Study On Longitudinal Strain Constant Measurement Of Piezoelectric Ceramics

Piezoelectric ceramics are functional materials that have a wide range of application within industry, as well as in high-tech fields such as laser, military, medical science, etc. And measuring the characteristic parameters of piezoelectric materials is very important, particularly the piezoelectric constant d33which describes the coupling relationship between elastic properties and dielectric properties of piezoelectric material.With the use of static method, quasi-static method, and dynamic resonance method, the parameters of piezoelectric ceramic materials can be quantified. The above measurement methods apply different principles, and their relative measuring results differ. Moreover, deviations also exist in the situation of using different measurement devices under the same principle. So far, no reports on uncertainty evaluation and consistency of different measurement methods seen. Basing on this point, the paper analyzes different measurement principles, and establishes measurement systems of dynamic resonance method and quasi-static method respectively, and then researches on the influential factors during the measurement process and the consistency of different measuring methods. The main work includes:1. The paper sets up the measurement systems of quasi-static method of piezoelectric ceramic parameters, and analyzes the factors such as dynamic stress value needed, measurement frequency range and loading mode. It calculates the uncertainty of quasi-static method by analyzing influential factors. The results showed that the frequency and magnitude of dynamic forces have a large impact on the measurement results, while the time decay of d33can be acceptable.2. The paper sets up the measurement systems of dynamic method. Through dynamic resonance method, and a series of piezoelectric parametric tests on electromechanical coupling coefficient, dielectric constant, the resonant frequency, the piezoelectric constant, analysis of piezoelectric ceramics parameter measurement methods and influencing factors. Experimental results show that the samples need to select different step frequency corresponding to the sizes, inappropriate gripping manner will result in admittance circle drawn defects.3. From the definition of the piezoelectric constants, the consistency of results given by different methods was discussed. Comparing the measurement results of quasi-static method with dynamic resonance method, the results showed the similar trend. Due to differences in the measurement frequency range, the measured values of piezoelectric constant slight deviation.