J ournal of Solid Mechanics and Materials Engineering Vol. 4, No. 7, 2010 974 974 1, I F = Stress Intensity Factor of an Interface Crack in a Bonded Plate under Uni-Axial Tension* Nao-Aki NODA**, Yu ZHANG**, Xin LAN**, Yasushi TAKASE** and Kazuhiro ODA*** ** Department of Mechanical and Control Engineering, Kyushu Institute of Technology, 1-1 Sensui- cho, Tobata-ku, Kitakyushu-shi, Fukuoka, Japan E-mail: noda@mech.kyutech.ac.jp *** Tokuyama College of Technology, Gakuendai, Shunan-shi, Yamaguchi,Japan Abstract Although a lot of interface crack problems were previously treated, few solutions are available under arbitrary material combination. This paper deals with a central interface crack in a bonded infinite plate and finite plate. Then, the effects of material combination on the stress intensity factors are discussed. A useful method to calculate the stress intensity factor of interface crack is presented with focusing on the stress at the crack tip calculated by the finite element method. For the central interface crack, it is found that the results of bonded infinite plate under remote uni-axial tension are always depending on the Dunders’ parameters α , β and different from the well-known solution of the central interface crack under internal pressure that is only depending on β . Besides, it is shown that the stress intensity factor of bonded infinite plate can be estimated from the stress of crack tip in the bonded plate when there is no crack. It is also found that dimensionless stress intensity factor 1 I F < when ( 2 )( 2 ) 0 α β α β + − > , 1 I F > when ( 2 )( 2 ) 0 α β α β + − < , and 1 I F = when ( 2 )( 2 ) 0 α β α β + − = . Key words: Elasticity, Stress Intensity Factor, Fracture Mechanics, Finite Element Method, Interface Crack, Bonded Plate 1. Introduction An interface crack in an infinite bonded plate under internal pressure in Fig.1 (a) is known as the most fundamental and well known solution for interface cracks. The stress intensity factor is given in Eq.1. (1) It is also known that the interface crack under remote biaxial tension as shown in Fig.1 (b) is equivalent to the one in Fig.1 (a). In Fig.1 (b), y σ σ ∞ = is the remote tensile stress in the y direction, and 1 2 , x x σ σ ∞ ∞ are the ones in the x direction so as to produce the same strain in the x direction 1 2 x x ε ε = along the bi-material interface (1) . As shown in Fig.2 (a), a central interface crack in a bonded plate has been treated in the previous studies (2)-(4) , and some noticeable results are provided in Table 1. As can been seen from this table, those results almost coincide with each other. However, the limiting solution as 0 aW → in Table 1 has not been discussed yet in the previous studies. In Table 1 it is seen that dimensionless stress intensity factor I F does not approach unity although 0 II F → as 0 aW → . In other words, it is confirmed that the solution under uni-axial tension in Fig.3 (b) is not equivalent to Eq. (1). *Received 16 Nov., 2009 (No. e84-1) [DOI: 10.1299/jmmp.4.974] ( )(1 2 ) , I II I II K iK F iF i a ε σ π + = + + 0 II F = Copyright © 2010 by JSME