FINITE-ELEMENT ANALYSIS OF BULGE FORMING APPLYING PRESSURE AND INPLANE COMPRESSIVE LOAD

Bulge tests for the determination of material characteristics are very common in engineering analysis. Apart from test purposes, the bulging technique is utilized for the forming of metal sheet-plate or tubes t o various useful shapes. Both theoretical and experimental analysis of this forming technique have been done by several authors for differen t initial blank forms. Finite-element analysis of bulge forming has be en carried out by a few authors. In these analyses, the bulging of dia phragms were simulated with edges clamped and hydraulic pressure appli ed as forming load. Finite-element analysis of the process incorporati ng the contact phenomenon between the die and sheet-plate has not been reported in the literature. The application of in-plane compressive l oad on the sheet-plate has also not been reported in any analysis. Thi s paper attempts to study the effect of combined pressure and in-plane compressive load on the sheet-plate by the finite-element method. The contact condition between the die and the sheet-plate is also taken i nto consideration in the analysis. Further, the analysis is undertaken also for the pressure-only loading case and the results are compared. It is seen from the analyses that the bulge height obtained in the co mbined loading situation is much higher than that in the pressure-only loading situation. The bulge from the former has a more straight part and thinned less throughout. It also developed less stress and strain compared to the bulge formed in the pressure-only loading situation. (C) 1998 Elsevier Science S.A. All rights reserved.