乘支持向量机参数优化方法———多层动态自适应优化算法,构建了基于最小二乘支持向量机的预测模型,并对Ti 26合金的性能预测进行了研究。结果表明:优化的最小二乘支持向量机具有优秀的小样本数据学习能力和预测能力。     

Polymer dynamics applied to PEEK matrix composite welding

Continuous composite processes such as thermoplastic automated tow placement are based on fusion bonding or healing of thermoplastic matrix. A good understanding of interdiffusion and crystallization, the main phenomena at the interface, is important. In order to investigate self-bonding in PEEK (Poly-ether-ether-ketone) and then in the same matrix reinforced by carbon fibers, a new experimental device has been developed allowing to prepare short-time welded samples which were then mechanically characterized using a wedge double cantilever beam test. The corresponding data on mode I critical strain energy release rate as function of processing conditions clearly show that both interdiffusion across the interface and crystallization are key parameters for the strengthening of the interface. Thermal modeling has also been developed and explains the importance of the interface cooling curve for healing.     

牛顿迭代收敛的加速

基于Newton迭代法单根的二阶收敛性和重根的线性收敛性,提出了加速牛顿迭代收敛的思想。利用反函数的性质,取Taylor展开式的前三项进行迭代;并利用差商代替导数的方法,构造出更高收敛阶的迭代公式。大量的数值实验结果表明,本文算法理论上的推导是完全可行的,且有效地提高了迭代公式的收敛速度。     

最大应变记忆元件

 本文介绍的新型的应变测试元件——最大应变记忆元件,具有记忆构件上曾经历过的最大应变值的功能。在不跟踪测量的情况下,可以得知构件上曾经历过的最大应变值,使用方便,灵敏度高。     

用再结晶法研究超载对疲劳裂纹扩展的效应

 本文用再结晶法测定了等幅循环载荷中施加超载后在裂纹尖端发生的高应变区内的塑性应变,求得了此区域的各参数与J积分、裂纹尖端张开位移CTOD及超载对疲劳裂纹扩展的延缓效应。实验结果表明,用再结晶法研究超载对裂纹扩展的延缓效应是一种很有效的方法。     

压气机叶栅中的激波附面层相互作用

压气机叶栅中激波附面层相互作用是十分复杂的问题,由于相互作用引起分离是决定跨音速压气机性能的重要因素之一。然而迄今为止,尚未深入进行过压气机叶栅激波附面层相互作用的研究,发表的文献极少。作者经过计算和分析,说明压气机叶栅流中主要的相互作用形式是叶栅槽道中激波和湍流附面层的相互作用。作者通过分析指出,研究压气机叶栅激波附面层相互作用,不能直接应用Pearcey分离准则。作者并提出了适用于压气机叶栅的分离准则的函数关系为f(M_1,p_1/p_(L.E.),P_(r.E.)/p_2,Re_0)=O。     

面内弯曲载荷作用下两边简支两边固支复合材料层合板的屈曲

为扩充航空复合材料结构稳定性设计手段,基于Levy形式级数和有限差分法,提出了面内纯弯曲载荷作用下两边简支两边固支（SSCC）复合材料层合板临界屈曲载荷的数值解法。首先,应用有限差分法将挠度函数进行离散化处理;然后利用边界条件扩充方程组,最后将临界屈曲载荷的求解转化为广义特征值问题。通过数值算例分别在各向同性板和复合材料层合板上验证了本文方法,并与有限元方法（FEM）进行了比较。结果表明,本文方法具有很高的精度,为复合材料层合板的屈曲分析开辟了新的途径。     

满足恒应变速率等温锻的注油方程及离散化处理

 采用传统制造工艺制作的高温合金涡轮盘往往出现晶粒度粗大。不均匀以及宏、微观偏析等问题。这不仅会引起涡轮盘力学性能的不均匀性,而且降低了合金的强度、延性和抗疲劳性。采用粉末冶金制造工艺可有效地改善盘件的冶金质量,使组织均匀,晶粒细化,提高了力学性能和使用的可靠性。我国近年来进行了FGH95（相当于Rene 95）粉末涡轮盘的研制工作。FGH95粉末盘通过热等静压和等温锻造成型,由于热等静压后的坯料原始     

