Automated apparatus for dynamic mechanical analysis using the piezoelectric ultrasonic composite oscillator technique

Abstract

Computer-controlled apparatus for the measurements of dynamic Young's modulus and internal friction as functions of temperature, using the piezoelectric ultrasonic composite oscillator technique (PUCOT), has been designed and demonstrated. The versatility of the apparatus and its resonance tracking techniques have been proven by detecting subtle structural phase transformations within the Ca1−xSrxTiO3 perovskite system as well as dramatic changes accompanying the martensitic transformation in a Au–Cd shape-memory alloy. The simplicity of the PUCOT technique allows a system such as this to be constructed easily and with low cost.

Ferroelastic crystals and their nonlinear elastic properties observed in frequency range from gigahertz to milihertz

“…To investigate sound velocity in ferroelastic crystals which do not exhibit piezoelectric properties, the composite oscillator bar (COB) method can be applied [29][30][31][32][33][34][35]. The COB method makes use of the piezoelectric properties of a quartz rod that transmits vibrations to the sample glued to the end of the rod ( Figure 5).…”

“…The other parameters B 20 and E 20 are independent of temperature. Through the gradient operator introduced in the functional (29) both, the interaction of fluctuations of n and m parameters and the presence of the spatial (uniaxial) modulation of the OPs n and r have been taken into regard. In order to determine the temperatures at which the functional G can have anomalies, the first derivatives of energy G with respect to n 0 and r 0 have been calculated, and retaining the terms linear in n 0 and r 0 , the following equations have been obtained:…”

“…It is known that the transitions of this type are of first order and they cannot be described by Equation (29). However, as shown in [77,78] the coupling of the stress with solitons can induce the second-order character of the PT from the incommensurate to the commensurate phase.…”