水工结构模态参数识别的数值模拟
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摘要
结构模态参数识别是对结构施加激励,采集结构上关键点的响应,分析激励和响应间传递函数以提取出结构本身固有频率、阻尼比、振型等模态参数。当前,模态参数识别方法均是基于线性系统推导建立的,当结构存在裂缝等具有非线性特性时,仍旧用基于线性识别方法求解的结果具有多大的可信度则难以确定,这也是当前线性系统参数识别方法的一个不足。本文分别对线性和非线性数值结构模型进行激励并获取响应数据,各自用单模态和多模态识别方法进行参数识别,分析结果发现,当前模态参数识别方法对线性结构具有较高的精度,但对非线性结构的适用性则有待进一步提高,随着对非线性结构激励的增大,识别结果越接近弱化线性结构近似特征值分析结果,但均不大于对应线性结构特征值分析理论值。
Modal parameter identification describes the process that imposing an excitation to the structure,making response acquisition of key points and calculating the frequencyresponse function between excitationand response,then extracting the natural frequency,damping ratio and modes of the structure. Nowadays,modal parameter identification is established based on the deduction oflinear system. However,when structure has some cracks and becomes nonlinear,it's uncertain to measure the accuracy of the results. This isalso one drawback of the current modal parameter identification of linear system. In contrast,this papergives excitation to the linear and nonlinear numerical structure model,and then calculates their modal parameter both using singlemode and multimodal method. The results show us that the current modal parameteridentification method has high precision for linear system and its adaptability for nonlinear structure systems should be improved. With the increasing of the nonlinear excitation,the results become much closerto the results of weaken linear structure's eigenvalue analysis,and not bigger than the corresponding theoretical results of linear structure's eigenvalue analysis.
Modal parameter identification describes the process that imposing an excitation to the structure,making response acquisition of key points and calculating the frequencyresponse function between excitationand response,then extracting the natural frequency,damping ratio and modes of the structure. Nowadays,modal parameter identification is established based on the deduction oflinear system. However,when structure has some cracks and becomes nonlinear,it's uncertain to measure the accuracy of the results. This isalso one drawback of the current modal parameter identification of linear system. In contrast,this papergives excitation to the linear and nonlinear numerical structure model,and then calculates their modal parameter both using singlemode and multimodal method. The results show us that the current modal parameteridentification method has high precision for linear system and its adaptability for nonlinear structure systems should be improved. With the increasing of the nonlinear excitation,the results become much closerto the results of weaken linear structure's eigenvalue analysis,and not bigger than the corresponding theoretical results of linear structure's eigenvalue analysis.
引文
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[2]刘晶波,杜修力.结构动力学[M].北京:机械工业出版社,2012.
[3]李德葆,陆秋海.实验模态分析及其应用[M].北京:科学出版社,2001.
[4]王济,胡晓.MATLAB在振动信号处理中的应用[M].北京:中国水利水电出版社,2005.
[5]刘进明,应怀樵.FFT谱连续细化分析的富里叶变换法[J].振动工程学报,1995,8(2):162-166.
[6]左鹤声,彭玉莺.振动试验模态分析[M].北京:中国铁道出版社,1995.
[7]傅志方.振动模态分析与参数辨识[M].北京:机械工业出版社,1990.
[8]曹树谦,张文德,萧龙翔.振动结构模态分析:理论、实验与应用[M].天津:天津大学出版社,2001.
[9]王小刚,徐侠.运用Levy法进行模态参数识别的一种程序[J].机械强度,1988,10(1):18-24.
[10]李臣,马爱军,冯雪梅.一种高效的频域模态参数识别法[J].振动与冲击,2004,23(3):130-134.
[11]黄方林,何旭辉,陈政清.识别结构模态阻尼比的一种新方法[J].土木工程学报,2002,35(6):22-25,33.
[12]刘章军,曾波,周宜红,等.地震动过程的概率模型及在重力坝抗震可靠度分析中的应用[J].水利学报,2014,45(9):1066-1074.
[13]胡少伟,米正祥,陆俊,等.混凝土断裂过程区能量耗散值研究[J].水利学报,2012,43(S1):145-152.
[14]李爽,王正中,高兰兰.考虑混凝土衬砌板与冻土接触非线性的渠道冻胀数值模拟[J].水利学报,2014,45(4):497-503.
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