A NEW FRACTURE-MECHANICS METHOD TO PREDICT THE FATIGUE LIFE OF WELDEDCRUCIFORM JOINTS

The fatigue life of MIG welded cruciform joint failing from root (LOP) region was successfully predicted using new fracture mechanics equati ons. These equations were developed by combining Paris' law and Delta K-i-endurance equation and incorporating an integral factor (I-p), obt ained by integrating Paris' equation. In the numerical formulation of the equation, the initiation life (N-i) and propagation life (N-p) of the joint were accounted for to obtain the total fatigue life (N-f). T he initiation life was obtained experimentally using crack ''Initiatio n Criteria''. The propagation life was evaluated using the numerically developed equations. The method outlined successfully predicted the f atigue life of the joint from its crack growth parameters. To test the accuracy of the method, the predicted data were compared with the exp erimental data. It was found that the predicted data compared quite we ll with the experimental data. This method is simple and can be applie d easily for other joint geometries.