Four Possibilities of Piezoelectric Effect

Every piezoelectric coefBdeiit di in Eq. (5.9) corresponds to the certain relationship between specific mechanical stress componerrt T/ and to the specific component of electric displacement D,. Four different cases of piezoelectric effect could be distinguished according to the direction of electric displacement and component of mechanical stress. Situation is schematically displayed in Fig. 5.2 

Coefficients d, d2i and d-ij, describe the longitudinal piezoelectric effect (see symbol L in Table 5.1). The normal mechanical stress component causes piezoelectric polarization parallel to it in such case. Second possibihty is the piezoelectric polarization perpendicular to the applied normal mechanical stress. Such piezoelectric effect is so called transversal effect (see symbol T in Table 5.1) and it is characterized by one of the coefficients di2, d -i, J21, dj2, dn or J32. Application of shear mechanical stress might result in the piezoelectric polarization perpendicular to the plane of applied shear. Such shear piezoelectric effect is called longitudinal shear (see symbol 5l in Table 5.1) and it is characterized by one of the piezoelectric coefficients du, d25 or d e- Second possibility of shear piezoelectric effect is the piezoelectric polarization parallel to the plane of the applied shear stress. Such effect is called transversal shear (see symbol in Table 5.1 and in Fig. 5.2). This effect is related to one of the piezoelectric coefficients J15, di, d24, d26, d- orc 35. 

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Table 5.1 Four possibilities of piezoelectric effect - longitudinal, transversal, longitudinal shear and transversal shear...

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