微结构振动特性的自由衰减测试方法

Free Damping Test Method for Vibration Characteristics of Microstructures

为准确快速地对微结构的谐振频率和阻尼比进行测试和分析,组建了以激光多普勒测振仪为核心的微结构瞬态离面运动特性测试系统．附有压电驱动的微悬臂梁和微振动薄膜在斜波脉冲激励信号作用下产生自由衰减振动,通过激光多普勒测振仪将瞬态运动速度转换为模拟信号,经数据采集卡数字化后送入计算机,对其振动特性进行分析．实验测得MPA-41200-10型微悬臂梁谐振频率为48．676 kHz,阻尼比为0．002 9,微薄膜谐振频率为 25．446 kHz,阻尼比为0．042．实验结果与采用频率扫描方法测试的结果进行了对比,证实自由衰减振动法对微结构振动特性的快速测试是可行、有效的．

To test and analyze the resonance frequency and damping ratio of microstructures accurately and high-efficiently, a test system for transient out-of-plane motion of microstructurcs is built based on a laser Doppler vibrometer. A micro-cantilever and a micro-membrane, which are both attached with piezoelectric devices, are excited respectively by the ramp pulse signal and produce free damping motion Through a laser Doppler vibrometer, the transient velocity is converted to analog signals which are digitalized by a data acquisition card and then are sent into a computer to analyze the vibration characteristics. The resonance frequencies of the micro-cantilever PA-41200-10 and the micro-membrane are 48. 676 kHz and 25. 446 kHz respectively, and the damping ratios are 0.002 9 and 0.042 respectively. The results indicate that the free damping test method for vibration characteristics of microstructures is feasible and efficient compared with the sweep-frequency measurement method.