DYNAMIC STABILITY AND ACTIVE CONTROL OF ELASTIC VEHICLES WITH UNSTEADY AERODYNAMIC FORCES MODELING

ＤＹＮＡＭＩＣＳＴＡＢＩＬＩＴＹＡＮＤＡＣＴＩＶＥＣＯＮＴＲＯＬＯＦＥＬＡＳＴＩＣＶＥＨＩＣＬＥＳＷＩＴＨＵＮＳＴＥＡＤＹＡＥＲＯＤＹＮＡＭＩＣＦＯＲＣＥＳＭＯＤＥＬＩＮＧＤＹＮＡＭＩＣＳＴＡＢＩＬＩＴＹＡＮＤＡＣＴＩＶＥＣＯＮＴＲＯＬＯＦＥＬＡＳＴ...     

SURGE FORECAST FOR AERONAUTICAL ENGINES WITH EXTENDED KALMAN ESTIMATION

ＳＵＲＧＥＦＯＲＥＣＡＳＴＦＯＲＡＥＲＯＮＡＵＴＩＣＡＬＥＮＧＩＮＥＳＷＩＴＨＥＸＴＥＮＤＥＤＫＡＬＭＡＮＥＳＴＩＭＡＴＩＯＮＳＵＲＧＥＦＯＲＥＣＡＳＴＦＯＲＡＥＲＯＮＡＵＴＩＣＡＬＥＮＧＩＮＥＳＷＩＴＨＥＸＴＥＮＤＥＤＫＡＬＭＡＮＥＳＴＩＭＡＴＩＯ...     

A MODEL FOR THE RELIABILITY ANALYSIS OF STRUCTURE UNDER RANDOM STRESS RANGE LOADINGS（RDCDR MODEL）

ＡＭＯＤＥＬＦＯＲＴＨＥＲＥＬＩＡＢＩＬＩＴＹＡＮＡＬＹＳＩＳＯＦＳＴＲＵＣＴＵＲＥＵＮＤＥＲＲＡＮＤＯＭＳＴＲＥＳＳＲＡＮＧＥＬＯＡＤＩＮＧＳ（ＲＤＣＤＲＭＯＤＥＬ）ＡＭＯＤＥＬＦＯＲＴＨＥＲＥＬＩＡＢＩＬＩＴＹＡＮＡＬＹＳＩＳＯＦＳＴＲＵＣＴＵＲ...     

EXPERIMENTAL AND NUMERICAL INVESTIGATIONS OF BOTH FLOW INDUCED CAVITY OSCILLATION AND ITS SUPPRESSION BY ACOUSTIC EXCITATION

ＥＸＰＥＲＩＭＥＮＴＡＬＡＮＤＮＵＭＥＲＩＣＡＬＩＮＶＥＳＴＩＧＡＴＩＯＮＳＯＦＢＯＴＨＦＬＯＷＩＮＤＵＣＥＤＣＡＶＩＴＹＯＳＣＩＬＬＡＴＩＯＮＡＮＤＩＴＳＳＵＰＰＲＥＳＳＩＯＮＢＹＡＣＯＵＳＴＩＣＥＸＣＩＴＡＴＩＯＮＬｕｏＢａｉｈｕａ；ＨｕＺｈａｎ...     

高阶各向异性k－ε模型及在直通道湍流流场中的数值研究

ＡＨＩＧＨ－ＯＲＤＥＲＡＮＩＳＯＴＲＯＰＩＣＫ－εＭＯＤＥＬＡＮＤＩＴＳＮＵＭＥＲＩＣＡＬＩＮＶＥＳＴＩＧＡＴＩＯＮＩＮＴＷＯＤＩＭＥＮＳＩＯＮＡＬＴＵＲＢＵＬＥＮＴＦＬＯＷＦＩＥＬＤＳＬｉｕＺｈｅｎｇｘｉａｎ，ＳｏｎｇＢａｏｊｕｎ，ＧｕＣｈｕａｎｇ...     

