Characterization On Concrete-PZT Ceramic Sensitive Module

Based on the proposed piezoelectric sensitive structure system for the civil engineering, a piezoelectric-embedded concrete element is designed to measure the stress and temperature of the concrete structure. Three objects are concerned in the research: the concrete, the piezoelectric ceramic, and the coupling structures of them. The theoretical analysis and experimental researches are conducted to prove the feasibility of the proposed method, and explain the technical points and the measuring principle. The contributions of this paper are listed as follows:(1) According to the basic knowledge and principle in the concrete engineering, the features and behaviors related to both the concrete material and the embedded piezoelectric ceramic are disscused. Then, a concrete smart element with an embedded piezoelectric ceramic is designed.(2) The equivalent circuit for the embedded piezoelectric ceramic is established. The complex material coefficients are introduced in the equivalent circuit to describe the energy losses occuring in the embedded piezoelectric materials. The loss mechanism is explained by the theories of the domain wall (motion) and the crystal defect. A novel method is proposed to obtain the dissipation factors of piezoelectric materials. Instead of the traditional iterative method in which measuring parameters of the different viberation modes are demanded, we suggest that the dissipation factors are evaluated by the equivalent circuit parameters of the specific viberation mode.(3) A structure is designed for the piezoelectric ceramic to be embedded in the concrete. A layer of rubber is covered on either side of the piezoelectric ceramic plate. The material and the thickness of the rubber layer are also determined. The use of the rubber layer solves the problems of the piezoelectric ceramic being embedded, including a) the electrical insulation in the concrete containing water, b) the stress accumulation on the embedded piezoelectric ceramic produced by the shrink of the concrete volume in the concretion, c) the stress concentration caused by the aggregate in the concrete materials, d) the damage on the electrodes of the piezoelectric ceramic induced by the concrete.(4) The stress responses of the embedded piezoelectric ceramic in the concretion are researched. It is found that the stress caused by the volume shrinkage will be applied on the ceramic directly, and will cause the changes of the physical characteristics of the...