地震预报问题明显说明了固体地球物理学的现状和发展

在谈到近些年来地球科学方面的最重要成就时说: 没有固体地球物理学,没有它的方法的应用,就不可能有目前获得矿产的成就,就不可能有目前同自然灾害斗争的成就。如果没有这门科学,就不会有航海和航天飞行。随着人类生活和各个活动领域中发生的问题日益增多,地球物理学家必须不断发展和完      

基于遗传算法的飞机气动优化设计

建立了一种以实数编码技术为基础的遗传算法模型，并把它与通过工程估算的气动分析方法相结合，进行飞机气动形的单点和多点优化设计。 优化设计中，设计变量取机为机翼、机身和尾翼的外形及三者之间的相对位置，优化目标是使飞机在跨音速和超音速飞行状态下获得配平状态下最大的升阻比。设计结果表明该优化设计方法是十分有效的，可以用来具有正常布局形式的飞机进行气动外形的优化设计。     

疲劳强度研究动态

金属疲劳是一个很复杂的现象。常常在较低的应力水平上,出乎人们意料之外地发生了疲劳破坏。许多结构在使用初期就已有许多看不见的微观裂纹。为了估计结构的疲劳性能,第一要考虑疲劳环境,也就是要估计飞机在什么样的环境中使用。这就要估计气候条件、机动飞行、地面运行情况、飞机用途等等。对飞机的疲劳环境不很清楚的话,飞机受力的情况也就不很清楚,这是飞机疲劳强度研究中首先遇到的一个问题。即使我们有了飞机外界载荷的统计数据,我们也要根据飞机结构的外界载荷分布和飞机的动态响应来估计飞机各部件所受的力。所以飞机动态响应是面临的第二个问题。知道了每个部件的受力情况、受力历史,接着的问题是:怎样估计疲劳寿命;出现裂纹后,怎样估计     

AIRCRAFT CONTROL SURFACE FAULT DIAGNOSIS AND EVALUATION OF FLIGHT PERFORMANCE

针对操纵面故障将严重影响飞机的飞行安全，提出一种能快速实现故障诊断及性能评估的系统方法。首先，当系统状态维数较高时，采用容积卡尔曼滤波算法的球形积分准则和径向积分准则优化Sigma 点的采样策略和权重分配，较好地解决了无迹卡尔曼滤波算法滤波性能明显下降的问题；然后，利用飞机等速平飞运动特征计算故障下的升力系数和阻力系数，得出能反映飞机性能的飞行包线；最后，通过仿真结果验证了本文所提方法的可行性。     

用三维光弹性和应变片电测技术分析大型飞机主起落架的应力

主起落架是大型飞机重要的部件，其结构和载荷都十分复杂。为对主起落架进行详细的应力分析，本文不但提出一种整体制作主起落架三维光弹性模型的方法；而且将应变片电测技术应用于光弹性模型上，成功地为主起落架关键部件——活塞杆进行了方案的优化，并使其最大应力下降了４０％；同时提出一种载波计算机自动测量边界应力的方法。以上说明，对主起落架等复杂而重要的结构，实验应力分析方法是一种优化设计的有效工具。     

疲劳研究动态

人们对疲劳的研究已经有一百多年的历史。最初,有人发现用韧性金属做成的零件,在承受重复载荷时会发生一些脆性断裂,而同样的载荷在静力作用下并不发生破坏。以后,人们逐渐发现,在某些振动激烈反复加载严重的区域(如飞机发动机、操纵系统等)以及金属零件的接头,往往从开槽或孔洞处出现疲劳裂纹,从而增加了对疲劳现象的认识和对它的注意。      

力学学科的作用与力学知识的普及——《力学与现代生活》出版

力,在日常生活中无处不在。不管是有生命的人类和生物,还是无生命的结构和建筑,从宏观到微观,大自然都处在作用力与反作用力的统一体中。力是使物体发生形变或产生加速度的外因,它既可以造福于人类,也可以加祸于人类。有的生活、自然现象其机理一目了然,有的则较难理解。力学,就是研究力对物体的作用,它是研究机械运动普遍规律的科学,它是自然科学中运用定量分析工具——数学——最多最深的一门学科,也是一门最古老、最重要的学科。     

略谈热结构力学

热结构力学是研究工程结构受力、受热后的变形与应力的发生、发展和破坏规律,以及各种分析方法的学科。它是固体力学的一个重要分支。近二十多年来,由于高速飞机、宇航飞行器、导弹、火箭、潜艇和原子能发电站等现代科学技术的重大成就,以及它们的组成部分,如涡轮发动机、喷气发动机、火箭发动机、固体燃料发动机、原子反应堆等设计的飞速发展,有力地推动了热结构...     

