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考虑频响函数混叠误差的阻尼比识别效果研究

Study on the effect of damping ratio identification considering frequency response function aliasing error

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通过实测频响函数识别阻尼比时,识别准确性受到频谱混叠现象的影响,因此建立了考虑频响函数混叠误差的阻尼比识别有效性判断方法.首先,根据傅里叶变换原理进行理论推导,证明了采样频率不足时频响函数会发生混叠现象;然后,根据频响函数混叠原理和模态叠加原理,建立了多 自由度结构的基准频响混叠误差拟合公式,进而给出考虑频响函数混叠误差的阻尼比识别结果有效性判断的步骤.通过对两自由度理论频响函数模型设置不同的等效柔度比和固有频率比,表明其对两阶模态计算频响混叠误差有显著影响;通过对比四层框架结构基准模型的响应在设置不同采样频率时对阻尼比的识别结果,验证了所提方法的可行性.
When the damping ratio is identified by the measured frequency response function,the accuracy of the damping ratio identification is affected by the spectrum aliasing phenomenon.Therefore,a method forjud-ging the effectiveness of the damping ratio identification considering the aliasing error of the frequency re-sponse function is established.Firstly,theoretical derivation is conducted according to the principle of Fourier transform,and it is demonstrated that the frequency response function will experience overlap when the sam-pling frequency is insufficient.Then,the fitting formula of the reference frequency response aliasing error of the multi-degree-of-freedom structure is established according to the frequency response function aliasing prin-ciple and the modal superposition principle.Subsequently,the implementation steps forjudging the effective-ness of the damping ratio identification results are formed,taking into consideration the frequency response function aliasing error.By setting different equivalent flexibility ratios and natural frequency ratios for the two-degree-of-freedom theoretical frequency response function model,it is shown that they have significant influ-ence on the frequency response aliasing error of the two-order modal calculation.By comparing the identifica-tion results of the damping ratio with the response of the four-story frame structure benchmark model at different sampling frequencies,the feasibility of the proposed method is verified.

sampling frequencyspectral aliasingfrequency response functiondamping ratio identificationFourier transform

曲春绪、屠桂凯、高富忠、伊廷华、李宏男、刘迪、周海俊、李文全

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大连理工大学土木工程学院,大连 116024

中铁第四勘察设计院集团有限公司线路站场设计研究院,武汉 430063

深中通道管理中心,中山 528411

极端环境绿色长寿道路工程全国重点实验室,深圳 518060

辽宁省交通规划设计院有限责任公司,沈阳 110111

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采样频率 频谱混叠 频响函数 阻尼比识别 傅里叶变换

国家重点研发计划资助项目国家自然科学基金资助项目国家自然科学基金资助项目辽宁省自然科学基金资助项目中央高校基本科研基金资助项目大连市科技创新基金资助项目

2022YFB260270052222807520781002023-MS-106DUT22JC192023JJ12GX018

2024

10.3969/j.issn.1001-0505.2024.01.016

东南大学学报(自然科学版)
东南大学

东南大学学报(自然科学版)

CSTPCD北大核心
影响因子：0.989
ISSN：1001-0505
年,卷(期)：2024.54(1)
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