In this paper, some novel micro/nano- moire grating fabricating techniques are introduced. The gratings are produced by the SPM lithography, FIB lithography, and molecular beam epitaxy (MBE) method. The moire patterns formed with these gratings are also introduced. The gratings are successfully to be used to measure the residual deformation in the surface around a step edge of the Al/Si artificial nanocluster with the moire methods. The successful experimental results verify the feasibility of these methods.
This paper introduces how to in situ observe fracture behavior aroung a crack tip in ferroelectric ceramics under combined electromechancial loading by use of a moire interferometry technique. The deformation field induced by electric field and stress concentration near the crack tip in three-points bending experiments was measured. By analyzing the moire interferometry images it is found that under a constant mechanical load, an electical field has no effect on crack extension in the case that the directions of the poling, electric field and crack extension are perpendicular to each other. When the poling direction is parallel to the crack extension direction and perpendicular to the electric field, strain decreases faster than values predicted by the theoretical analysis as the distance away from the crack tip increases. In addition, as the electric field raises the strain near the crack tip increase, and the strain concentration phenomena becomes more significant.
Domain switching near the crack or notch tip is important in the study of fracture in piezoelectric materials. The ABAQUS finite element piezoelectric element was used in conjunction with the domain switching code developed for prediction of domain switch zone by performing a nonlinear analysis. Domain switching zones in the vicinity of the crack tip were obtained using the work and energy density criteria corresponding to combined electrical and mechanical loads. Comparison is made to indicate the differences in the prediction by the two domain switching criteria. Experiments are conducted with uniform single crystal BaTiO<SUB>3</SUB> and notched single crystal BaTiO<SUB>3</SUB>. The difference in the intensity of the polarized light is used to identify the out-of-plane domains and the in-plane domains.
This paper introduces how to in situ observe fracture behavior around crack tip in ferroelectric ceramics under combined electromechanical loading by use of a moire interferometry technique. The deformation field induced by electric field concentration near crack tip in three-points bending experiments was measured. By analyzing the moire interferometry images it is found that strain decreases faster than values predicted by the theoretical analysis as the distance away from the crack tip increases.
Conference Committee Involvement (1)
Behavior and Mechanics of Multifunctional Materials and Composites III
9 March 2009 | San Diego, California, United States