Piezoelectric Ceramics Functional Characterization Under Uniaxial Compressive Stress

The aim of this work is to determine the nonlinear electro-mechanical behavior of piezoceramics subjected to an external uniaxial compressive stress. An experimental setup using a compression machine has been developed. A stress is applied along the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$z$</tex>-axis (poling direction) on a bar-shape sample. The use of a video-extensometer allows us to measure the elastic compliance from the local axial strain. Piezoelectric charges are indirectly measured with an electrometer to determine the piezoelectric coefficient. Hysteretic stress - strain and stress - electric displacement behaviors were found under cyclic compressive stress for soft and hard PZT materials. The non-linearity of the elastic and direct piezoelectric responses for high uniaxial stress as well as the sample memory effect are observed. A finite element model is built to assess the mechanical evolution with respect to the applied stress. This can be essential to predict the ferroelastic response of a given piezoelectric ceramic subjected to a certain stress.