1500 KSME International Journal, Vol. 18 No. 9, pp. 1500~1511, 2004 Transient Response of a Permeable Crack Normal to a Piezoelectric-elastic Interface" Anti-plane Problem Soon Man Kwon Department of Mechanical Design & Manufacturing, Changwon National University, 9 Sarim-dong, Changwon, Kyongnam 641-773, Korea Kang Yong Lee* School of Mechanical Engineering, Yonsei University, Seoul 120- 749, Korea In this paper, the anti-plane transient response of a central crack normal to the interface between a piezoelectric ceramics and two same elastic materials is considered. The assumed crack surfaces are permeable. By virtue of integral transform methods, the electroelastic mixed boundary problems are formulated as two set of dual integral equations, which, in turn, are reduced to a Fredholm integral equation of the second kind in the Laplace transform domain. Time domain solutions are obtained by inverting Laplace domain solutions using a numerical scheme. Numerical values on the quasi-static stress intensity factor and the dynamic energy release rate are presented to show the dependences upon the geometry, material combination, electromechanical coupling coefficient and electric field. Key Words:Anti-Plane Shear Impact, Piezoelectric-Elastic Composites, Permeable Crack, Intensity Factors, Electromechanical Coupling Coefficient 1. Introduction Piezoelectric materials generate an electric field when subjected to strain fields and undergo de- formation when an electric field is applied. This inherent electromechanical coupling is widely exploited in the design of many devices like trans- ducers, sensors and actuators. In addition, piezo- electric materials are a primary concern in the field of advanced lightweight structures where the smart structure technology is now emerging (Crawley, 1994). By bonding or merging piezo- electric members within a structure it is possible to control the structure behavior through elec- trically induced strain fields and, conversely, employ the strain-induced electric field as a feed- * Corresponding Author, E-mail: KYL2813@yahoo.co.kr TEL: +82-2-2123-2813;FAX: --82-2-2123-2813 School of Mechanical Engineering, Yonsei University, Seoul 120-749, Korea. (Manuscript Received June 17, 2003; Revised June 3, 2004) back driver. The effective control of piezoelectric smart structures can be achieved by means of the optimal combination of structural and control elements, which allows using all the benefits of the electromechanical coupling. On the while, due to the brittle behavior of piezoelectric ma- terials, reliable service lifetime predictions de- mand a comprehensive understanding of the frac- ture process in the presence of electromechanical coupling. In many engineering applications, these piezoelectric structures may experience transient dynamic loads as well as steady harmonic loads. It is, therefore, of great importance to investigate the transient dynamic response of cracked piezo- electric structures. A finite crack in an infinite piezoelectric ma- terial under anti-plane electromechanical impact was investigated by Chert and coworkers (Chen and Yu, 1997 ;Chen and Karihaloo, 1999) with an impermeable crack boundary condition. The same problem of an anti-plane shear wave in an infinite piezoelectric medium were considered by Chen and Yu (1998) with the impermeable