FINITE ELEMENT ANALYS IS AND OPTIMUM DESIGN FOR THE FRONT－FUSELAGE WITH SANDWICH CONSTRUCTIONS

ＦＩＮＩＴＥＥＬＥＭＥＮＴＡＮＡＬＹＳＩＳＡＮＤＯＰＴＩＭＵＭＤＥＳＩＧＮＦＯＲＴＨＥＦＲＯＮＴ－ＦＵＳＥＬＡＧＥＷＩＴＨＳＡＮＤＷＩＣＨＣＯＮＳＴＲＵＣＴＩＯＮＳＤｉｎｇＹｕｎｌｉａｎｇ；ＬｉｕＹｉ（Ｄｅｐｔ．ｏｆＶｅｈｉｃｌｅ，ＮａｎｊｉｎｇＵｎ...     

EXPERIMENTAL STUDY OF HIGH SUBSONIC CAVITY FLOW OSCILLATION AND ITS SUPPRESSION BY ACOUSTIC EXCITATION

ＥＸＰＥＲＩＭＥＮＴＡＬＳＴＵＤＹＯＦＨＩＧＨＳＵＢＳＯＮＩＣＣＡＶＩＴＹＦＬＯＷＯＳＣＩＬＬＡＴＩＯＮＡＮＤＩＴＳＳＵＰＰＲＥＳＳＩＯＮＢＹＡＣＯＵＳＴＩＣＥＸＣＩＴＡＴＩＯＮＬｕｏＢａｉｈｕａ（罗柏华）（ＳｃｈｏｏｌｏｆＰｏｗｅｒａｎｄＥｎｅｒｇ...     

CONSTITUTIVE MODEL AND DYNAMIC MECHANICAL PROPERTIES OF GLASSCLOTH/EPOXY LAMINATES AT DIFFERENT TEMPERATURES

ＣＯＮＳＴＩＴＵＴＩＶＥＭＯＤＥＬＡＮＤＤＹＮＡＭＩＣＭＥＣＨＡＮＩＣＡＬＰＲＯＰＥＲＴＩＥＳＯＦＧＬＡＳＳ┐ＣＬＯＴＨ／ＥＰＯＸＹＬＡＭＩＮＡＴＥＳＡＴＤＩＦＦＥＲＥＮＴＴＥＭＰＥＲＡＴＵＲＥＳＨＡＮＸｉａｏｐｉｎｇ（韩小平）１,ＨＡＮＳｈｅｎｌｉ...     

STUDY ON THERMAL EXPANSION COEFFICIENT AND DESIGN FOR ZERO－EXPANSION OF SlNGLE AND HYBRID MULTI－DIRECTIONA

ＳＴＵＤＹＯＮＴＨＥＲＭＡＬＥＸＰＡＮＳＩＯＮＣＯＥＦＦＩＣＩＥＮＴＡＮＤＤＥＳＩＧＮＦＯＲＺＥＲＯ－ＥＸＰＡＮＳＩＯＮＯＦＳｌＮＧＬＥＡＮＤＨＹＢＲＩＤＭＵＬＴＩ－ＤＩＲＥＣＴＩＯＮＡＬＣＯＭＰＯＳＩＴＥＳＺｈｏｎｇＷｅｔｈｏｎｇ；ＺｈａｎｇＺｕｏ...     

GRAIN STRUCTURE CONTROL OF NICKEL－BASE SUPERALLOYS IN CASTING PROCESS： EFFECT OF MELT ADDITIONS

ＧＲＡＩＮＳＴＲＵＣＴＵＲＥＣＯＮＴＲＯＬＯＦＮＩＣＫＥＬ－ＢＡＳＥＳＵＰＥＲＡＬＬＯＹＳＩＮＣＡＳＴＩＮＧＰＲＯＣＥＳＳ：ＥＦＦＥＣＴＯＦＭＥＬＴＡＤＤＩＴＩＯＮＳ￥ＬｉｕＬｉｎ；ＺｈａｎｇＲｏｎｇ；ＺｈｅｎｇＪｉａｎｇｂａｎｇ（Ｄｅｐｔ．ｏｆＡｐ...     

