Experimental investigation on fatigue behaviour of RTM composite cross-joints

Fatigue experiments of three kinds of composite cross-joints, processed respectively by vising resin transfer moulding(RTM), stitched RTM and co-bonding techniques, were carried out to investigate the influences of processing on fatigue behaviour, and failure mechanism was then discussed from the experimental observation. The results show that the RTM cross-joint has the highest fatigue strength in three kinds of cross-joints and the stitching and co-bonding processes have significant influences on fatigue strength of joints. Experimental observations show that the de-lamination firstly appears at upper angular point in resin-rich triangular zone of tee-joint and then propagates along the interface between resin-rich triangular zone and curved web/flange until the bottom plate, subsequently, grows along the horizontal bottom plate till failure of joint.