2015 CSCE Annual Conference Regina - Building on our Growth Opportunities Conference
Dr. Jung-June Roger Cheng, University of Alberta
Fatigue behaviour of edged cracked steel plates repaired with carbon fibre reinforced polymers (CFRP) was studied experimentally under tension- tension fatigue loading, with stress range of 180 MPa and the stress ratio of 0.1. Main parameters were the CFRP modulus, adhesive thickness and adhesive shear strength. Two different moduli of CFRP were used; 165 GPa and 67 GPa. Test results showed that lesser adhesive thickness resulted in 12% reduced fatigue life for higher modulus CFRP type because of induced higher shear stresses and corresponding more adhesive failure in it, that resulted in more patch delamination and the reduced fatigue life. Lower stiffness CFRP repairs achieved higher fatigue lives because of higher adhesive shear strength although the induced shear stresses in adhesive layer was expected to be higher but on the other hand the adhesive had higher shear and bond strengths that prevented the adhesive shear failure or the patch delamination, thus resulted in higher fatigue life. Replacing lower strength adhesive with higher shear and bond strength adhesive in higher modulus CFRP repairs resulted in increased fatigue life just because of the improved adhesive bond and shear strengths. The experimental study highlighted the impact of adhesive shear and bond strengths on the fatigue life of cracked steel plates repaired with identical axial stiffness CFRP patches differed by the adhesive properties.