NONLINEAR FEM SIMULATION OF THE INTEGRALLY HYDROFORMING PROCESS OF SPHERICAL TANKS WITH A SOCCER STRUCTURE

The integrally hydroforming technology of spherical tanksis a newly invented technology for manufacturing spherical tanks. And the 32-petal spherical tanks are one kind of earliest spherical tanks developed by this new technology. In the present paper the hydroforming process of this kind of spherical tanks is simulated usiug a nonlinear FEM program, the variation process .of the shell configuration and displacementsand the springback regularities are analysed, the deformation features of this kind of shells and the process measures taken are also compared with the experimental results. Three-dimensional Kirchhoff thin shell elements with 8-noded quadrilaterals are used, the displacements of the intersection points of weld seams and- the bonding effects of the shell are taken into accout. The hydrobulging process of the shell are simulated very well using FEM, and the FEM results are in good agreement with those of the experiments.