Cryogenic Fracture of Cracked Piezoelectric Ceramics in Three-Point Bending under Electric Fields
Yasuhide Shindo (Tohoku University), Fumio Narita (Tohoku University)
Prager Medal Symposium in honor of George Weng: Micromechanics, Composites and Multifunctional Materials
Tue 10:45 - 12:15
MacMillan 117
Lead zirconate titanate (PZT) ceramics in special electronic devices for hydrogen applications (e.g., space, automobile) are subjected to cryogenic temperatures. In the application of the multilayer PZT actuators to active hydrogen fuel injectors, the actuators are also operated under electric fields at cryogenic temperatures. On the other hand, high mechanical stresses and intense electric fields in the PZT ceramics during service may cause microcracks to develop which eventually lead to failure of the devices. Hence, it is important for reliability and durability to investigate the fracture behavior of piezoelectric ceramics at cryogenic temperatures. In this study, we present theoretical and experimental results on the cryogenic fracture behavior of single-edge precracked piezoelectric ceramics under electric fields, using three-point bending methods. The crack was created normal to the poling direction. Fracture tests were carried out at room temperature and 77 K, and the fracture loads were measured. Plane strain finite element analysis was also performed considering temperature-dependent material properties of the piezoelectric ceramics, and the energy release rate was calculated. The effects of electric field and temperature on the energy release rate were then discussed. Furthermore, the fracture surfaces were examined using SEM to correlate with fracture behavior.