机械系统动力学特性的综合分析及其工程应用

发布时间：2018-06-04 17:14

本文选题：实验模态分析 + 工作模态分析　；参考：《太原理工大学》2013年博士论文

【摘要】：随着计算机技术、网络技术、通信技术等为代表的信息技术广泛应用于机械工程的各个领域,使得机电产品发生了重大变化。当然,这些变化也包括为产品的设计提供支撑的机械学科理论与应用技术的发展。近年来,上述研究取得了一系列重要成果,这些成果在机电产品的创新开发与设计中发挥重要作用。根据系统辨识与结构动力学的基本原理以及相应的试验技术发展起来的实验模态分析(EMA)与工作模态分析(OMA)技术取得长足的发展,从而帮助设计人员根据辨识模型更好地领悟对象机理,并将这些机理应用于产品设计,有力地促进产品的原创性开发与设计,并不断地扩大它的应用领域。近年来工作模态分析在机械系统与结构的动态分析与设计以及运行监测与故障诊断等方面获得广泛应用,在应用中也暴露出这些方法存在的问题与缺点,必须解决这些问题才能使这种方法得到有效的工业应用。本文研究适用于大型机械装备与结构的工作模态分析以及消除现有工作模态分析某些缺点的方法。研究的目的是：减少模态试验时间；允许最大限度地利用试验数据；减少分析的复杂性,可以较容易地处理数据；适用于大型机械结构模态试验存在的大量的传感器、大阻尼、带噪声数据、短的数据记录等情况；提高模态参数估计精度。为了达到上述目的,作者从模态试验与模态参数估计方法两方面入手解决工作模态分析的有关问题,取得了重要成果,并成功应用于大型工业装备。本文回顾了模态分析的基本理论与方法,包括实验模态分析(EMA)、工作模态分析(OMA)以及有外加输入的模态分析方法(OMAX)。在OMAX架构中讨论了确定性贡献的频响函数估计和随机贡献的正功率谱估计。在此基础上指出这些方法的局限与缺点,作为展开本文研究的背景。提出了一种基于循环倒谱的工作模态分析方法。该方法解除了输入信号为白噪声的假设,提高了模态参数的辨识精度。使用循环平稳信号的处理技术来分离响应中由于循环平稳输入信号引起的成分,非常有效地将多输入多输出(MIMO)系统降低为单输入多输出(SIMO)系统,在倒谱域进行曲线拟合,将输入和传递函数分离开,识别出系统的谐振和反谐振,进而得到系统的传递函数。通过钢梁试验对该方法进行验证,并与EMA分析结果进行比较。在这个试验中,精确估计了谐振频率和振型,并且通过增加平均次数来降低估计的不精确性。为了解决当输入激励不是白噪声时OMA过程中尺度丢失的问题,本文提出一种恢复模态振型之间的相对比例(尺度)和所有模态振型的全局比例(尺度)的简单方法,该方法建立在循环倒谱的基础之上。这种方法包括通过响应谱识别谐振与反谐振,并用以有限元模型。然后,通过有限元模型得到等效曲线,从而恢复频率响应函数的尺度。针对大型机械结构常常出现的由于工作或环境激励的频带较窄,致使工作模态过程中丢失模态以及计算速度慢等问题,提出准工作模态分析方法,即在大结构的部分区域结合使用可测量激励力(类似于实验模态分析)的外加局部辅助激励输入的工作模态分析方法,并提出了适合于准工作模态的基于参考的确定性随机子空间混合辨识算法,提高了模态辨识的精度和速度。为验证基于参考的确定性随机的准工作模态分析方法,将其应用于工业振动筛工作模态的综合分析,精确地辨识了振动筛的模态参数,得到很好的效果,证明了该方法的鲁棒性与可靠性。
[Abstract]:With the development of computer technology , network technology , communication technology and so on , the information technology is widely used in various fields of mechanical engineering . These changes also include the development of mechanical subject theory and application technology which support the design of products .

In recent years , the working modal analysis has been widely used in the dynamic analysis and design of mechanical systems and structures , as well as operation monitoring and fault diagnosis .
allowing maximum utilization of test data ;
the complexity of the analysis is reduced and data can be processed more easily ;
It is suitable for large number of sensors , large damping , noisy data and short data records .
In order to achieve the above - mentioned object , the author starts to solve the problem of working modal analysis from two aspects of modal test and modal parameter estimation , and has achieved important results and successfully applied to large - scale industrial equipment .

This paper reviews the basic theories and methods of modal analysis , including the experimental modal analysis ( EMA ) , the working modal analysis ( OMA ) and the modal analysis method ( OMAX ) with external input . In the OMAX architecture , we discuss the estimation of the frequency response function of the deterministic contribution and the positive power spectral estimation of the random contribution . On the basis of this , the limitations and disadvantages of these methods are pointed out as the background of the research .

This paper presents a working modal analysis method based on cyclic cepstrum . The method eliminates the assumption that input signal is white noise and improves the accuracy of modal parameter identification . In this experiment , multi - input multiple - output ( MIMO ) system is reduced to single - input multiple - output ( SIMO ) system . In this experiment , multiple - input multiple - output ( MIMO ) systems are effectively reduced to single - input multiple - output ( SIMO ) systems . In this experiment , the resonance and inverse resonance of the system are identified and compared with EMA analysis results . In this experiment , the resonance frequency and mode are accurately estimated , and the estimation accuracy is reduced by increasing the average number of times .

In order to solve the problem of scale loss in the OMA process when the input excitation is not white noise , this paper proposes a simple method of restoring the relative proportion ( scale ) between modal modes and the global scale ( scale ) of all modes modes . The method is based on the cyclic cepstrum . The method includes identifying the resonance and the inverse resonance by response spectrum , and using the finite element model . Then , the equivalent curve is obtained by the finite element model , so that the scale of the frequency response function is restored .

A quasi - working modal analysis method is proposed for large - scale mechanical structures due to the narrow frequency band excited by operation or environment , which leads to the loss of modes and the slow computation speed in the process of working modes .

In order to validate the quasi - working modal analysis method based on the reference - based deterministic stochastic , the modal parameters of the vibrating screen are accurately identified , the modal parameters of the vibrating screen are accurately identified , and the robustness and reliability of the method are proved .
【学位授予单位】：太原理工大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TH113

【相似文献】