Effects of Geometrical and Material Features on Damage Onset and Propagation in Single-lap Bolted Composite Joints under Tensile Load: Part I – Experimental Studies

An experimental investigation has been carried out in single-lap bolted composite joints in order to point out the influence of geometrical and material characteristics on the damage onset and propagation under tensile loading conditions. Protruding and countersunk joints have been considered, with different bolt diameters and different interfaces (composite-to-composite and composite-to-aluminum). First, static tensile tests have been performed on single-lap joints. Then, non-destructive ultrasonic evaluations have been conducted at intermediate load levels and at final failure in order to show the real onset and evolution of damage inside the joints in terms of fibers and matrix breakage