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1.
首先选用对噪声抑制效果较好的Hv估计方法,然后引入对泄露有明显抑制效果的全相位FFT频谱分析方法,构成全相位Hv频响函数估计方法,改善了频响函数估计效果,减小了频响估计误差对MIMO随机振动试验控制效果的影响.最后在钢质悬臂梁上做两输入两输的Hv估计和全相位Hv估计的对比试验以及两种估计结果在MIMO随机振动试验控制的应用效果,试验结果验证了全相位Hv频响函数估计对改善了随机振动试验控制效果的有效性.  相似文献   

2.
车辆非平稳响应的瞬时空间频谱分析   总被引:3,自引:2,他引:1  
本文提出了解决车辆非平稳随机振动问题的“瞬态空间频响函数”法 ,导出了车辆非匀速行驶时的时 -空频率关系和系统的瞬态空间频响函数 ,在此基础上结合实例分析了车辆非平稳响应的瞬时功率谱 ,并与其他方法进行了比较。该方法也可适用于非线性非平稳车辆随机振动研究 ,对车辆非平稳动态载荷研究有一定参考价值。  相似文献   

3.
导电梁在磁场中的磁弹性随机振动   总被引:1,自引:1,他引:1  
根据磁弹性基本理论和连续体的随机振动理论,得到了在外加磁场中通有随机电流的梁的磁弹性随机振动方程。给出了导电梁在耦合场中的洛伦兹力及力矩,并将洛沦兹力的耦合项假设为梁的一种阻尼,另一部分假设为随机分布载荷,对梁的位移响应进行了分析。以简支梁为例,分别得到了外加磁场中通入平稳和非平稳随机电流时简支梁的位移响应的均值、自相关函数、功率谱密度函数等数字特征。最后以一个通有理想白噪声平稳随机电流的简支梁为实际算例,对其位移响应的功率谱密度函数进行了计算。图形形状的改变表明了耦合项对梁的功率谱密度函数的影响,据此可知通过控制随机电流和磁场可以达到控制梁的随机振动的目的。  相似文献   

4.
王平  李晓靓  刘强 《振动与冲击》2009,28(1):138-142
根据磁弹性基本理论和连续体的随机振动理论,得到了在外加磁场中通有随机电流的导电薄板的磁弹性随机振动方程。给出了导电薄板在耦合场中的洛伦兹力及力矩,并将洛伦兹力的耦合项假设为薄板一种阻尼,另一部分假设为随机分布载荷,对板的随机位移响应进行了分析。以四边简支矩形薄板为例,分别得到了外加磁场中通入平稳和非平稳随机电流时导电板的随机位移响应的均值、自相关函数、功率谱密度函数等数字特征。  相似文献   

5.
本文评述了近几年来在国外发较快的几种非线性系统随机振动分析方法.重点是具有较大非线性的系统的方法,如FPK法,矩闭合法和函数级数法.  相似文献   

6.
超高斯伪随机振动激励信号的生成技术   总被引:9,自引:2,他引:9  
振动激发试验和振动模拟试验的最新发展都需要产生超高斯分布的随机振动激励信号。然而,目前基于功率谱均衡的数字式随机振动控制系统只能产生高斯分布的随机振动激励信号。研究具有指定功率谱密度分布的超高斯伪随机振动激励信号的生成技术,从而使现有的数字式随机振动控制系统可以同时具有频域和幅值域的双域控制及均衡能力。仿真和试验结果验证了该方法的正确性和有效性。  相似文献   

7.
中国振动工程学会随机振动分会于1991年8月22日~23日在山东省泰安市召开了“全国第三届随机振动学术交流会”。参加会议的代表共71名,其中青年人约占30%,他们活跃在随机振动科学技术领域,成为一支重要的生力军。交流内容包括随机振动理论,计算方法,信号处理技术,随机振动的控制,系统识别,以及  相似文献   

8.
陈新华  杨绪强  李国星 《硅谷》2010,(14):173-173
多维随机振动试验是一种比单维随机振动试验更加接近真实环境的试验手段,主要描述多维随机振动试验的数学模型,以及它在例行环境振动试验中应用的优越性与前景。  相似文献   

9.
随机振动条件下SMT焊点半经验疲劳寿命累积模型   总被引:1,自引:3,他引:1  
郭强  赵玫  孟光 《振动与冲击》2005,24(2):24-26,36
研究了SMT焊点在随机振动条件下引起的振动疲劳情况,给出了SMT焊点半经验随机振动疲劳寿命累积模型,并通过对某SMT电路板进行随机振动疲劳测试,验证了模型的正确性。  相似文献   

