Piezoelectric Transducer With Displacement Amplification

In piezoelectric transducers with displacement amplification the achieved deflection is increased by constructive means. The stiffness of such a design decreases with the square of the displacement amplification ratio and is therefore much smaller than in the stack design. 

The highly elastic material region of the displacement amplifier in Fig. 6.19a is locally concentrated, while the designs in Fig. 6.19b and c make use of the global elastic behaviour of metallic materials. The so-called moonie transducer in Fig. 6.19b consists of a piezoelectric disk sandwiched between two metal end caps. The ceramic is poled in the thickness direction and uses the dai mode. In this way the small radial displacement of the disk is transformed into a much longer axial displacement normal to the surface of the 

With the above introduced principle, it is usually possible to implement an amplification factor of up to 10. Greater values are constructively possible but quickly lead to a worsening of the djmamic behavioiu of the entire system. 

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