Fatigue strength of CFRP strengthened welded joints with corrugated steel plates

This paper presents an experimental and numerical research on the carbon fibre reinforced polymer (CFRP) strengthened welded joints with corrugated plates. The effectiveness of the strengthening in the improvement of fatigue strength has been examined experimentally on the test joints through varying the number and the layout of the CFRP laminates. The test results show that the joints with transition curvature region reinforcement and single side reinforcement produce slightly lower rigidity but longer fatigue life in contrast to those with full width reinforcement on the double side of the main plate. Furthermore, a simplified two dimensional analytical model which allows for the geometric characteristics of the joint has been proposed to investigate the stress intensity factor of mode I. The proposed analytical model has been simulated by finite element technique and its solution result is compared with previously reported theoretical calculation. Parametric studies have been performed to investigate the effects of the number of CFRP layers and the moduli of carbon fibre & adhesive on the stress intensity factor. The combined influence of the corrugation angle and crack depth has also been considered. It has been found that these effects on the stress intensity factor are more significant for the joints with smaller corrugation angle.