基于主动声激励和面振动探测的原位结构缺陷检测技术

From the view of practical requirements of defect detection for precision instruments, we propose an inspection method based on active acoustic excitation and surface vibration detection to achieve non-contact and non-destructive testing for the internal defects of precision instruments without disassembly. The method aims at the structural defects including debond, fissures and looseness. In our research, we use the acoustic wave produced by the Parametric Acoustic Array to excite the precision instrument with frequency-scanning and impulse signals. Then, the vibration response signals are measured by the combination of heterodyne interferometry and a CMOS-DVR system. Eventually, a multi-parameter fusion method is used for recognition and location of the defects. The acoustic excitation method is capable for non-contact, in situ excitation of precision instruments without disassembly, as well as targeted excitation of local regions. The heterodyne interferometry technique not only rapidly detects vibration information of high-density points, but captures real-time images of objects, providing abundant information for defect inspection. The multi-parameter fusion method enhances the sensibility and accuracy for structural defect detection effectively. The research is of significant importance for life assessment and troubleshooting of precision instruments.

本项目从实际精密仪表缺陷检测需求出发，针对精密仪表长期贮存和使用中产生的脱胶、裂缝、松动等结构缺陷，给出一种基于主动声激励和面振动探测的原位结构缺陷检测方法，实现在无需拆装分解下对精密仪表内部缺陷进行非接触无损检测。采用声学参量阵激发的声波对精密仪表施加扫频及冲击振动激励，运用基于CMOS-DVR快速图像采集系统的外差干涉面振动检测技术测量振动响应，然后通过多参数融合的振动信号分析方法实现结构缺陷的识别及定位。该方法的特色在于，研究的声波激励方式可以实现装配状态下精密仪表的无损、原位振动激励，能够对局部区域进行针对性的振动激励；研究的外差干涉面振动检测技术不仅能够快速探测高密度采样点的振动规律，而且实时获取被测物体像，为结构缺陷检测提供更丰富的信息。研究的基于面振动信号的多参数融合结构缺陷识别方法，能够有效提高缺陷检测的敏感性和准确性。本项目研究对精密仪表寿命评估、故障排除等具有重要意义。

在精密仪表生产、加工和使用过程中会产生多种结构缺陷，这些缺陷会反映为结构振动特性参数的改变，因此振动特性参数的识别和分析已经成为精密仪表性能评估和健康监测的重要手段。为此，本课题研究了一种基于主动声激励和面振动检测的无损检测方法，可以用于精密仪表缺陷的无损检测。首先，针对外差干涉振动检测方法的理论和解调方法进行分析和仿真，给出了一种基于CMOS-DVR快速采样的外差干涉面振动检测方法。其次，针对振动特性参数检测的需求，将主动声激励方法与面振动检测方法结合给出一种无损的实验模态分析方法，可用于模态频率、模态振型等参数的提取。最后，将该技术成功应用于石英振梁加速度计摆片检测，为石英振梁加速度计摆片的性能评估和加工工艺改进提供有效的数据支撑；应用于电路元器件的检测，通过局部振动特性的变化实现了损伤和缺陷检测。本课题的研究成果发表于《Mechanical Systems and Signal Processing》（《机械系统与信号处理》）、《Applied Optics》（《应用光学》）等高水平期刊上，为精密仪表的健康监测提供一种无损、非接触式、全视场成像的检测手段。