Liguo Tang

Temperature dependence of self-consistent full matrix material constants of lead zirconate titanate ceramics

Up to date, there are no self-consistent data in the literature on the temperature dependence of full matrix material properties for piezoelectric materials because they are extremely difficult to determine. Using only one sample, we have measured the temperature dependence of full matrix constants of lead zirconate titanate (PZT-4) from room temperature to 120 °C by resonant ultrasound spectroscopy. Self-consistency is guaranteed here because all data at different temperatures come from one sample. Such temperature dependence data would make it a reality to accurately predict device performance at high temperatures using computer simulations.

Numerical analysis on laser-generated guided elastic waves in a hollow cylinder

Numerical analyses are presented for laser-generated guided elastic waves in a hollow cylinder. Time-dependent displacement at the outer surface of a hollow cylinder is expressed by summation of longitudinal and flexural type modes by employing the normal mode expansion (NME) method, then the transient waveforms excited by a single beam of laser pulse and four beams of laser pulse with an axisymmetric spatial distribution are calculated numerically. The influence of the spatial distribution of laser pulses on the waveforms are discussed in detail, and the features of major modes are explained based on dispersion curves. Finally, the total waveform of longitudinal modes obtained by the NME method is compared to that predicted by the finite element method (FEM), and a good agreement is obtained.

Temperature dependence of dielectric, elastic, and piezoelectric constants of [001]c poled Mn-doped 0.24Pb(In1/2Nb1/2)O3-0.46Pb(Mg1/3Nb2/3)O3-0.30PbTiO3 single crystal

In order to simulate the performance of electromechanical devices at elevated temperatures, full tensor properties of piezoelectric materials at high temperatures are needed. Such data are extremely difficult to get for relaxor-based single crystals because their properties are determined by domain structures, which are strongly geometry dependent. We report here the temperature dependence of full tensor material constants of [001]c poled Mn-doped 0.24Pb(In1/2Nb1/2)O3-0.46Pb(Mg1/3Nb2/3)O3-0.30PbTiO3 single crystals from 25 °C to 55 °C, which were determined by the resonant ultrasound spectroscopy. Because only one sample was used, high degree of self-consistency was achieved for the tensor constants at all measured temperatures.

Three-dimensional analytical solution for transient guided wave propagation in liquid-filled pipe systems

The objective of this study is to investigate the three-dimensional (3-D) analytical solution for transient guided wave propagation in liquid-filled pipe systems using the eigenfunction expansion method (EEM). The eigenfunctions corresponding to finite liquid-filled pipe systems with a traction-free lateral boundary and rigid smooth end boundaries are obtained. Additionally, the orthogonality of the eigenfunctions is proved in detail. Subsequently, the exact 3-D analytical transient response of finite liquid-filled pipe systems to external body forces is constructed using the EEM, based on which, the approximate 3-D analytical transient response of the systems to external surface forces is derived. Furthermore, the analytical solution for transient guided wave propagation in finite liquid-filled pipe systems is extended explicitly and concisely to infinite liquid-filled pipe systems. Several numerical examples are given to illustrate the analysis of the spatial and frequency distributions of the radial and axial displacement amplitudes of various guided wave modes; the numerical examples also simulate the transient displacement of the pipe wall and the transient pressure of the internal liquid from the present solution. The present solution can provide some theoretical guidelines for the guided wave nondestructive evaluation of liquid-filled pipes and the guided wave technique for downhole data transfer.

Determination of temperature dependence of full matrix material constants of PZT-8 piezoceramics using only one sample

Resonant ultrasound spectroscopy (RUS) was used to determine the temperature dependence of full matrix material constants of PZT-8 piezoceramics from room temperature to 100 °C. Property variations from sample to samples can be eliminated by using only one sample, so that data self-consistency can be guaranteed. The RUS measurement system error was estimated to be lower than 2.35%. The obtained full matrix material constants at different temperatures all have excellent self-consistency, which can help accurately predict device performance at high temperatures using finite element simulations.

Temperature dependence of full set tensor properties of KTiOPO4 single crystal measured from one sample

The temperature dependence of the complete set of elastic, dielectric, and piezoelectric constants of KTiOPO4 single crystal has been measured from 20 °C to 150 °C. All 17 independent constants for the mm2 symmetry piezoelectric crystal were measured from one sample using extended resonance ultrasound spectroscopy (RUS), which guaranteed the self-consistency of the matrix data. The unique characteristics of the RUS method allowed the accomplishment of such a challenging task, which could not be done by any other existing methods. It was found that the elastic constants ( c11E, c13E, c22E, and c33E) and piezoelectric constants ( d15, d24, and d32) strongly depend on temperature, while other constants are only weakly temperature dependent in this temperature range. These as-grown single domain data allowed us to calculate the orientation dependence of elastic, dielectric, and piezoelectric properties of KTiOPO4, which are useful for finding the optimum cut for particular applications.

Temperature dependence of full matrix material constants of [001]c poled 0.71Pb(Mg1/3Nb2/3)O3-0.29PbTiO3 single crystal

Up to date, there are no self-consistent full matrix data in the literature on the temperature dependence of material constants for [001]c poled (1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-xPT) single crystals because it is very challenging to measure such data for low Q-value ferroelectric materials. We report here a combined characterization method to resolve this issue using two samples. The temperature dependence of full set material constants of [001]c poled PMN-0.29PT single crystal was measured from 20 °C to 60 °C. The thickness shear mode sample was used for measuring the material constants having low sensitivity to the resonance spectroscopy method. Another thickness extensional mode sample was used for the determination of the remaining constants. Such temperature dependence of full matrix data would make accurate simulation designs and performance predictions of single crystal devices a reality, which is critically important because sample temperature will increase during the operation. This method may ...

Characterizing full matrix constants of piezoelectric single crystals with strong anisotropy using two samples

Although the self-consistency of the full matrix material constants of a piezoelectric sample obtained by the resonant ultrasonic spectroscopy technique can be guaranteed because all constants come from the same sample, it is a great challenge to determine the constants of a piezoelectric sample with strong anisotropy because it might not be possible to identify enough resonance modes from the resonance spectrum. To overcome this difficulty, we developed a strategy to use two samples of similar geometries to increase the number of easy identifiable modes. Unlike the IEEE resonance methods, sample-to-sample variation here is negligible because the two samples have almost the same dimensions, cut from the same specimen and poled under the same conditions. Using this method, we have measured the full matrix constants of a [011]c poled 0.71Pb(Mg1/3Nb2/3)O3-0.29PbTiO3 single crystal, which has 17 independent constants. The self-consistency of the obtained results is checked by comparing the calculated elastic ...

Acoustic beam control in biomimetic projector via velocity gradient

A biomimetic projector (BioP) based on computerized tomography of pygmy sperm whales biosonar system has been designed using gradient-index (GRIN) material. The directivity of this BioP device was investigated as function of frequency and the velocity gradient of the GRIN material. A strong beam control over a broad bandwidth at the subwavelength scale has been achieved. Compared with a bare subwavelength source, the main lobe pressure of the BioP is about five times as high and the angular resolution is one order of magnitude better. Our results indicate that this BioP has excellent application potential in miniaturized underwater sonars.