A New Approach to Identify the Ductile Damage Constants of Seamed Metallic Tube Using Hydro-Bulging Process

In present research, the numerical and experimental investigation of progressive ductile damage has been conducted in free bulging of 304 stainless steel seamed tube using oil pressure. In the numerical section, using the Lagrangian finite element method with ABAQUS/Explicit solver, the seam weld simulated as a thin strip, contains non-homogeneity factors of strength and formability. Forming Limit Diagram (FLD) criterion was used as a measure of damage initiation, as well as effective plastic displacement factor with linear approach in order to model damage evolution. In the experimental section, tensile test of tube has been conducted to attain mechanical properties and also tube free bulging has been perform. Maximum bulging diameter of tube and critical pressure were recorded at the moment of bursting. In numerical analysis, the effect of material non-homogeneity factor on critical pressure, also the outcome of effective plastic displacement on the maximum bulging diameter investigated and compared with experiments. Finally, the optimum values of non-homogeneity factor and effective plastic displacement obtained respectively equal to 0.9 and 0.05. Using these factors, the accuracy of numerical prediction for tube diameter and oil pressure at bursing moment were more than 99%.