THE EFFECT ON ADHESION STIFFNESS DUE TO BONDED SURFACE CONTAMINATION

When bonded joints fail at less than design loads, it is often due to either insufficient surface preparation or an inadequate adhesive cure process. Generally, the failure process is recognized through adheren d end peel and adhesive or cohesive failure. The typical interpretatio n of the failure mechanism suggests that weak bonds can only be recogn ized by early failure. However, recent experimental investigations hav e indicated that faulty bonding does affects the adhesion stiffness an d this can be detected by non-destructive testing without having to re sort to destructive testing. This paper discusses these findings and p ostulates a new approach to load transfer in adhesively bonded lap joi nts which possess weakened bondlines.