Dynamic fracture behavior analysis of functionally graded piezoelectric materials with defects

Compared with traditional piezoelectric materials, functionally graded piezoelectric material (FGPM) have characteristics of continuous change of mechanical properties (such as, piezoelectric constant, dielectric constant, elastic modulus, density, etc.) along a certain direction, they can avoid stress concentration and effectively prolong the service life of components made with them. In practical engineering, interface structure in materials often contains cracks, cavities and other forms of defects. Under external load, the area near defects is easy to have stress concentration and even fracture. At present, studying fracture problems of functionally graded piezoelectric materials is limited to a single form of defects, i.e., there are only cavities or cracks on material interfaces, and less studies are focused on composite defects. Here, a calculation method for analyzing dynamic stress concentration in crack tip field of biphasic FGPM with interface crack defects excited by cavity edge under the action of anti-plane shear wave was proposed. By using Green function method, the coordinate transform method and the crack "cutting" and "fit" technique to construct the mechanical model, the crack problem was converted into solving the 1st kind of Fredholm type integral equation to obtain the theoretical expression of dynamic stress intensity factor (DSIF). Finally, a numerical example was given to analyze effects of defect geometry, incident wave characteristics and material heterogeneity on DSIF. The correctness of the results was verified by comparing themselves with results obtained using Griffith crack model. © 2022, Editorial Office of Journal of Vibration and Shock. All right reserved.