Hans-Achim Bahr

A fracture criterion for conducting cracks in homogeneously poled piezoelectric PZT-PIC 151 ceramics

Abstract A fracture criterion for conducting cracks in piezoelectric ceramics under combined electrical and mechanical loads is proposed in connection with a measured material specific fracture curve of PZT-PIC 151. The characteristic fracture curve of the investigated material is a function of the stress intensity factor, K I , which is known from fracture mechanical concepts, and the recently defined electric field intensity factor, K E , for conducting cracks. A four-point-bending device for fracture tests under combined electrical and mechanical loads serves as the experimental set-up. The measured quantities, force, displacement, applied voltage and crack length, are used to evaluate the experiments. The finite element method (FEM) was used to determine the mechanical stress intensity factor, K I , and the electric field intensity factor, K E , taking into account linear piezoelectric coupling in the material. A qualitative process zone model is proposed for a physical interpretation of the fracture curve.

Modified four-point bending specimen for determining the interface fracture energy for thin, brittle layers

AbstractA well-known four-point bending test has been modified such that the critical energy release rate

Electrically driven cracks in piezoelectric ceramics: experiments and fracture mechanics analysis

\mathcal{G}_c

Crack deflection in piezoelectric ceramics

for delaminating cracks propagating at the interface of a thin, brittle layer bonded to a substrate can be measured. The energy release rate

3-D Modeling of Pyroelectric Sensor Arrays Part II: Modulation Transfer Function

\mathcal{G}

Threshold strength prediction for laminar ceramics from bifurcated crack path simulation

required for crack delaminating at those interfaces is obtained by attaching a stiffening layer to the layer system. Another advantage of this modification is that segmentation of the layer and plastic deformation of the substrate during bending are avoided. The interface fracture energy