结构试验机的神经网络内模自适应跟踪控制系统

针对结构试验系统的非线性和不确定性特性，研究了一种基于神经网络的非线性内模自适应加载控制方法。引入的神经网络内模可跟踪学习对象的时变动力学，控制器的设计较少依赖于对象的先验知识，控制参数的调整是基于被控过程的测量信息，利用导出的神经网络算法来实现的。实验结果证明该系统具有良好的控制效果。     

研究岩石破裂等弱化行为的力－位移组合控制方法

本文介绍了一种用力和位移的线性组合控制岩石试验的新方法。该方法已在一台自制的伺服实验系统上和一台MTS实验系统上得到了实现。用这种方法能够简便地求出通常难以求出的具有Ⅱ类特性岩石的全应力-应变曲线,而且能够变化出如广义应力松驰等其它实验类型,从而能够对时间依赖性进行深入的研究。由于其易于采用的特点,它在研究岩石破裂乃至摩擦等弱化过程方面有着广泛的应用前景。     

A Review of External Pressure Testing Techniques for Shells including a Novel Volume-Control Method

A review of conventional testing methods for applying external hydrostatic pressure to buckling-critical shells is presented. A new “volume-control” pressure testing method, aimed at preventing catastrophic specimen failures and improving control of specimen deformation near the critical load, is also introduced. The implementation of conventional and volume-control systems in an experimental program involving the destructive pressure testing of ring-stiffened cylinders is described. The volume control method was found to improve control of the specimen deformations, especially near the critical load, and catastrophic failures observed while using a conventional setup were avoided. The quasi-static tracking of post-collapse load-deformation relationships for snap-through buckling behaviour was possible while using a volume-control system, but precise control of dynamic shell deformations during buckling was not achieved for specimens failing with large buckling lobes. Expressions for estimating the available control over specimen deformations for pressure testing systems are presented.     

某型导弹惯性控制系统测试

某型惯性控制系统是该导弹惯性制导系统的重要组成部分。用静止导航试验法来测试惯性导航系统性能,是一种简便易行的方法。为了高效地对惯性控制系统进行维修测试,以静止导航试验法为基础,进一步提出了在线测试和离线测试两种测试方法。介绍了某型导弹惯性控制系统自动测试设备的总体设计方案及软件、硬件实现方法,并研制出了相应的测试设备。该设备采用虚拟仪器技术,主要由测控计算机系统、信号控制调理模块和电源组成,主要编程软件为LabWindows CVI8.0。实际工程测试表明：用这种测试方法和设备,能够较详尽地测试出惯性控制系统的性能参数,较准确地进行产品的故障定位,大幅度提高了产品的测试和维修效率,在功能、精度以及实时性等方面都达到了预期的目标。     

High-speed stochastic fatigue testing

Good stochastic fatigue tests are difficult to perform. One of the major reasons is that ordinary servohydraulic loading systems realize the prescribed load history accurately at very low testing speeds only. If the speeds used for constant amplitude testing are applied to stochastic fatigue testing, quite unacceptable errors are introduced. Usually this problem is solved by running the tests at very low speeds and by editing the load history in order to reduce the duration of the test. In this paper a new method for control of stochastic fatigue tests is proposed. It is based on letting the analog control device remain as the basic control mechanism in the system, but distorting the input signal by computer in order to minimize the errors of the load history extremes. The principle proves to be very efficient to reduce all kinds of system errors and has shown to be able to increase the allowable speed by a factor from 10 to 30.     

模糊—神经网络控制算法及其在离心力—振动复合环境试验系统中的应用

针对离心－振动复合环境试验系统所存在的耦合性、非线性和不确定性提出了一种模糊－神经网络控制算法,利用被控对象输入输出信息离线、在线相结合学习系统的动态特性,对时变、非线性系统进行跟踪控制,并研究了该算法在系统中的实现方法。实现表明了控制系统具有良好的跟踪能力。该算法也适用于快速变化这类系统的实时控制。     

振动轮式硅微陀螺仪检测轴的闭环特性

研究了振动轮式硅微陀螺仪敏感结构的谐振特性,重点进行了检测轴的闭环控制系统分析和测试。通过对不同气压条件下检测轴谐振特性的研究及驱动轴和检测轴谐振频率匹配的试验,分析了静电力反馈控制系统中的变刚度问题,进行了硅微陀螺仪检测轴的闭环控制系统设计,给出了检测轴闭环控制系统的原理框图和传递函数,同时分析了闭环条件下驱动轴回路和检测轴回路各部分的相位关系以及正交分量的消除方法。试验结果表明闲环控制提高了硅微陀螺仪的精度指标。     

