Abstract: Based on digital video technology, video image vibration measuring system is designed with the general USB digital camera and PC as its hardware. Meanwhile, the first-order modal parameters of a simply supported beam with concentrated masses applied are identified. Vibration video acquisition and image edge detection procedures are programmed in the MATLAB environment. The displacement-time curve of the beam vibration is obtained. Modal analysis is applied to determine the natural frequencies, the damping ratio and the vibration modes of the simply supported beam. The testing results show that this testing system is feasible for realization of the vibration test for low-frequency structures.

Key words: vibration and wave, digital video, edge detection, simply supported beam model, modal parameter, vibration testing

摘要： 基于数字视频技术，以普通 USB 数码摄像头与 PC 机作为硬件设备设计视频图像测振系统，采用该测试系统识别悬挂集中质量的简支梁模型的一阶模态参数。基于 Matlab 软件编制振动视频采集与图像边缘检测程序，获取梁振动的位移时程曲线，采用模态分析确定简支梁模型的固有频率、阻尼比与振型，试验结果表明采用该测振系统实现低频结构的振动测试是可行的。

关键词: 振动与波, 数字视频, 边缘检测, 简支梁模型, 模态参数, 振动测试