10.
利用高灵敏度速度传感器,对上海光源实验大厅地基的随机振动进行了多点同步测量。数据分析结果表明上海光源实验大厅地基随机振动幅值具有周期变化的规律,且在低频区2 Hz~10 Hz具有较好的隔振效果。首次在上海光源大厅内进行随机振动中传递的相干规律的测试,测试表明在上海光源实验大厅中,距离为10 m的测试点在2.5 Hz以内的随机振动的互相关大于0.9;距离超过10 m时,两点随机偏差大于50 nm,超过随机振动RMS振幅的20%。随机振动传递规律的分析,对同步辐射光学元件的隔振设计有一定的指导作用。  相似文献   

11.
Abstract: A ‘Go’ or ‘No Go’ assessment is a safety requirement for quick and robust estimation of the condition of gearboxes used in helicopters and other critical machines. A range of vibration‐based condition indicators (CIs) has been developed to meet this requirement. CIs are compared automatically with pre‐set threshold values representing a healthy system, so that the health of the gearbox can be assessed and diagnosis made where necessary. The use of kurtosis of the residual signal of the measured vibration data, computed as part of the ‘FM4’ method, is widespread, because it is accepted as a good and reliable indicator. However, it has been observed in some cases that FM4 may not show a continually increasing trend with the propagation of a fault. This behaviour may lead to improper assessment of the severity of the fault. Hence, a new CI, based on the deviation in the normal probability density function (PDF) of the measured vibration data, is suggested which demonstrates an increasing trend that is more robustly and monotonically correlated with the fault propagation.  相似文献   

12.
运用概率统计的方法,对机械结构在阶跃干摩擦函数及二阶线性弹性函数作用下的振动数学模型进行分析,并给出汽车对应二阶线性弹性力的位移和加速度输出均方差,以便更合理地选择对汽车振动产生重要影响的某些参变量.  相似文献   

13.
In this article, the exact probability density function for a nonlinear exponential functionally graded orthotropic plate under lateral random excitation is investigated. After that, a study on the probability density function (PDF) is done to examine the dynamic instability and bifurcation. Using nondimensional parameters, the results are justified for a wide range of plates. The outcomes are studied with respect to the variation of both mean value of lateral loads and in-plane forces. The famous Monte Carlo simulation is employed to validate the obtained analytical PDFs. An analogical study is done between the behaviors of homogenous plates with their corresponding functionally graded material ones. Finally, it is shown how the exponential profile functionally graded orthotropic material can affect the quality of instability and bifurcation.  相似文献   

14.
针对电动振动台和数字式电动振动试验系统使用中的交越频率的定义及其推理过程加以阐述,探讨了影响电动振动台和数字式振动试验系统正确使用的因素及相关技术问题,同时针对检定规程中所规定的一些检定方法提出了值得商榷的看法,并给出相应的计算公式,供参考使用。  相似文献   

15.
A method of estimating the probability density function and cumulative distribution function when only the ordinary or central moments of the distribution are known is examined. The technique is used in conjunction with previous work which yields the ordinary moments of time to first passage failure to obtain accurate estimates of the failure probability for two representative oscillators. The results are then compared to those obtained by a nearly exact numerical scheme.  相似文献   

16.
《TEST》1982,33(2):47-63
This paper gives a formalization of the relation between the Debreu’s value function and the Von Neumann’s utility function, with a generalization of this result for their respective vectorial functions. Finally the problem of incorporating complementary information is consisdered.
  相似文献   

17.
Metal disks of different size and density were placed at the bottom of a bed of monodisperse granular material. The system was vibrated sinusoidally in the vertical direction. It was observed that, if the angular acceleration of the shaking was slightly greater than that of gravity, the metal disks rose to the top of the bed. This result has been known for over sixty years, but a basic understanding of the mechanism responsible for the rise of the disks is still a subject of debate. Our experiments and theoretical model show that the ascent speed of the disk is proportional to the square root of the disk density, approximately proportional to the disk size, and is a function of the disk's depth in the bed. We also investigated the speed of ascent of the disk as a function of the shaking frequency, f s . We found that the effective friction or drag coefficient, β, between the disk and the granular bed, is proportional to a functional form of the frequency: β∝ (f s f c )−4, where f c is the critical shaking frequency for the disk to start moving through the bed. We discuss how such a dependency may arise. Received: 28 August 2000  相似文献   

18.
针对某高分辨率空间相机结构随机振动加速度响应大的问题,对空间相机支撑结构进行了优化设计。(1)建立了基于随机振动响应分析的数学模型,推导了随机振动均方根响应表达式;(2)基于三点定位原理和双脚架柔性结构原理设计了相机支撑结构,以相机安装点RMS值最小为目标,基频作为约束,建立了相机支撑结构随机响应优化模型,对支撑结构柔性环节位置进行了尺寸优化设计,采用MSC.PatranNastran有限元分析软件对优化处理后的支撑结构进行了工程分析,相机安装点随机响应RMS值最大19.6 grms;(3)对相机支撑结构进行了随机振动试试验。结果显示:有限元分析结果与试验测量数据符合的较好,最大相对误差为8.2%,所设计的空间相机支撑结构满足空间相机使用要求,验证了所采用优化方法的可行性。  相似文献   

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