PIEZO ELECTRIC MATERIAL CRACK

When the crack moving velocity increases, both the stress and the electric displacement intensity factors decrease but the electric field intensity factor increases. It is also observed that increasing the gradient of the material properties can reduce the magnitudes of the stress and electric displacement intensity factors but it has little effect on the electric field intensity factor. Different from the case of a stationary crack in an FGPM, it is found that at the tip of the crack the electric field also exhibits the singularity of the inverse square root, along with the stress and electric displacement singularities. The closed forms of the singular stress, electric field and electric displacement are obtained from the asymptotic expansion of the stresses and electric fields around the crack tip. By using the Fourier transform, the problem is first reduced to two pairs of dual integral equations and then into Fredholm integral equations of the second kind. In comparison to the previously discovered metallic oxide based piezoelectric material Barium Titanate (BaTiO3), PZT materials exhibit greater sensitivity and have a higher operating temperature.

Since the piezoelectric material is anisotropic, the corresponding. PZT is a metallic oxide based piezoelectric material developed by scientists at the Tokyo Institute of Technology around 1952. A more recent development is the coupling of piezoelectricity and electro-chemistry, termed piezo-electro-chemistry, whereby the piezoelectrically induced. Later they noticed that electrical fields can deform piezoelectric materials. The strip is assumed to be under an anti–plane mechanical loading and an in–plane electric loading and its material properties, such as the elastic stiffness, piezoelectric constant, dielectric permittivity and mass density, are assumed to vary continuously along the thickness of the strip. Piezoelectric materials have been analyzed for over 100 years, due to their ability to convert mechanical vibrations into electric charge or electric fields into a mechanical strain for sensor, energy harvesting, and actuator applications. Lead zirconate titanate (PZT) is most probably the best known material. In this paper, the problem of a functionally graded piezoelectric material (FGPM) with a constant–velocity Yoffe–type moving crack is considered. Table 1 shows the important physical characteristics of piezoelectric materials used today to generate ultrasound.

Piezo electric material