变时基采样锤击法高精度传递函数的估计  

High Precision Transfer Function Estimation for Hammering Test Using Variable Time-based Sampling Technique

作　　者：杨陈[1] 高建勇[1] 王茂华 YANG Chen;GAO Jianyong;WANG Maohua(Earthquake Engineering Research Center,China Institute of Water Resources and Hydropower Research,Beijing 100048,China)

机构地区：[1]中国水利水电科学研究院工程抗震研究中心,北京100048

出　　处：《噪声与振动控制》2023年第2期292-297,共6页Noise and Vibration Control

基　　金：中国水利水电科学研究院基本科研业务费专项项目-混凝土坝振动台模型试验技术研究(抗基本科研01882101)。

摘　　要：传统锤击法试验模态分析时面临着高采样率带来噪声干扰、频率分辨率不足的问题,应怀樵等人发明了对力锤信号使用高采样频率、对响应信号采用较低采样频率的变时基采样技术(VTB),一定程度上改善了测试结果,但仍然存在变时基采样设置不灵活,传递函数在固有频率半功率带宽里分辨率不足、精度不高的问题。基于连续傅里叶谱变换、Chirp-z变换方法,提出一种新的锤击法变时基传递函数高精度估计方法,可很好地解决传统变时基技术存在的问题。并采用数值模型、悬臂梁现场测试进行验证,结果表明所提出的算法优于传统等时间间隔采样技术,比传统变时基技术更为灵活,得到的传递函数质量较好,使得变时基采样技术具有较高的识别精度,可解决高采样率与频率分辨率不足的问题。The problem of noise interference and insufficient frequency resolution due to high sampling frequency are often encountered in traditional hammering test.In order to solve the problem,YING Huaiqiao et al.invented the variable time based(VTB)sampling technology,which adopts a high frequency sampling for the impact force signal and a low frequency sampling for the response signal.This method can improve the test results to a certain extent.However,there are still some problems,such as inflexible setting of VTB sampling frequency,insufficient resolution and low accuracy of transfer function in the semi-power bandwidth.Based on continuous Fourier transform and Chirp-z transform(CZT),this paper proposes a new high-precision VTB transfer function estimation method for the hammering testing,which can solve the problems existing in traditional VTB technology.The numerical model and cantilever beam test are used to verify the new method.The results show that the proposed method outperforms the traditional equally-spaced time interval sampling technique,it is more flexible than the traditional VTB technique.With this method,one can obtain better transfer functions and higher modal parameter identification accuracy,and solve the problems of high sampling rate and insufficient frequency resolution.

关 键 词：振动与波 锤击法模态分析 变时基技术 连续傅里叶谱变换 CHIRP-Z变换 传递函数 

分 类 号：TK417.127[动力工程及工程热物理—动力机械及工程]