Experimental and numerical study of the bolt reinforcement of a composite-to-steel butt-joint under three-point bending test

The behaviour of a hybrid bonded butt-joint, comprised of a double lap steel-GFRP and a GFRP sandwich composite part under three-point bending load is analysed through both numerical and experimental studies. The geometry of the joint is typical for marine applications and two possibilities of steel-to-composite connection are investigated: non-bolted and bolted. Deflection under the load point and strains at various locations of the joint were monitored and also numerically calculated. The tests revealed that the bolts used to connect the skin to steel do not have a remarkable effect on the joints capacity and stiffness in bending conditions. The numerical models can contribute to predict the structural response of the joint up to the loading at which debonding initiates and also the failure location.