Effect of Bond Thickness on Fracture Behavior of Interfacial Crack in Adhesive Joint of Dissimilar Materials

Abstract

In this study, fracture characteristics of epoxy adhesively bondedbutt-joint of dissimilarmetals, namely SUS304 stainless steel and YH75 aluminium alloy wereexamined on variousadhesive bond thicknesses in associations with artificial interfacecrack subjected to pure mode Iloading. Finite element analysis was also executed to investigatethe stresses distribution inadhesive layer and also evaluating fracture toughness of adhesivejoints by ANSYS 11 code. Theresults show that the strength of adhesive joints without crack decreasedwith increasing bondthickness. The interface corner toughness, Hc can be applied for predictingthe strength of jointsprovided that any non-linear or fracture process zone is fully embeddedwithin the region ofsingular elastic H-field. Interfacial crack in adhesive joints propagatesin two directions, that is,along the interface (i.e. interface failure) or deviated into adhesivelayer (i.e. cohesive failure). Next,the evaluated fracture toughness, Jc of adhesive joints with interfacialcrack was independent ofbond thickness when failure was associated with crack deviated intoadhesive layer. Nevertheless,Jc for adhesive joints with interfacial crack was dependent on bondthickness when the failure wasapparently interfacial. However, if the interfacial crack is analogousto the center crack in adhesivelayer constrained between two rigid substrates, Kc parameter can beused to asses the fracturetoughness of adhesive joints with interfacial failure.