Research on Influence of Loading Speed of Structural Two-component Epoxy Adhesives on Adhesive Bond Strength

Adhesive bonds belong among a prospective technology of materials connecting, they are applied in many industrial branches when single applications use many advantages of these constructional bonds among which also good shear strength can be ranked. Just the shear strength of the adhesive bond belongs among factors determining an applicability of single adhesives. Standards describing the experimental determination of the adhesive bond shear strength specify the time which is needed for reaching the bond failure. For an extension of adhesives specification for given application the definition of the shear strength can be spread also of other speeds. The paper deals just with the determination of the time influence which is necessary for breaking a steel test adherent on the resultant shear strength of structural adhesives. An electron microscopy was used for an evaluation of fracture surfaces. The aim of the performed experiment is to describe the influence of changeable rate of deformation of the adhesive bond on the shear strength. From the result of the constructional carbon steel S235J0 testing the increase of the breaking strength and yield strength at increasing loading speed is obvious. At increasing loading speed the fall of the elongation of the adhesive bonded material occurred. From the results it is obvious that the loading speed of the adhesive bonds has a positive influence on the strength results of tested adhesive bonds. It came to the increase of the adhesive bond strength up of 21-57% at the speed 500 mm·min-1.