Mechanical Strength and Failure Mode of Flow Drill Screw Joints in Coach-Peel Specimens of Aluminum 6082-T6 Sheets of Different Thicknesses and Processing Conditions

The mechanical strength and failure mode of flow drill screw (FDS) joints in coach-peel specimens of aluminum 6082-T6 sheets of three different thicknesses of 2.5, 2.8 and 3.0 mm and three different processing conditions under quasi-static loading conditions are investigated by experiments. The experimental results indicate that the mechanical strength and failure mode of FDS joints in coach-peel specimens are affected by the specimen thickness, clearance hole and stripping. The maximum load of a coach-peel specimen with an FDS joint with clearance hole increases as the thickness increases. For each of the thickness groups of 2.5, 2.8 and 3.0 mm, the maximum load of a coach-peel specimen with an FDS joint without clearance hole is lower than that with clearance hole. For the thickness group of 2.8 mm, the maximum load of a coach-peel specimen with a stripped FDS joint with clearance hole is lower than those of non-stripped ones with and without clearance hole. The FDS joints in coach-peel specimens of different thicknesses with and without clearance hole and stripping can have the screw head penetration, the lower sheet pull out and the screw pop out failure modes, depending on the specimen thickness, clearance hole and stripping.