Evaluation of Impact Shear Strength of Adhesive Joints with the Split Hopkinson Bar

Abstract

The shear strength of adhesive joints at high loading rates is evaluated with the split Hopkinson bar technique using a pin-and-collar specimen. A commercially available cyanoacrylate adhesive (commonly termed an instantaneous adhesive) and two different adherend materials are used in the tests. The impact shear strength of the cyanoacrylate adhesive joints is determined from the applied shear stress history at failure initiation. Comparative shear tests at low loading rates are carried out on an Instron testing machine. The influences of loading rate, thickness of adhesive layer, and adherend materials on the shear strength of the cyanoacrylate adhesive joints are examined. The test results indicate that the shear strength increases significantly with increasing loading rate, and is greatly affected by both the adhesive layer thickness and adherend materials. It is shown that the shear strength increases to a maximum at an adhesive layer thickness of about 25 μm and subsequently decreases. The advantages and limitations of the technique are also discussed.