自然灾害研究中几个观念问题的讨论

本文从人类生活环境系统的整体观角度讨论了自然灾害的两重性、关连性及人类圈之形成和生态环境保护问题。认为自然灾害从短时间尺度和小范围看是灾变, 从长时间尺度和大范围看是一种自调节、自平衡过程；自然灾害与人类社会存在着双向效应关系；自然灾害的关联性(群发共生现象)是由其同源性、链发性和韵律性决定的；人类圈是地球演化进入新阶段的产物, 它具有进行层次深、作用强度高、活动领域宽和通过信息实现调控的特点。建立上述观念, 对灾害研究、减轻灾害损失, 走可持续发展的道路, 都具有重要意义。     

多时标电力系统模型分岔现象的理论基础及其关系分析

本文讨论了多时标电力系统模型中的奇异诱导分岔和奇异霍普夫分岔的特点及其相互关系。第一，给出了奇异诱导分岔的定义并讨论了它在一类时间解耦电力系统DAE模型中的存在性：第二，扩展了SHB分岔理论的应用范围使之适用于一类和其本身慢性流型维数无关的电力系统ODE模型；第三。采用新的方法证明了SIB定理并以此解释电力系统DAE模型发生SIB分岔和ODE模型发生SHB分岔的关系。最后，讨论了以DAE描述的电力系统模型中SIB点的一些特点。     

On the motion stability of an airplane on a runway under wind loading

A nonlinear mathematical model is constructed for an airplane in high-speed plane-parallel motion along a runway when the airplane's weight exceeds slightly the lift of its wings in the presence of a cross wind. The airplane is considered a two-weight mechanical object. A system of second-order equations is obtained that describes the airplane's behavior. A system of three phase variables is suggested in which the dynamics of transverse motion is described by a set of three second-order equations. A stationary solution of this system is obtained. A stability criterion for the plane-parallel motion of the airplane is established using the Routh-Hurwitz criterion. Analysis of the data of other authors indicates that the mathematical model is adequate for some objects of aviation technology. Translated from Prikladnaya Mekhanika, Vol. 35, No. 10, pp. 101–107, October, 1999.     

APPLICATION OF COMPUTATIONAL FLUID DYNAMICS IN THE PLANNED DITCHING OF A TRANSPORT AIRPLANE

论述了边界元法、有限元法、光滑粒子水动力学法、有限体积法、工程算法与混合分析法在飞行器水上迫降中的应用和发展,总结了不同方法的优缺点,指明了未来的研究重点,为进一步开展水上迫降研究提供参考.     

腐蚀条件下飞机结构疲劳寿命评定技术的试验验证

一般环境下飞机结构疲劳寿命评定技术已相对成熟,而建立在模拟试验基础上的腐蚀条件下飞机结构疲劳寿命评定技术目前尚不完善.本文通过退役飞机全尺寸结构疲劳试验结果与对应的关键部位腐蚀条件下疲劳寿命评定结果的对比分析方法,验证腐蚀条件下飞机结构疲劳寿命评定方法,同时提出了用已服役多年飞机全尺寸结构疲劳试验结果修正地面停放腐蚀修正系数曲线及加速环境谱当量加速关系的方法.     

