基于整体式初始位移的柔性结构低频模态试验方法

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振动与冲击 ›› 2023, Vol. 42 ›› Issue (5) : 313-322.

论文

姜东1，钱慧1，朱锐2，吴忆蒙1，胡嘉苗1

作者信息 +

Low frequency modal test method for flexible structure based on integral initial displacement

JIANG Dong1, QIAN Hui1, ZHU Rui2, WU Yimeng1, HU Jiamiao1

Author information +

文章历史 +

摘要

大型柔性结构由于刚度较低、结构庞大，采用传统测试方法难以获取结构的整体模态。提出了一种基于整体式初始位移的大型柔性结构低频模态试验方法。推导了任意初始位移条件下结构响应，以及初始位移条件下特征系统实现算法；在柔性结构上施加整体式初始位移来获取结构的整体振动响应，基于特征系统实现算法识别了大型柔性结构的低频整体模态。以长度为30米的三棱柱型桁架为研究对象，验证整体式初始位移激励下结构模态参数辨识的可行性，并讨论结构在白噪声工况下的辨识精度。采用具有理论解的集中质量柔性梁模态试验进一步验证本文所提出方法，锤击法难以激发该柔性梁的基频模态，而所提方法能够准确识别柔性梁的模态。结果表明通过在柔性结构施加整体式激励可以有效辨识出结构的低频模态参数。

Abstract

It is difficult to obtain the modes of large flexible structures by traditional testing methods due to the low stiffness and large size. A method for modal identification of large flexible structures based on initial displacement excitation is proposed. Firstly, it is theoretically proved that the structural response under monolithic displacement excitation can be approximated as an impulse response signal. Then, an integral initial displacement excitation is applied to a large flexible structure to obtain the overall vibration response of the structure. Finally, the low frequency global modes of large flexible structures are identified based on the feature system implementation algorithm. The feasibility of structural modal parameter identification under monolithic displacement excitation is verified by taking a truss with a length of 30 m as the research object, and the identification accuracy of the structure under white noise condition is discussed. The modal tests of concentrated mass flexible beams with theoretical solutions are carried out to verify the proposed method. The results show that the low frequency modal parameters of the flexible structure can be effectively identified by applying integral excitation.

导出引用

姜东1，钱慧1，朱锐2，吴忆蒙1，胡嘉苗1 . 基于整体式初始位移的柔性结构低频模态试验方法[J]. 振动与冲击, 2023, 42(5): 313-322

JIANG Dong1, QIAN Hui1, ZHU Rui2, WU Yimeng1, HU Jiamiao1. Low frequency modal test method for flexible structure based on integral initial displacement[J]. Journal of Vibration and Shock, 2023, 42(5): 313-322

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