Influence of mechanical stresses on partial discharge in a piezoelectric solid containing cavities

For a piezoelectric solid with an air-filled elliptic cavity, the two-dimensional problems of partial discharge inside the cavity are studied when the solid is subjected to combined mechanical stress and electric field. Based on the law of Paschen, the influence of mechanical stress on partial discharge is discussed. It is shown from the obtained results that the applied mechanical stress can retard or enhance the occurrence of partial discharge, which is dependent on the signs of applied electric fields. It is also found that for a mathematical crack (with zero initial width), partial discharge may not happen even when the significantly high mechanical and electric loadings are applied within the range of practical interest.