A coupling model for terrestrial processes in arid areas and its application

IntroductionItiswell-knownthatland-atmosphereinteractionexertsgreatinfluencesonglobalandregionalenvironment(Woodfool,Yih1994).Inordertodeterminethefluxesandtheparameterizationschemeattheland-atmosphereinterface,itisnecessaryforustoinvestigateterrestrialprocessesontypicalunderlyingsurface.Aridarea(includingextremelyarid,aridandsend-aridareas)ofsabillionklnZ,occupiesalmostonethirdofthelandsurface,mainlyinNorthAfrica,CentralAsia,AustraliaandNorthAInerica.Amongthemdesertcoversnearly6millionkl…     

CFD computations of NAL experimental airplane with rocket booster using overset unstructured grids

Flows around the NAL jet‐powered experimental airplane with a small rocket booster under the fuselage are computed by solving the Euler equations using the overset unstructured grid method. The main objective of the present study is to evaluate the effect of a small rocket booster, which accelerates the airplane to supersonic speed, on the aerodynamic performance of the airplane during the ascent flight and the booster separation. Two unstructured meshes, one for the airplane and one for the booster, overlap. For the accurate separation simulation, the two bodies are in contact at first, and then the booster mesh is contact mesh is moved relative to the airplane mesh to evaluate flow interactions between two bodies. Copyright © 2005 John Wiley & Sons, Ltd.     

OPERATIONAL MODAL ANALYSIS SCHEMES USING CORRELATION TECHNIQUE

For some large-scale engineering structures in operating conditions, modal parameters estimation must base itself on response-only data. This problem has received a considerable amount of attention in the past few years. It is well known that the cross-correlation function between the measured responses is a sum of complex exponential functions of the same form as the impulse response function of the original system. So this paper presents a time-domain operating modal identification global scheme and a frequency-domain scheme from output-only by coupling the cross-correlation function with conventional modal parameter estimation. The outlined techniques are applied to an airplane model to estimate modal parameters from response-only data.     

Testing methods for large aircraft

Some unique testing methods in connection with static-load application and associated data acquisition are described. The “free-flight” method of airplane static testing is covered as it applies to the current test program for the C-133 Cargomaster (300,000 lb gross weight). The loading and safety advantages of the “single-pressure concept” are discussed. Instrumentation provides for visual readout as well as IBM punch cards for records of deflection, cabin pressures, jack loads and up to a total of 2800 strain gage installations. Use of the “Electromec,” and safety methods for fuselages pressurized by air are discussed. Additional areas that are covered: hydrostatic-test methods and instrumentation; fail-safe development for pressurized cabins; and future of fatigue tests of a complete airplane.     

疲劳多裂纹问题研究进展

介绍了近十年来颇受关注的疲劳多裂纹(MFC)问题的研究．其研究的对象主要是长寿命承力结构，尤其是老龄飞机；目的是建立疲劳多裂纹问题裂纹扩展的计算模型和含疲劳多裂纹结构的失效准则．该研究为长寿命承力结构的疲劳可靠性评定奠定了基础．     

An sequential optimization and aeroelastic constraint transformation method for strength-aeroelastic comprehensive design

With the development of modern aircraft technology, aeroelasticity plays a more and more crucial role in aircraft structural design. However, low efficiency of present aeroelastic analysis and optimization methods makes it difficult to apply in engineering practice. This paper presents a sequential optimization and aeroelastic constraint transformation method (SOACTM) for comprehensive design of airplane wings with strength and aeroelastic constraints. Optimization with structural strength constraint and aeroelastic constraint is transformed into a serial of cycles of decoupled structural strength sub-optimizations and aeroelastic sub-optimizations based on sequential optimization strategy. In structural strength sub-optimization, structural strength constraint is translated along its normal direction to make optimal design point satisfying aeroelastic constraint. And the goal of aeroelastic sub-optimization is to find the translational distance of structural strength constraint. Aeroelastic constraint is transformed to equivalent structural strength constraint via above approach. In this way, number of aeroelastic analyses in SOACTM is less than that in traditional optimization method and total computational time decreases. SOACTM is verified based on two examples. Traditional optimization method is applied for the sake of validation. The results demonstrated the accuracy and efficiency of SOACTM for wing comprehensive optimization considering both structural strength and aeroelastic constraints.     

Designing random vibration tests

The paper provides information about two concepts of digital simulation of samples of the stationary Gaussian stochastic processes possessing multi-modal spectra. They have been applied in order to imitate dynamic loads arising on an airplane undergoing gusty flying conditions. Therefore the particular spectra typical for an airplane gust study were involved, reflecting also elastic properties of the flying vehicle. The presented details are devoted to the problem of solving the system of algebraic non-linear equations describing the desired linear filter. At this stage the given results can be also applied in studying earthquakes, modelling gusty winds for civil engineering and other purposes.