Interfacial fracture of piezoelectric multilayer actuators under mechanical and electrical loading

Abstract

The fracture behaviour of metal-piezoceramic interfaces under mechanical and electrical loading is examined by four point bending using commercial multilayer actuators. The experiments are performed under stable crack growth in a custom made very stiff testing machine. Besides mechanical loading, a constant electric field was methodically switched on in longitudinal specimen direction. Both poled and unpoled actuators were tested. The crack morphology and the fracture toughness depend on the type of the metal-ceramic interfaces. Assuming different electrical crack boundary conditions of a permeable and an impermeable crack, the field intensity factors K ic , with i = 1, 2, 3, and energy release rates G c (K ic ) at the measured critical loads are evaluated with linear-piezoelectric finite element calculations. Inside the bounds of the electrically induced mixed-mode angles, the permeable crack boundary condition yields a constant interface toughness .

Influence of small cyclic and DC electrical loads on the fracture toughness of ferroelectric ceramics

“…E.g. R-curves under electromechanical loading were measured for SENB-PZTspecimens by Jelitto et al [18,19] and for SENB-PZTactuators by Häusler et al [20]. Both did not observe a decisive change of the critical mechanical loads as a consequence of a DC electric field of one third of the coercive field E c .…”

Analysis of a Griffith crack at the interface of two piezoelectric materials under anti-plane loading

“…The weak-discontinuous interface fracture in a non-homogeneous piezoelectric bi-material structure is considered in [20]. Häusler et al [13] studied the fracture behavior of metal-piezoceramic interfaces under mechanical and electro-mechanical loading using commercial multilayer actuators. The dynamic behavior of a Griffith crack situated at the interface of two bonded dissimilar FGPM is displayed in [34].…”

Crack initiation patterns at electrode edges in multilayer ferroelectric actuators

“…The permeable conditions assume that crack faces are closed and the electrical fields are not perturbed by the presence of the crack. These conditions have been checked to be realistic based on the fracture behavior of metal-piezoceramic interfaces in commercial multilayer actuators (Haeusler et al 2009). Theoretical studies also show that the permeable conditions are a reasonable approximation when the electrical discharge strength of the medium within the crack is small, in the order of that of air (Landis 2004a, Li et al 2008).…”