Assessment of the performance of structural joints using industrial adhesives

Abstract

In the adhesive bonding process, a basic understanding that both material architecture and joining process affect the strength of the structure is required. These design requirements force old techniques of joining, such as bolting and riveting to be re-evaluated. Advantages of adhesives over mechanical means of fastening include higher stiffness, more uniform load distribution, parts consolidation, no holes drilled in adherends (with resulting stress concentrations), and, generally, less labour. The following study attempts to apply testing techniques for qualification of the use of adhesives in steel structural connections using acrylic and epoxy adhesives. This study does not deal with injection of adhesive in reinforced concrete structures, for example. The dissertation deals mainly with variation of geometric properties with regards to lap joints, where other parameters like surface preparation and bondline thickness were not varied. The recommendations of the manufacturer were used in that case. A smaller length to width ratio gives higher average shear stress of the adhesive. Increasing the overlap length of the adhesive gives an increase in strength, however the increase is not proportional to the length like the width is. The toughened acrylic adhesive produced better values in most tests especially in peel tests, and where the overlap length was smaller than the epoxy adhesive.