Pre-form design for hydro-forming process of combined ellipsoidal shells by response surface methodology

In order to obtain a reasonable pre-form shell design for the needed sound ellipsoidal shell, a research has been conducted on variation of axis lengths during hydro-forming process of the combined ellipsoidal shell with double generating lines. Numerical simulation was carried out for parametric study of the pre-form shells with different structural parameters according to the Box-Behnken design method, and a mathematical response model between axis lengths and structural parameters was developed by multivariate quadratic regression analysis. Experiments were then carried out for hydro-forming process of the combined ellipsoidal shells with double generating lines. The deformation of the shell shape was separately reported, and the variation of axis lengths was recorded. Subsequently, comparative analysis of axis lengths between experimental data and predicted data coming from mathematical response model was deeply discussed. The comparison results show that the variation of axis lengths can be well predicted by the mathematical response model, which indicates that the needed ellipsoidal shell can be easily obtained by the optimization design of pre-form shell.