Threaded inserts pull-through behaviour in carbon-epoxy thick laminates

Aim of this work, is the experimental assessment of the mechanical behaviour of threaded inserts, commonly used in racing cars. Tests have been performed, both in tension and in torsion, as a function of the installation technique in composite materials. Different type of inserts have been considered to evaluate the influence of materials on the strength of the inserts. From results has been proved that the installation technique influences very little the pull through strength, whilst it mostly affects the torsion strength. In particular, the failure torque is heavily influenced whether a bonding adhesive is used or not during the insert installation. Numerical models have also been made to simulate the inserts pull-through, using the commercial code LS-Dyna®, an explicit finite element code especially used in crashworthy problems. Due to the thick composite structure, a thick shell numerical laminate has been modeled. The plies have been tied each other with a failure contact model. Numerical results show a good correlation with experimental data both in force-displacement curve and in material local damage.