Characterization of concrete stress by measuring dissipation factors of embedded piezoelectric ceramic disc

For a novel method of characterize stress of concrete structure by measuring embedded ceramic disc, we establish a model of a piezoelectric ceramic disc under the situation mentioned above and then the relationships between the complex coefficients and the equivalent circuit parameters are obtained. Derived from the piezoelectric equations with complex coefficients, the dissipation factors are related to the equivalent circuit parameters. Experimental results show that there are linear relationships between most of the equivalent parameters and the loadings applied on the concrete structure. The mechanisms of the results are discussed by use of the theory of moving domain walls and point defects. The results also support the method of estimating the stress by measuring the value of equivalent circuit parameters of piezoelectric ceramic.