【作者】 李旭；

【导师】 李宏男； 霍林生；

【作者基本信息】 大连理工大学 ， 防灾减灾工程及防护工程， 2015， 博士

【摘要】 压电陶瓷(如锆钛酸铅,Pb-based Lanthanumdoped Zirconate Titanates,简称PZT)材料,因其造价低廉,以及频率响应范围宽等优点,在土木工程结构健康监测领域应用前景广泛。然而,尽管压电陶瓷传感器具有很宽的频率响应范围,应用压电陶瓷传感器的结构损伤识别研究,往往只应用到某一部分频率范围的传感器信号以达到单一的监测目的。压电陶瓷传感器在宽频响应下的动态特性及多功能监测等方面的研究,有待进一步发展。本文进行了基于压电陶瓷传感器在300kHz内宽频响应的结构损伤识别技术研究,主要内容如下：(1)针对粘贴式压电陶瓷传感器与结构的耦合体系,提出了一种“压电陶瓷—粘结层—被测结构”考虑层状介质剪切应变传递的动态力学模型。分析了驱动频率对压电陶瓷传感器应变传递特性的影响。并利用该模型,分别分析了压电陶瓷片的厚度、粘结层材料、粘结层厚度对传感器动态特性的影响,所提模型的有效性用ANSYS有限元分析和试验加以验证。(2)分析了宽频激励下,嵌入式压电陶瓷传感器的动态性能,提出了一种“保护层—防水层—压电陶瓷”结构的动态力学模型。分析了驱动频率对压电陶瓷极化方向动态应力传递特性的影响,并分析了保护层、防水层的材料和厚度、压电陶瓷片的厚度对传感器动态性能的影响。利用ANSYS有限元分析和试验验证了分析的正确性。(3)分析了压电陶瓷传感器低频响应“拍”信号的形成机理,通过旋转矢量法分析了结构的阻尼效应、荷载冲击方向、传感器位置对“拍”信号的影响。根据压电陶瓷传感器“拍”信号,提出了一种荷载冲击方向的识别方法,并通过悬臂钢柱的冲击试验验证了方法的有效性。(4)提出了一种应用压电陶瓷传感器低频应力响应的结构损伤识别方法,即基于互相关函数幅值和支持向量机的损伤识别方法,该方法仅需要压电陶瓷传感器测得的结构应力响应信号,且适用于任意荷载激励。利用IASC-ASCE Benchmark模型的数值验证和桁架结构模型的损伤识别试验,验证了方法的有效性。(5)基于压电陶瓷传感器宽频响应特性,提出了一种应用压电陶瓷传感器低频的结构振动响应信号和高频声发射信号的多功能监测方法。以钢筋混凝土梁动态弯曲破坏试验为例,分析了压电陶瓷传感器在混凝土构件中的多功能监测；进行了钢筋混凝土框剪结构模型的地震破坏监测试验,利用压电陶瓷传感器的多功能性,同时分析了结构的动态特性和局部损伤情况。更多还原

【Abstract】 The piezoelectric materials (such as Pb-based Lanthanumdoped Zirconate Titanates, PZT), due to their low costs and excellent dynamic properties, have broad application prospects in structural health monitoring of civil engineering. However, even though the PZT sensors have broad frequency responses, only partial frequency range of PZT signal tends to be used. There are still further studies to be done on the dynamic properties of sensors and multi-functional applications based on the broad frequency range of piezoelectric sensors. This paper focuses on the damage identification based on the broad-frequency responses with the range from 0 to 300kHz of piezoelectric sensors. The detailed works are as followed.(1) The "PZT-bonding layer-host structures" model, which is considered as the dynamic shear strain transform model of layered medium, is proposed for the coupled system of pasted PZT sensor and host structure. The effects of dynamic strain transform properties caused by driving frequency are analyzed. In addition, the dynamic properties of sensors caused by PZT thickness, bonding layer material and thickness are also analyzed. The validity of proposed method is proved by both ANSYS and experiments.(2) The dynamic properties of embedded PZT sensor under broad frequency range excitation are analyzed. The "PZT-water proof layer-protecting layer" model, considered as the dynamic mechanical model of layered medium for embedded PZT sensor, is proposed. The effects of dynamic stress transform properties of PZT sensors caused by driving frequency are analyzed by the proposed model. In addition, the effects of sensor dynamic property, caused by manufacture craftsmanship such as materials and thickness of both protecting and water-proof layer, are then analyzed. The effectiveness of above analysis is verified by both ANSYS and experiments.(3) The formation mechanism of beat signal from low frequency response of PZT sensor in structural impact test is analyzed in the view of mathematics. The effecting factors of beat signal, such as damper effect, impact direction and position of sensor, are then analyzed by the rotate vector method. In addition, an impacting direction identification method, based on the beat signal of PZT sensor, is proposed. The correctness of proposed method is finally verified by the impacting test of steel column.(4) A damage identification method used low frequency range of PZT signal, which is based on cross-correlation function amplitude and support vector machine, is proposed. The proposed method only needs the responses of structures and is adapt for arbitrary excitations. The IASC-ASCE benchmark model is used to testify the availability of method. Moreover, the proposed method is also proved to have excellent identification effects for the damage detection of truss model.(5) Based on the broad-frequency responses of PZT sensor, a multi-functional monitoring method combining vibration test and acoustic emission monitoring is proposed. The dynamic bending test of concrete beam is taken as an example to illustrate the multi-functional monitoring on concrete members. Then the PZT sensors are applied for monitoring RC frame-shear wall structures subjected to seismic loadings. The dynamic properties of structures and local damage status are analyzed for the multi-function of PZT sensors.更多还原