Effect of tapering on interfacial stresses in adhesive joints without adhesive fillet

Paper in proceeding, 2008

Using bonded Fiber Reinforced Polymer (FRP) laminates is an effective, durable and economical method for strengthening and upgrading of existing structures. A major prob-lem using this method is the high interfacial stresses in the adhesive joint near the ends of the laminate which governs the failure of the system in most cases. A method to reduce the interfacial stresses at these locations is tapering the laminate end with or without adhesive fillets at the end of the joint. The effect of tapering on the state of interfacial stresses in adhesive joints without fillet is investigated using FE-analysis. Both normal and reverse tapering is considered with tapering lengths vary between 1 and 20 times the thickness of the bonded laminate. The results indicate that using laminate tapering technique without adhesive fillet may lead to increase in peeling stress component in the joint. The effect of tapering on interfacial stress components was found to be dependent on the stiffness of the bonded laminate and adhesive used. It can be concluded that decision on using taper in adhesive joints should be made considering the material properties such as stiffness of the strengthening elements and through-thickness strength of the composite laminate.