ABSTRACT

An embedded smart piezoelectric sensor was fabricated, and the encapsulation material was prepared with cement, epoxy resin, curing agent, and improvement additives. Structural health monitoring (SHM) methods based on dynamic stress-sensing capability of piezoelectric sensor were presented. Mechanical Testing & Simulation (MTS) amplitude-scanning and frequency-scanning dynamic loadings were designed. Mechanical performance of encapsulation material, i.e., strength, Young modulus, and stress transmitting loss; the effects of different loading frequencies on output voltages; and stress sensitivities (V/MPa), were investigated. The electromechanical impedance and mechanical responses of embedded sensors with various loadings were studied in concrete. Theoretical formula indicates that output voltage is mainly related with external stress and area of Piezoelectric Lead Zirconate Titanate (PZT) ceramic. The optimized ratio of 4:2:0.5:1.6–4:2:0.5:2 is satisfactory and it can ensure optimal mechanical performance of encapsulation material. Stress sensitivities increase with the areas of PZT ceramic, and the effects of thickness on sensitivities are not obvious. The impedance response curve has left shifting tendency with the increase of dynamic cycles and loading values. The three-point bending destruction during concrete static loading can be in real-time reflected. The embedded sensors were suitable for dynamic mechanical monitoring in concrete. The excellent mechanical sensing performance exhibits great application potentials for SHM of concrete in civil engineering.

摘要

制造了嵌入式智能压电传感器，并用水泥，环氧树脂，固化剂和改良剂制备了封装材料。提出了基于压电传感器动态应力感应能力的结构健康监测方法。设计了机械测试和仿真（MTS）振幅扫描和频率扫描动态载荷。封装材料的机械性能，即强度，杨氏模量和应力传递损耗；不同负载频率对输出电压的影响；和应力敏感性（V / MPa），进行了研究。在混凝土中研究了嵌入式传感器在不同载荷下的机电阻抗和机械响应。理论公式表明，输出电压主要与压电锆钛酸铅（PZT）陶瓷的外应力和面积有关。4：2：0.5：1.6–4：2：0.5：2的最佳比例是令人满意的，并且可以确保封装材料的最佳机械性能。应力敏感性随PZT陶瓷面积的增加而增加，厚度对敏感性的影响并不明显。随着动态周期和负载值的增加，阻抗响应曲线有向左移动的趋势。可以实时反映混凝土静载荷过程中的三点弯曲破坏。嵌入式传感器适用于混凝土的动态机械监测。优异的机械感测性能为土木工程混凝土的SHM展示了巨大的应用潜力。