Multiple collinear cracks in a piezoelectric material

In this paper, an exact solution of multiple collinear cracks in piezoelectric material is obtained. The permittivity of air (environment) is considered. Two cases have been studied. In the first case, the permittivity of air is far less than that of piezoelectric material. Therefore, the electric induction in the air is negligible. In the second case, the permittivity of air is comparable with that of piezoelectric material. The problem is deduced into Riemann-Hilbert problem and solved. By the way, the electric boundary conditions are discussed. This result demonstrates that the consideration of air in crack gap reduces the stress intensity factor. (C) 2001 Elsevier Science Ltd. All rights reserved.