Example
A thin piezoelectric plate of size 25 mm x 10 mm and thickness 1.5 mm has electroding on top and bottom as shown in Fig. 30.3 (with an exaggerated view of the thickness). Assume the piezoelectric material to have elastic modulus of 65 GPa, Poisson's ratio 0.3 and electro-mechanical coupling coefficients, d31 and d32 to be −50x10 −12 m/V and 200x10 -12 m/V, respectively. Find out the strains in the plate when it is subjected to a voltage of 300V and a an axial force of 20 N.
Figure 30.3 : A typical piezoelectric plate with axial load and elastic field
Solution
Following Fig. 30.2 and eqn. (30.6), the active strains in the plate are:
since, d31 = d32 ,  - strain . Also, since a tensile force of 20 N is acting on the plate along the x-direction, the structural strain along x-direction is  , and the structural strain along y -direction is  . Hence, the total strain along x -direction is 10.02 μ -strain and the total strain along y -direction is 9.99 μ -strain .
Congratulations! You have finished Module 5.
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