A novel imprecise stochastic process model for time-variant or dynamic uncertainty quantification

This paper proposes a novel model named as “imprecise stochastic process model” to handle the dynamic uncertainty with insufficient sample information in real-world problems. In the imprecise stochastic process model, the imprecise probabilistic model rather than a precise probability distribution function is employed to characterize the uncertainty at each time point for a time-variant parameter, which provides an effective tool for problems with limited experimental samples. The linear correlation between variables at different time points for imprecise stochastic processes is described by defining the auto-correlation coefficient function and the cross-correlation coefficient function. For the convenience of analysis, this paper gives the definition of the P-box-based imprecise stochastic process and categorizes it into two classes: parameterized and non-parameterized P-box-based imprecise stochastic processes. Besides, a time-variant reliability analysis approach is developed based on the P-box-based imprecise stochastic process model, through which the interval of dynamic reliability for a structure under uncertain dynamic excitations or time-variant factors can be obtained. Finally, the effectiveness of the proposed method is verified by investigating three numerical examples.     

守恒型可压缩一维湍流方法及其在超声速标量混合层中的应用

一维湍流（ODT）方法是一种能在一维计算域上遵循湍流基本物理规律的湍流建模方法。通过结合确定性和随机性求解方法,能够在一维计算域上准确捕捉到湍流统计规律,且降维建模可显著减小计算量。ODT方法主要被广泛用于不可压湍流和湍流燃烧研究,若要将其拓展用于模拟高速可压缩湍流,需对建模方法进行深度改进。相比于不可压ODT方法,本文基于欧拉参考框架,针对可压缩湍流的特性,将因变量由原始变量改为有利于减小可压缩湍流模拟误差的守恒通量,并加入了组分求解模块。对确定性和随机性求解模块均进行了相应的深度改进,开发出具有标量混合模拟功能的守恒型可压缩ODT方法。在确定性模块中改为求解以守恒通量为变量的一维截断控制方程,在随机性模块中构造一维涡时,将三联映射的作用对象也相应地由原始变量改为守恒通量,并选用了可保证变密度情况下动量守恒的双核变换。通过模拟空间发展超声速平面湍流混合层并将自相似阶段结果与实验结果比对,验证该方法对可压缩剪切湍流场中标量混合的捕捉精度。守恒型可压缩ODT方法模拟得到的速度场和组分场的平均剖面和脉动强度分布与实验结果准确吻合,精度明显优于传统的耦合梯度扩散亚格子模型的大涡模拟方法（LES-GRAD.DIFF.）以及耦合线性涡（LEM）亚格子模型的大涡模拟方法（LES-LEM）,且该方法的降维处理使其在降低计算成本方面具有显著优势。     

Helicopter aeroelastic analysis with spatially uncertain rotor blade properties

This paper investigates the effects of spatially uncertain material properties on the aeroelastic response predictions (e.g., rotating frequencies, vibratory loads, etc.) of composite helicopter rotor. Initially, the spatial uncertainty is modeled as discrete random variables along the blade span and uncertainty analysis is performed with direct Monte Carlo simulations (MCS). Uncertainty effects on the rotating frequencies vary with the higher-order modes in a non-linear way. Each modal frequency is found to be more sensitive to the uncertainty at certain sections of the rotor blade than uncertainty at other sections. Uncertainty effects on the vibratory hub load predictions are studied in the next stage. To reduce the computational expense of stochastic aeroelastic analysis, a high-dimensional model representation (HDMR) method is developed to approximate the aeroelastic response as functions of blade stiffness properties which are modeled as random fields. Karhunen–Loève expansion and a lower-order expansion are used to represent the input and outputs, respectively, in the HDMR formulation which is similar to the spectral stochastic finite element method. The proposed method involves the approximation of the system response with lower-dimensional HDMR, the response surface generation of HDMR component functions, and Monte Carlo simulation. The proposed approach decouples the computationally expensive aeroelastic simulations and uncertainty analysis. MCS, performed with computationally less expensive HDMR models, shows that spatial uncertainty has considerable influence on the vibratory hub load predictions.     

