Fracture analysis of strength undermatched welds of thin-walled aluminium structures using FITNET procedure

The paper presents a methodology for the residual strength prediction for the load carrying thin-walled components with highly strength under-matched welds containing cracks. The analysis is based on the strength Mismatch Option of the Fracture Module, being a part of the newly developed fitness-for service (FFS) procedure FITNET. The Mismatch Option of the FITNET Fracture Module allows for the account of weld features like the weld tensile properties and weld geometry in the fracture analysis of cracked welded components. The methodology described was verified with the generated experimental results within this investigation. The material used is an age-hardening aluminium alloy 6013 in T6 temper condition used in recent airframe components. The welds in the form of butt joints were produced using the CO2 laser beam and friction stir welding processes. The deformation and fracture behaviour as well as the special features with respect to the FITNET FFS Procedure were analyzed.The results hove shown that using the presented methodology along with newly proposed recommendations for the input data selection, conservative predictions of the maximum load carrying capacity of the large welded panels under tensile loading containing a long crack in the weld can be obtained.