基于应力波的智能骨料相控阵列与混凝土结构健康监测方法研究

Major infrastructures protect the safety of people’s life and property, and support the social stability and economic prosperity. To prevent catastrophic failure, this project aims to develop an in-situ SHM system for concrete structures. By analyzing the damage-related signal features, the SHM system is able to identify various types of damage. The smart aggregate (SA), which is manufactured as a piezoelectric ceramic patch encapsulated by a water-proofed concrete block, can correctly excite and capture elastic waves without compromising the original performance of concrete. To improve the immunity to electromagnetic interference, a new encapsulation process is proposed. The damage-related wave features are extracted from the measured signals through signal processing technique, to form damage indices which are further utilized to identify damages through an intelligent algorithm. Since the damage-related waves are vulnerable to other boundary reflections, the smart aggregate phased array is developed to amplify the damage reflection, enhance the identification accuracy, achieve the beamforming at an arbitrary point, and extend the applicability to complex structures. The elastic wave theory, smart material, signal processing technique and intelligent algorithm involved in this project, can highly promote the interdisciplinary development, and serve as the foundation for smart structures with the capabilities of self-sensing, self-adapting, self-diagnosing and self-healing.

重大基础设施保障着人民生命财产安全，维系着社会稳定和经济繁荣。为了预防结构突然失效所导致的灾难性后果，本项目拟研发混凝土结构的健康监测系统，基于应力波信号变化识别早期损伤。通过封装压电陶瓷，制备既能收发监测信号，又不影响混凝土原有工作性能的智能骨料。针对高频应力波信号易受电磁波干扰的问题，改进了智能骨料封装工艺，提高其抗干扰能力。通过实验动态监测结构状态，利用信号处理技术分析监测信号，获取对损伤敏感的信号特征，在此基础上，提出损伤指标，发展损伤识别智能算法。针对损伤回波弱，易受其他边界回波淹没的问题，研发智能骨料相控阵列，对结构内任意点处实现波束成形，加强损伤回波能量，提升识别精度，满足复杂混凝土结构的健康监测要求。本项目涉及的波动理论、智能材料、信号处理和智能算法，促进学科交叉，为实现具有自感知、自适应、自诊断和自修复能力的智能结构奠定基础。

本项目提出了一种智能骨料的改进制备工艺，提升了智能骨料对测试电路电磁串扰的屏蔽性能，构建了智能骨料健康监测系统；提出了一种吸波有限元边界，对利用应力波进行损伤识别的物理过程进行了动态模拟；提出了基于传感器阵列的信号相位延迟叠加控制算法，实现了传感器阵列的协同接收和相位控制；提出了基于应力波信号特征参数的损伤指标，实现了二维结构中损伤位置的确定；建立了混凝土构件中裂纹深度的量化监测；定量阐明了混凝土抗压强度随发育龄期的变化规律。