单边缺口板材试样的J积分试验标定

 单边缺口试样的J积分,当取其缺口内表面为积分回路时,有特别简单的形式,即,并可进一步简化为,其中。 本文对两种单边缺口试样（缺口根部曲率半径ρ分别为20毫米和9毫米）,测定了缺口内表面的应变分布ε（θ）,再经应力-应变曲线转换成形变功密度分布W（θ）,最后通过数值积分求出系数A。试验结果与考虑了Weiss塑性区修正的线弹性断裂力学方法做了比较。     

村镇银行可持续发展的制约因素及对策研究——以河南省为例

村镇银行是我国新型农村金融机构的一种基本形式和新生银行形态,对农村社会经济发展具有不可或缺的重要作用.文章以农业大省河南为例,通过描述性研究和个案分析,深入系统地剖析了影响和制约河南村镇银行可持续发展的制度、功能、社会、定位、风险、结算和人力等诸多因素,并从村镇银行的外部保障环境营造、内部经营机制完善和国外经验借鉴等方面,提出了河南村镇银行可持续发展的基本路径和一系列对策建议.     

计算轮盘破裂转速的大变形解析法

本文为轮盘破裂转速研究课题组的研究报告之一。文中提出的大变形解析法是计算轮盘破裂转速的一种新方法, 首先推导了基本方程, 其次叙述了计算步骤, 并对几个试验盘作了数值计算。最后将计算结果与试验结果作了对比, 误差均在 4 %以内。作者认为, 此法简便易行, 准确度符合工程需要, 适应范围较大, 可以在发动机轮盘研制工作中应用。      

航空发动机真实机匣的包容性试验

为了研究某发动机机匣的包容性, 在旋转试验器上进行了该机匣的包容性试验.试验考虑了相邻叶片的影响, 得到了叶片断裂甩出时的转速、断叶撞击机匣的应变响应和断叶撞击机匣过程的高速摄影照片.试验结果表明, 断叶与机匣碰撞了两次, 第2次撞击时在未断叶片作用下断叶击穿机匣, 机匣的失效模式主要是剪切破坏.采用包容曲线法对机匣的包容性进行了计算, 计算结果与试验结果吻合良好.研究结果对航空发动机机匣的包容性设计有一定的参考价值.      

Effect of Variable Selection on Multidisciplinary Design Optimization： a Flight Vehicle Example

Different multidisciplinary design optimization (MDO) problems are formulated and compared. Two MDO formulations are applied to a sounding rocket in order to optimize the performance of the rocket. In the MDO of the referred vehicle, three disciplines have been considered,which are trajectory, propulsion and aerodynamics. A special design structure matrix is developed to assist data exchange between disciplines. This design process uses response surface method (RSM) for multidisciplinary optimization of the rocket. The RSM is applied to the design in two categories: the propulsion model and the system level. In the propulsion model, RSM deter-mines an approximate mathematical model of the engine output parameters as a function of design variables. In the system level, RSM fits a surface of objective function versus design variables. In the first MDO problem formulation, two design variables are selected to form propulsion discipline. In the second one, three new design variables from geometry are added and finally, an optimization method is applied to the response surface in the system level in order to find the best result. Application of the first developed multidisciplinary design optimization procedure increased accessible altitude (performance index) of the referred sounding rocket by twenty five percents and the second one twenty nine.     

