Experimental investigation of double-lap bolted composite joints with different outer plates subjected to bending loads

A double-lap bolted composite joint was designed. In the joint, the base material was woven glass fibre–reinforced epoxy (WGF/Epoxy) composite, and the outer plates were WGF/Epoxy, woven carbon fibre–reinforced epoxy (WCF/Epoxy) and WGF/WCF/Epoxy hybrid composite laminates, respectively. Fundamental mechanical properties of the composite panels were determined. Flexural testing of the designed bolted joints was performed. Scanning electron microscopy was used to compare the damage modes. The interlaminar curves could be divided into different stages. The flexural load–displacement curves had progressive damage characteristics. The strengths of joints with hybrid composite panel as outer plates were between those of pure specimens, and hybrid composites with WGF as contact surface had a positive hybrid effect.