基于贝叶斯方法的模态参数识别的不确定度分析

振动模态分析和模态参数识别是动态测试的一个重要研究方向。模态参数在模型的修正、响应的预测、系统的健康检测及控制等方面有着重要的作用。但动态测试的不确定度分析,尤其是模态参数的不确定度的研究还十分缺乏。本文主要基于贝叶斯方法,通过傅立叶变换(FFT)建立时域数据和频域数据之间的对应关系。根据共振频带内的多个模态的响应数据得到相对应的模态参数,优化得到模态参数的最佳估计值,评定模态参数识别的不确定度。在固支梁的模态实验中,加速度传感器采集环境激励中的振动数据,运用贝叶斯法进行处理得到模态参数的最佳估计值。在此基础上,通过模态参数的最佳估计值,以及仪器的检定报告数据,结合合成不确度分析方法,系统分析了模态参数识别的不确定度。     

Mechanical testing using direct control of the inelastic strain rate

A methodology is described for carrying out mechanical tests under direct control of the inelastic strain rate. The method depends on the use of a servohydraulic testing machine and suitable electronic-control circuitry. The technique permits the use of abrupt changes of inelastic strain rate as well as maintenance of constant values of inelastic strain rate. The application of the method to several modes of testing is described.     

斜拉索振动的模糊半主动控制研究

考虑拉索垂度及抗弯刚度的影响,得出了索-阻尼器系统振动偏微分方程;用中心差分法将偏微分方程在空间内离散,导出了系统的面内振动常微分方程组;提出了使用MR阻尼器(Magnetorheological Damper)作为控制设备,模糊集为基础的半主动控制算法,并运用提出的算法对索-阻尼器系统进行了振动控制分析。本文方法的优势在于算法自身的鲁棒性、处理非线性问题的能力强和不需要结构的精确数学模型,算法需要的输入变量少,可以解决实际工程中斜拉索的振动响应信息难以测量的困难。模糊算法的输出直接控制MR阻尼器的输入电压。与LQR-Clipped算法不同,MR阻尼器的输入电压可以是零与最大值之间的任意值。本文以实际斜拉桥拉索为例,分析了拉索的振动控制效果,结果表明本文提出的模糊半主动控制算法,使MR阻尼器的功能得到了更好的发挥,比MR被动控制效果好,且可以减小控制力。     

大当量浅埋地下爆炸抛掷成坑效应的缩比模拟实验装置

针对当前地下爆炸物理模型实验无法模拟大当量地下爆炸抛掷弹坑和疏松鼓包现象的难题,基于相似理论,采用地下爆炸效应真空室模型实验方法,研制了考虑重力影响的大当量地下爆炸效应模拟实验装置。整套装置由容器罐体、快开门密闭机构、爆源系统、真空泵组、量测控制系统等组成,提出的新型爆源模拟装置可以实现精确起爆控制。该装置可模拟0.1~100 kt TNT、埋深20~400 m范围内不同比尺的地下核爆炸成坑和隆起实验,同时也能够模拟不同装药配置方案、不同地质条件下的大当量地下浅埋化爆抛掷实验。典型的核爆抛掷成坑模型实验结果表明,装置实验参数精确可调,实验过程可控,实验结果可信,为钻地核武器地下爆炸毁伤效应分析和大型工程爆破效果预测预报提供了实验室模拟和科学研究设备,填补了爆炸离心机无法模拟大当量地下爆炸抛掷成坑效应的空白。

     

Development of the Strategy of Active Control of Instability Waves in Unexcited Turbulent Jets

The possibility of controlling instability waves in the mixing layer of a subsonic unexcited jet is studied. These waves can be noise sources in both free jets and jets as parts of configurations. In the study the method of experimental diagnostics of the instability waves in the near field of a jet using an azimuthal multimicrophone array is realized. The data on the near field fluctuations are used for testing the control strategy proposed by the authors. The strategy consists in narrowband sliding filtration of the original signal and the formation of a narrowband controlling action on the basis of the linear principle of signal superposition. The results of the study represent the next step toward the realization of an active control system suppressing natural instability waves in turbulent jets.     

