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本文介绍应用时域模态振动试验技术的理论依据和实验验证。时域模态振动试验技术的理论,是基于对具有粘性阻尼的多自由度系统的运动常微分方程进行改写,使成为以状态变量为形式的方程。这些方程构成了识别系统振动参数所用的数学模型。此理论既适用于集总参数系统,也适用于分布参数系统。文章特别注意了时域模态振动试验技术的实际应用。对诸如结构的激励、测量数据的极少化、数学模型阶数的确定,所需仪器数量的极少化以及结果的平均这样一些应用问題,本文都进行了审查,并提出了解决的办法。利用悬臂梁和矩形板所做的两个实验验证了时域模态振动试验技术的可用性。其中矩形板的两个固有频率十分接近,用频率扫描试验(峰值振幅)是不可能识别出来的,因为振型之间有干扰。
This article introduces the theoretical basis and experimental verification of the application of time-domain modal vibration testing technology. The theory of time-domain modal vibration testing is based on the rewriting of the ordinary differential equations of motion for viscous damping multi-degree-of-freedom systems, making them equations that take the form of state variables. These equations form the mathematical model used to identify the vibration parameters of the system. This theory applies to both lumped parameter system and distributed parameter system. The article pays special attention to the practical application of the time-domain modal vibration test technology. In this paper we review and propose solutions to such problems as structural excitation, minimization of measurement data, determination of the order of mathematical models, minimization of the number of instruments required, and averaging of results. Two experiments using cantilever and rectangular plate verify the usability of the time-domain modal vibration test technique. Where the two natural frequencies of the rectangular plate are very close, frequency sweep tests (peak amplitudes) are impossible to identify because of the interference between the modes.