一种基于SFEM的构件振动疲劳强度可靠性的分析方法

由于构件的材料参数、几何参数及所受的载荷等均为随机变量,所以构件振动时的疲劳强度应通过随机参数来进行分析。振动构件疲劳强度的可靠度计算的随机有限元法可以有效地分析振动构件的疲劳强度可靠性,为提高构件疲劳强度的可靠性提供了理论依据。以悬臂梁为例进行了分析,通过实验验证了所给出方法的正确性。      

Research on the Plane Multiple Cracks Stress Intensity Factors Based on Stochastic Finite Element Method

Taylor stochastic finite element method (SFEM) is applied to analyze the uncertainty of plane multiple cracks stress intensity factors (SIFs) considering the uncertainties of material properties, crack length, and load. The stochastic finite element model of plane multiple cracks are presented. In this model, crack tips are meshed with six-node triangular quarter-point elements; and other area is meshed with six-node triangular elements. The partial derivatives of displacement and stiffness matrix with respect to all the random variables obtained by Taylor SFEM are derived. Meanwhile, the mean and variance expressions of SIF under uncertain factors are also derived. Parallel double-crack illustrative example of using the proposed method is given. The calculation results indicate that the uncertainty of SIF is influenced by the distance of the cracks, the smaller the distance of cracks is, the greater the SIF uncertainty is, and the uncertainties of material elastic modulus, load and crack length markedly affect the uncertainty of SIF; and the Poisson ratio of material has little influence. Among the variables, the elastic modulus has the greatest effect on SIF uncertainty. The next is external load. The crack length has lower effect on SIF uncertainty than both the elastic modulus and external load.     

飞机的随机变结构最优控制方法

 <正> 一、引言 系统的变结构控制(VSC——Variable Structure Control)方法,最初是由苏联学者Utkin等人提出来的,近二十年来发展非常迅速,并越来越多地应用于各个工业领域,其中包括航空部门。变结构系统(VSS——Variable Structure System)的主要特征是存在滑动模态。处于滑动模态时,系统的运动等价于一个低阶系统。研究表明,VSS比传统的控制系统有更好的优点:快速性,对参数变化及外加扰动有强鲁棒性以及实现简单等。然而,VSC的不足之处在于需要获得全部状态变量,这是很难保证的。     

随机型多目标决策的新方法

设计了一种多目标随机型决策分析新方法——交互式参考目标满足度与可行度法(IRGSD-FD),讨论了随机型决策分析的希望水平原则、解及替代模型的定义和确定性等价等问题,并对IRGSD-FD的应用结果进行了讨论。     

传统组合导航中的实用Kalman滤波技术评述

在随机线性系统建模准确的情况下,Kalman滤波是线性最小方差无偏估计。针对传统惯导/卫导组合导航的实际应用,难以精确建模,给出了常用的建模方法、状态量选取原则、离散化方法及滤波快速计算方法。讨论了平方根滤波、自适应滤波、联邦滤波和非线性滤波等技术的适用场合,并给出了使用建议。针对前人研究可观测度中未考虑随机系统噪声的缺陷,提出了更加合理的以初始状态均方误差阵为参考的可观测度定义和分析方法。提出了均方误差阵边界限制方法,可有效抑制滤波器的过度收敛和滤波发散。该讨论可为工程技术人员提供一些有实用价值的参考。