Reference-Free Crack Diagnosis Based on Polarization Characteristics of Smart Materials

基于智能材料偏振特性的无参考裂纹诊断

• 批准号: 0700411
• 负责人: Hoon Sohn
• 金额: $ 14万
• 依托单位: Carnegie-Mellon University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-09-01 至 2010-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0700411&HistoricalAwards=false
• 关键词: Reference; Free; Crack; Diagnosis; Based

This project will develop a new concept and theoretical framework of nondestructive testing (NDT), in which damage can be detected without using past baseline data. In particular, a NDT methodology will be formulated for detecting cracks in metallic structures commonly used in civil applications. A new NDT methodology will be developed based on the premise that certain types of damage can be instantaneously detected without direct comparison with previously obtained baseline data. First, the theoretical framework for the reference-free diagnosis will be developed based on the polarization characteristics of lead zirconate titanate (PZT) wafer transducers. Then, features that are sensitive to damage but insensitive to ambient variations of the bridge structures in the field will be extracted by comparing two instantaneous collected signals without referencing to past baseline data. Here, active sensing devices such as lead zirconate titanate will be used to generate and measure guided waves in metallic structures. Once damage-sensitive features are identified, statistical classifiers will be developed to establish decision boundaries without using prior reference data and to minimize false indications of damage. Finally, realistic environmental and operational conditions that in-service bridges are subject to will be explicitly considered through a field test of the Buffalo Creek Bridge in Pennsylvania. This strategy offers a potential for a significant breakthrough in SHM/NDT practice via the integration of active sensing, smart materials, statistical pattern recognition techniques and new theoretical development for damage diagnosis that has not been attempted to date. This field deployable NDT technique will be unique because (1) damage diagnosis can be accomplished without relying on prior reference data, (3) the monitoring system will have its own intelligence that autonomously converts real-time sensor data to damage diagnosis information without requiring data interpretation by the end users, (4) the NDT paradigm can be applied to complex geometries such as welded/bolted connections where cracks often occur, and (5) environmental and operational variations that in-service structures experience will not affect damage diagnosis, minimizing false indications of damage. This will be a significant advancement to non-destructive testing of RC structures.The degree of technical advancement and attendant quality improvement for both civilian and defense infrastructure provided by the NDT methodology, combined with a broad range of potential applications, render this research of significant value. The NDT methodology will reduce complexity and costs related to visual inspection, data collection, data interpretation and expensive false alarms of damage. The autonomous decision making procedure render this NDT methodology attractive for continuous long-term monitoring of bridge structures. Successful development of the instantaneous reference-free NDT methodology has the potential for an enormous positive impact in condition assessment and monitoring for civil infrastructure, mechanical systems, aircraft, and many others. Furthermore, the body of knowledge obtained in this research will pave the way for commercial entities to adapt this technology to their own market places. Finally, owners of safety critical systems in all fields will be the biggest beneficiaries as the NDT translates into fewer inspections, better performance and a decrease in the total cost of ownership.

该项目将开发一个新的概念和理论框架的无损检测（NDT），其中可以检测到损坏，而不使用过去的基线数据。特别是，NDT的方法将制定用于检测在民用应用中常用的金属结构的裂纹。 一种新的无损检测方法将被开发的前提下，某些类型的损坏可以立即检测到没有直接比较与先前获得的基线数据。首先，无参考诊断的理论框架将开发基于锆钛酸铅（PZT）晶片换能器的偏振特性。然后，特征是敏感的损坏，但不敏感的环境变化的桥梁结构在现场将被提取通过比较两个瞬时收集的信号，而不参考过去的基线数据。 在这里，诸如锆钛酸铅的主动感测装置将用于在金属结构中产生和测量导波。一旦确定了对损伤敏感的特征，将开发统计分类器，以在不使用先前参考数据的情况下建立决策边界，并尽量减少对损伤的错误指示。最后，将通过宾夕法尼亚州布法罗河大桥的现场测试，明确考虑在役桥梁所处的实际环境和运行条件。 这种策略提供了一个潜在的一个重大突破，在SHM/NDT实践中通过集成主动传感，智能材料，统计模式识别技术和新的理论发展的损伤诊断尚未尝试的日期。 这种可现场部署的NDT技术将是独特的，因为（1）可以在不依赖于先前参考数据的情况下完成损伤诊断，（3）监测系统将具有其自身的智能，该智能自主地将实时传感器数据转换为损伤诊断信息，而不需要最终用户的数据解释，（4）NDT范例可以应用于复杂的几何形状，例如经常发生裂纹的焊接/螺栓连接，以及（5）在役结构所经历的环境和操作变化不会影响损伤诊断，从而使损伤的错误指示最小化。 这将是一个显着的进步，以无损检测的RC structues.The程度的技术进步和随之而来的质量改进为民用和国防基础设施所提供的无损检测方法，结合广泛的潜在应用，使这项研究的重要价值。无损检测方法将减少与目视检查、数据收集、数据解释和昂贵的损坏假警报有关的复杂性和成本。自主决策程序，使这种无损检测方法有吸引力的连续长期监测的桥梁结构。瞬时无参考无损检测方法的成功开发对民用基础设施、机械系统、飞机等的状态评估和监测具有巨大的积极影响。此外，在这项研究中获得的知识将为商业实体将这项技术应用于自己的市场铺平道路。最后，所有领域的安全关键系统的所有者将成为最大的受益者，因为NDT可以减少检查，提高性能并降低总拥有成本。