The tensile properties of adhesively bonded single lap joints with short kevlar fiber

In this paper, short Kevlar fiber was added to epoxy resin adhesive to form a short fiber toughened adhesive, and its effect on the static strength and elongation at break of Carbon fiber laminate adhesively bonded single lap joints was investigated. 1 wt%, 2 wt%, 3 wt% and 4 wt% short Kevlar fibers were added to make short fiber toughened adhesive joints to investigate the effects of different contents of short Kevlar fibers on the connecting properties of the test pieces of Carbon fiber laminate single lap adhesively bonded joints; In addition, microscopic toughening mechanism of short Kevlar fiber in adhesives revealed by combining DIC technique and SEM technique. The test results showed that the addition of appropriate amount of short Kevlar fiber could slow down the crack extension compared with the without toughening specimens, but the toughening effect was weakened by excessive content. 2 wt% short Kevlar fiber toughened specimens achieved the best toughening effect, with 30.52 % increase in peak load and 25.78 % increase in elongation in tensile test. The combination of DIC and SEM further showed that short Kevlar fiber toughened joints absorb crack strain energy through fiber-bridging thus increasing adhesive properties.