Stress intensity factors (KI) of cracked non-load-carrying cruciform welded joints repaired with CFRP materials

The adhesively bonded fiber reinforced polymer (FRP) material repair technique has been employed to repair welded joints with defects and extend the fatigue life of welded structures. In this paper, non-load-carrying cruciform welded joints patched with carbon fiber reinforced polymer (CFRP) sheets were studied with the finite element method. A total of 230 cases, where cruciform welded joints were patched with CFRP sheets, were analyzed. Stress intensity factors (SIFs) of mode I (K-I) at the crack tip were investigated to evaluate repair performance. It was found that K-I can be significantly reduced by CFRP repairing. The effects of the amount of the repair materials, crack depth and patching sides were also evaluated. The results show that the increase of the elastic modulus of the CFRP and adhesive could significantly decrease the SIF at the crack tip and that the reduction of K-I became more evident with crack depth. Single-sided repairs at the cracked surface were better than double-sided repairs with regard to the surface crack at the weld toe. However, differences between the two repair methods became negligible with increased crack depth. (c) 2012 Elsevier Ltd. All rights reserved.