PIV图像粒子像斑定位偏差综合评估试验及其测速误差评估

本文针对ＰＩＶ技术的直接测量法中图像的可读性和可测性，讨论了从模拟图像到数字图像，最后到粒子像斑中心位置的确定过程中的误差规律；并提出了一种称之为粒子像斑定位偏差综合评估的试验方法。     

航天器力限振动试验条件设计研究

航天器在研制过程中要经过一系列地面力学验证试验, 但在传统加速度控制振动试验中, 受试航天器或其部组件和试验台的连接机械阻抗与真实飞行状态存在很大差异, 如果仅采用加速度条件进行控制可能产生严重的"过试验" 现象. 美国早在20 世纪60 年代就已认识到这一问题, 但直到最近十几年才通过力限振动试验的办法加以解决. 力限振动试验技术分为力限振动试验条件设计技术和力限振动试验控制技术, 其中试验条件设计是开展振动试验的基础和依据. 本文对国内外力限振动试验技术的发展历程和重要成果进行了简述, 并结合我国力限振动试验技术的现状, 对力限振动试验技术在我国的应用和发展, 以及有待进一步研究的问题进行了展望.      

螺桨盘转子轴头动刚度实验测量方法及技术处理

在螺桨盘转子系统的颤振涡动研究中,系统的安装刚度对转子的颤振涡动失稳有着重要的作用.对于飞机发动机,实际安装情况十分复杂,发动机短舱.安装节、机翼等对螺桨盘转子的运动均有影响.所以,在颤振涡动研究中,必须考虑轴头的动刚度.轴头的动刚度是通过动柔度转换而来的,而在动柔度的实验测量中必须解决几个技术问题,首先是提高信噪比.其次是消除工艺夹具带来的附加质量和附加转动惯量的影响,从而提高动刚度系数的测量精度.本文通过对模型转子以及某实际桨轴发动机转子轴头动刚度系数的测量及处理,阐述轴头动刚度矩阵的测量方法,以及有关技术问题的处理过程.     

小波滤波在基桩完整性测试系统中的应用研究

在小波分析基本理论和多分辨率逼近算法的基础上,本文给出了正交小波的构造方法,并用其产生镜像滤波器。针对基桩完整性检测过程中出现的一些问题,提出了将小波滤波用于基桩完整性检测系统的方法。用小波滤波对实际工程基桩的测试信号进行处理,使基桩完整性检测的准确性和可靠性得到提高。     

用振动试验方法测定羽毛球拍杆的刚度

将羽毛球拍杆简化为单自由度弹簧质量系统,用振动试验方法测出系统的固有频率,用于计算羽毛球拍杆的抗弯刚度,并以此作为评定羽毛球拍杆软硬度的指标. 振动试验方法方便、准确,可用于代替现行弹性测试法,作为测定羽毛球拍杆软硬度的标准.     

某型飞机双卫星定位校正系统精度测试

针对某型飞机双卫星定位校正系统的精度指标评定问题，讨论了精度指标的评定方法，研制了机载导航精度测试系统，并进行了试飞数据的采集和分析处理。结果表明，研制的机载导航精度测试系统是有效的，提出的CEP误差计算方法是可行的。     

Digital control for material testing

As a result of proposed changes in the standard specifications for performing the conventional tension test and evaluating the data obtained, a semiautomatic testing machine has been developed by incorporating a digital system to provide control of load, strain rate or stroke. Because the digital control is also a data processor, additional design information can be obtained during the test that would be valuable for designers, for quality control and for specialty sales. Additional features of the automated equipment include reduced testing costs, increased reliability and accuracy, uniformity, rapid data evaluation and print-out, and modular construction. This paper describes the areas in material tension testing that would benefit by using automated procedures. In addition, a system is proposed that incorporates the manufacturing and research requirements for automated of the tension test. Modifications and additions to present equipment are described to show how this equipment can be automated without introducing drastic changes that adversely affect testing reliability and economical operation.     

A high-strain biaxial-testing rig for thin-walled tubes under axial load and pressure

It is well know that high-strain biaxial testing with axial force and pressure on thin-walled tubes can be interesting from several points of view: capability of testing over the whole range of strain or stress ratios, great versatility of testing. and because of the physical system, the measured strains and stresses are principal. Nevertheless, there are few experimental-biaxial-fatique data due to the complexity of the testing equipment involved. In this paper, an experimental testing rig capable of subjecting thin-walled tubes to combined dynamic loadings in tension-compression with torsion and tension-compression with internal-external pressure is presented. The following components are described: the mechanical and hydraulic system, servohydraulic control, specimen configuration, strain-measuring equipment and data-acquisition system. The computation of stresses and strains, as well as examples of data acquisition, are also shown.