Structural Damage Detection and Evaluation Using a Scanning Laser Vibrometer

使用扫描激光测振仪进行结构损伤检测和评估

• 批准号: 0120798
• 负责人: P. Frank Pai
• 金额: $ 16.84万
• 依托单位: University of Missouri-Columbia
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-10-01 至 2005-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0120798&HistoricalAwards=false
• 关键词: Structural; Damage; Detection; Evaluation; Using

Inspection of aging civil structures, after-earthquake buildings and bridges, aging aircraft, and mechanical systems under fatigue loading requires a method that can perform on-site quick and accurate damage detection of large structures. Unfortunately most of conventional non-destructive inspection methods are local methods; it is slow and expensive to use them for on-site inspection of large structures. Because damage signals are always contained in dynamic responses of structures, this research project is to develop a dynamics-based global inspection method for the detection and estimation of defects in large composite and built-up structures. Toward a global inspection method a scanning laser vibrometer will be used to provide accurate and dense measurement of Operational Deflection Shapes (ODSs) of structures, and a newly developed Boundary Effect Evaluation (BEE) method will be used to extract damage-induced boundary effects from the ODSs to reveal damage locations. The BEE method is a model-independent method; it uses a sliding-window least-squares curve-fitting method to decompose an ODS into central solutions and boundary solutions. Because damage introduces new boundaries to a structure, boundary solutions exist around damage and structural boundaries and hence can reveal damage locations. Moreover, crack sizes can be estimated by using stress intensity factors from fracture mechanics. Experiments have been performed to verify the capability of this BEE method in locating surface slots, edge slots, surface holes, internal holes, fatigue cracks, and stiffened sections. Numerical and experimental results indicate that the BEE method is more sensitive and reliable than other dynamics- or deformation-based methods. The accuracy and capability of this BEE method will be improved by investigating the noise patterns of ODSs, the use of low-order transverse ODSs, a new data acquisition method using a lock-in amplifier, and a systematic method of selecting ODSs for examination. This project will result in an efficient and reliable damage detection and estimation method for performing condition-based structural safety inspection of large civil, mechanical, and aerospace structures.

对老化的民用结构、震后建筑物和桥梁、老化的飞机和疲劳载荷下的机械系统的检测需要一种能够现场快速准确地对大型结构进行损伤检测的方法。遗憾的是，传统的无损检测方法大多是局部检测方法，用于大型结构物的现场检测速度慢、成本高。由于损伤信号总是包含在结构的动力响应中，因此本研究项目旨在开发一种基于动力学的大型复合材料和组合结构缺陷检测与评估的全局检测方法。对于一种全局检测方法，将使用扫描激光测振仪对结构的工作挠度形状进行精确而密集的测量，并将使用新开发的边界效应评估(BEE)方法从结构工作挠度形状中提取损伤引起的边界效应以揭示损伤位置。BEE方法是一种与模型无关的方法，它使用滑动窗口最小二乘曲线拟合法将微分方程组分解为中心解和边界解。由于损伤给结构引入了新的边界，因此边界解存在于损伤和结构边界周围，因此可以揭示损伤位置。此外，可以利用断裂力学中的应力强度因子来估计裂纹的大小。实验验证了该方法对表面凹槽、边缘凹槽、表面孔洞、内部孔洞、疲劳裂纹和加筋截面的定位能力。数值计算和实验结果表明，BEE方法比其他基于动力学或变形的方法更敏感、更可靠。通过研究ODS的噪声模式、使用低阶横向ODS、使用锁定放大器的新的数据采集方法以及系统地选择用于检测的ODS，将提高该BEE方法的精度和性能。该项目将为大型民用、机械和航空航天结构的基于状态的结构安全检测提供一种高效可靠的损伤检测和估计方法。