Debonding development in cracked steel plates strengthened by CFRP laminates under fatigue loading: Experimental and boundary element method analysis

摘要

Carbon fiber reinforced polymer (CFRP) laminates can effectively enhance the fatigue life of steel structures. However, few studies have investigated the influence of crack-induced debonding in the CFRP-steel interface on the CFRP strengthening efficiency and the relationship of crack propagation and debonding development. This study experimentally and numerically - with the boundary element method (BEM) - investigated crack propagation and debonding development in CFRP-strengthened cracked steel (Q345, Q460, and Q690) plates. The fatigue test specimens were subjected to a maximum stress of 50% steel yield stress and a stress ratio of 0.1, during which real-time changes in CFRP strain distribution were recorded by digital image correlation (DIC). The CFRP strain gradient calculations showed that crack-induced debonding was crack length-dependent. The numerical fatigue life results were in good agreement with the experimental data when considering debonding and overestimated the experimental data without considering debonding, demonstrating the necessity of considering crack-induced debonding in calculation and design. Furthermore, a relationship was obtained between crack propagation and debonding development.