Numerical simulation of the integral hydro-bulge forming of non-clearance double-layer spherical vessels: analysis of the stress state

Abstract The integral hydro-bulge forming (IHBF) of non-clearance double-layer spherical vessels is simulated numerically by the explicit finite-element code LS-DYNA3D. The stress distribution, the strain distribution and the residual stress are discussed in the present paper. The numerical results show good agreement with experimental results. Bulging deformation appears over most of the blank area; bending deformation occurs near to the blank edges and blank corners (shell vertices of the intersection area of weld seams), especially on the uncontacted areas of the outer shell; whilst high tensile stress exists at the inner surface. The residual stress may be reduced to below 20% of the yield stress of the material after bulging.