Mechanics condition of thin-walled tubular component with rib hydroforming

To explore the hydroforming possibility of thin-walled tubular component with rib, mechanical analysis and finite element analysis (FEA) were conducted to investigate the rib buckling mechanics conditions. Based on lath-beam assumption, buckling Euler force was derived for rib which is restrained at one end and free at the other. The results indicate that it is possible to achieve a sound thin-walled tubular with rib component through hydroforming process and its expiation ratio can reach 20%. According to FEA, the effects of rib height and inner radius on buckling degree were studied and the threshold values of both rib height and inner radius were given. Simulation results indicate that there is a certain value for buckling and the threshold values of rib height and inner radius to thickness are 14 and 30. The formability deteriorates as rib height and rib inner radius increase. At last, the hydroforming limit diagram was drawn for hydroforming thin-walled tubular component with rib of 1Cr18Ni9. The results are useful for further study of hydroforming regularity of thin-walled tubular component with rib.