Anisotropic and cyclic mechanical properties of piezoelectrics-compressiontesting

The mechanical stressing of PZT produces irreversible deformation by, the i rreversible switching of 90 degrees domains. This leads to highly anisotrop ic deformation behaviour for poled materials. The threshold stresses requir ed to produce this switching are relatively small, < 10 MPa. The strains th at can be achieved, similar to 1% are relatively large for ceramic material s. The domain switching is a thermally activated process, so that the defor mation behaviour is strain rate dependent. The cyclic stressing of PZT prod uces significant incremental increases in the irreversible strain. This beh aviour is the basis of electromechanical fatigue effects that cause the deg radation of piezoelectric materials. (C) 1999 Published by Elsevier Science Limited. All rights reserved.