The fatigue life of MIG welded cruciform joint failing from root (LOP) region was successfully predicted using new fracture mechanics equations. These equations were developed by combining Paris' law and AK~-endurance equation and incorporating an integral factor (Ip), obtained by integrating Paris' equation. In the numerical formulation of the equation, the initiation life (Ni) and propagation life (Np) of the joint were accounted for to obtain the total fatigue life (Nf). The initiation life was obtained experimentally using crack "Initiation Criteria". The propagation life was evaluated using the numerically developed equations. The method outlined successfully predicted the fatigue life of the joint from its crack growth parameters. To test the accuracy of the method, the predicted data were compared with the experimental data. It was found that the predicted data compared quite well with the experimental data. This method is simple and can be applied easily for other joint geometries. a, a 0 and a i f*(a) m A~,A2 B Bt , B2 C G Ci, C2 and C 3 F(a) L AK i and AK W N N,, Np and Nr R L ? P A~r
NOMENCLATURE
crack length, lack of penetration and initial crack, mm normalised stress intensity factor (SIF) crack growth exponent compliance factors in Frank's eq. ( 4) fillet's width, mm constants in eqs (l") and (3") Paris' constant, Nmm unit Paris' constant (initiation) constants in eqs (3'), ( 25) and ( 13) factor in eq. ( 20) weld leg length, mm initial and steady state SIF range, MPav/m specimen's width, mm value of integral no. of cycles initiation, propagation and failure cycles stress ratio, O'min/O'ma x plate thickness, mm constant in eq. ( 19) constant in eq. ( 10) constant in eq. ( 10) constant in eq. ( 20) stress range, MPa slope in eq. ( 20) superscript for normalisation.