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提出一种对薄膜的振动模式进行定性分析和识别的方法—结构光条纹时间平均法。该方法采用结构光三维传感技术,用低帧频商用CCD相机记录由光栅投影到振动薄膜面上、因薄膜振动导致条纹局部模糊的一系列变形正弦条纹,经过傅里叶变换、频谱滤波、逆傅里叶变换、取模等处理得到被测薄膜的振动模式分布。本文给出了该方法的理论分析,推导了相应的计算公式。计算机模拟和实验验证了该方法的可行性:能够对在不同激励频率下薄膜的振动模式进行定性分析和识别。在实验中,如果连续改变振动物体的振动激励频率,可以清楚地观察到物体振动模式的变换过程。实验证明,本文方法具有数据获取速度快,全场测量,实验装置简单等优点。
A method of qualitative analysis and identification of the vibration mode of film is proposed. The method uses structured light three-dimensional sensing technology to record a series of deformed sine fringes which are projected onto the vibrating membrane surface by a grating with a low frame rate commercial CCD camera and partially streaked due to the vibration of the membrane. Through Fourier transform, spectral filtering, Inverse Fourier transform, modulo and other processing to get the vibration mode distribution of the film under test. This paper gives the theoretical analysis of the method, derived the corresponding formula. Computer simulation and experiment verify the feasibility of this method: the vibration modes of films can be qualitatively analyzed and identified under different excitation frequencies. In the experiment, if we continuously change the vibration excitation frequency of the vibrating object, we can clearly observe the transformation process of the object vibration mode. Experiments show that this method has the advantages of fast data acquisition, full field measurement and simple experimental setup.