With the continuous advancement of high-end equipment in the aerospace field

titanium alloy multirib components— characterized by their lightweight design

high load-bearing capacity

and high reliability are being  increasingly used as key load-bearing structures in aircraft. However

such components often exhibit complex rib arrangements and extreme combinations of size

which can easily lead to defects during forming

such as incomplete rib filling

folding

and flow line disorder

caused by undesirable material cross-rib flow. These issues also result in concentrated die stress and excessive forming loads. In this study

finite element simulation and a self-developed visual experimental platform for rib filling were employed to systematically investigate the material flow behavior

die stress distribution

and load characteristics during isothermal forming of two-dimensional three ribs characteristic component

three-dimensional connecting ribs characteristic component and large long strip-shaped multi-rib component. The results demonstrate that the use of optimally designed unequal-thickness billets enables quasi-synchronous filling of the rib cavities

effectively suppresses cross-rib material flow

improves forming accuracy

and significantly optimizes die stress distribution. Compared with equal-thickness billets

the optimized billets reduce the maximum forming load by 17.7% for 3D components and 28.3% for large-scale components

while notably mitigating stress concentration in the die.