Patch Delamination Effect on Stress Intensity Factor of Cracked Steel Plates Repaired with Bonded Fiber Reinforced Polymers

摘要

Effect of bonded repair patch delamination on stress intensity factor (SIF) has been studied using finite element analysis (FEA) of cracked steel plates repaired with carbon fiber reinforced polymers (CFRP) patches. Two types of CFRP were used: sheet form, with elastic tensile modulus (E_(FRP)) of 65 GPa; plate form, with E_(FRP) of 165 GPa. Three sets of relative repair patch's axial stiffness (ETR) were analysed: 0.264; 0.53 and; 0.8. Patch delamination was modeled by progressive removal of the overstressed portions of adhesive at steel interface. Results of FEA showed that the SIF decreases with increase in the ETR using both types of the FRP but patch delamination enhances the SIF for any given ETR and crack length. Without considering patch delamination, SIF of repairs with ETR 0.264 was increased by 22 % and 30 %, respectively in lower and higher E_(FRP) repairs, for the increase in crack length from 10 to 25mm. The same comparison showed the increase as 122 % and 65 %, after introduction of the patch delamination. The delamination was found to be decreased with the increase in the ETR. The SIF of the repaired plates were also evaluated analytically using tools of linear elastic fracture mechanics (LEFM), incorporating the patch delamination and these were found to be correlating well with the finite element results.