An adaptive-order particle filter for remaining useful life prediction of aviation piston pumps

An accurate estimation of the remaining useful life (RUL) not only contributes to an effective application of an aviation piston pump, but also meets the necessity of condition based maintenance (CBM). For the current RUL evaluation methods, a model-based method is inappropriate for the degradation process of an aviation piston pump due to difficulties of modeling, while a data-based method rarely presents high-accuracy prediction in a long period of time. In this work, an adaptive-order particle filter (AOPF) prognostic process is proposed aiming at improving long-term prediction accuracy of RUL by combining both kinds of methods. A dynamic model is initialized by a data-driven or empirical method. When a new observation comes, the prior state distribution is approximated by a current model. The order of the current model is updated adaptively by fusing the information of the observation. Monte Carlo simulation is employed for estimating the posterior probability density function of future states of the pump’s degradation. With updating the order number adaptively, the method presents a higher precision in contrast with those of traditional methods. In a case study, the proposed AOPF method is adopted to forecast the degradation status of an aviation piston pump with experimental return oil flow data, and the analytical results show the effectiveness of the proposed AOPF method.     

A new fourth-order processing algorithm for spaceborne SAR

A new fourth-order signal aperture radar (SAR) processing algorithm has been developed for a general satellite-Earth relative motion. The two-dimensional exact transfer function (ETF) is calculated and range-variant phase corrections have been calculated in order to process many azimuth lines per block. The ETF together with the phase corrections has been called the fourth-order EETF (extended ETF). It is also shown that a fourth-order EETF is necessary to process high quality images from spaceborne SAR with long integration times with spatial resolution around 1 m. The algorithm is fast and is anticipated to have good phase preservation properties     

亚音速升力面理论的一种新解法

本文提供了亚音速升力面理论的一种新解法,可求解亚音速流中有限翼展机翼的载荷分布。计算中采用传统的弦向级数和展向分条。证明了Mangler二重奇异积分可交换积分次序,从而使积分可解析地求出。对弦向积分的被积函数作多项式分段逼近,可使核函数的表达式成为封闭形式的有限和,导致性态很好的系数矩阵。计算结果与实验及其它方法的结果作了比较,并给出了计算效率。     

铁电材料研究进展及其在飞行器上的应用

铁电材料是具有驱动和传感 2种功能的机敏材料,可以块材、膜材 (薄膜和厚膜 )和复合材料等多种形式应用,在微电子机械和智能材料与结构系统中具有广阔的潜在应用市场。近年来铁电陶瓷材料获得很大发展,例如弛豫型铁电陶瓷,反铁电 -铁电相变型铁电陶瓷都取得了实际应用。铁电材料中大应变弛豫型铁电单晶材料研制成功,是近 50年来取得的突破性进展。主要介绍了智能材料与结构相关的铁电材料特点及其在飞行器上的应用前景     

Effect of a Few Dominant Specular Reflectors Target Model Upon Target Detection

Some data indicate that aircraft targets viewed from certain aspects are well modeled as consisting of a few specular reflectors. The effect of a simplified form of this target model upon radar detection performance for two different waveforms has been analyzed. The signal-to-noise ratio (SNR) required for detection as a function of waveform bandwidth for a conventional-single-channel waveform and for a four-channel frequency diversity waveform is evaluated. It is shown that for either waveform there is an optimum bandwidth to minimize the SNR required for detection. In addition, the single-channel minimum is less than the four-channel minimum. The best performance occurs for the single-channel waveform when the waveform bandwidth just resolves the individual reflectors. For typical targets, this bandwidth is of the order of 35 to 75 MHz. It is also shown that only a 0.8-dB loss relative to this minimum is incurred when using a four-channel narrow bandwidth waveform.     

激光全息图像测量自动条纹计数

 在图像测最中,干涉条纹图像并不代表定最结果,而其中的各干涉条纹所具有的条纹级数则是精确测试计量的唯一重要依据。条纹图像判读的主要任务就是条纹计数,即经过识别对各条纹赋以条纹级数,使定性的条纹分布转化为定量的形式。 判读条纹图像有多种方法,如人工判读、机械扫描式判读和数字条纹图像判读处理。