Experimental investigation of the static torque transmission capabilities of the adhesively bonded single lap joints

Abstract

The carbon fiber epoxy composite materials have been widely used in the structures of aircrafts, spacecrafts, sport goods and machine elements because of their high specific moduli (E/ρ), strengths (S/ρ) and high dampings. Although the carbon fiber epoxy composite material has excellent properties for the structures, the joints for the composite materials often reduce the efficiency of the composite structures because the joints are often the weakest areas in composite structures.In this paper, the effects of the adhesive thickness on the static torque transmission capabilities of the adhesively bonded circular single lap joints have been investigated by the experimental method. Also the dependencies of the joint srengths on the stacking sequences of the composite adherends were tested. Since the circular single lap joint fails catastrophically beyond the static strength, the tubular polygonal adhesively bonded joints such as triangular, tetragonal, pentagonal and hexagonal as well as elliptical joints, which have partial mechanical joint characteristics, were manufactured and tested.From the experimental investigations, it was found that the strength of the circular adhesively bonded joints was much dependent on both the adhesive thicknesses and the stacking sequences of the composite adherends, while the polygonal adhesively bonded joints was less dependent on them.