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

Abstract

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-toaluminum). 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.

On the prediction of bolted single-lap composite joints

“…The accuracy of failure criteria was validated through compari son with experiments in literature [13]. The experiments consisted in the analysis of bolted single lap composite joints strength where results were influenced by secondary bending and torque tighten ing.…”

“…A FE numerical model reproducing a bolted single lap joint according to [13] was developed using the ABAQUS/Standard code considering non linear stress calculation due to large displace ments and composite material behaviour. In addition, Riccio devel oped a FE model of these tests including a progressive damage model based on Hashin failure criteria [29].…”

“…The obtained numerical results were compared with the exper imental data from literature [13] to validate the proposed failure criteria. Moreover, the numerical predictions were compared with those of Riccio [29] who implemented a 3D progressive damage FE model, based on the Hashin failure criteria.…”

“…The bolting parameters that have been studied include geometric factors [10], material properties [11], coefficients of fric tion [12], bolt shape [13], clearance [9], and torque [14,15]. These studies have provided strategies to design composite bolted joints avoiding catastrophic failure.…”

“…The accuracy of failure criteria was validated through compari son with experimental data found in literature [13]. To analyse the influence of non linear shear stress strain relationship in the pre diction of bearing failure, the results were also compared with those obtained by Riccio using 3D Hashin failure criteria [29].…”