Numerical Investigation on Influence of Grooves on Tube Hydroforming Process of Aluminium Alloys

For several decades, scientists and engineers have been using the tube hydroforming (THF) process for numerous applications in the automotive and aerospace industries. The inert advantages like weight reduction without compromising on strength, improved part quality, better surface finish, and reduced tooling costs have motivated the use of THF in the fabrication industry. The presence of grooves on the pre-forms was found to immensely help in increasing the pressure-withstanding capacity of the THF tubes, in addition to reducing the stress concentration and achieving the near-net shape during the THF process. This project involves the development of a detailed Finite Element Model, for the THF process. Numerical analysis is carried out in two stages: Stage-1: Groove Formation, and Stage-2: Final THF tube formation. In Stage 1, the numerical model investigates the formation of grooves, predicting the amount of internal pressure and axial feeding that are required to accurately form them. In Stage 2, numerical simulations focus on the actual THF process. This two-stage THF process (Grooved-THF) was compared to a single-stage Generic THF process. The results indicate the Grooved-THF to be producing a relatively lower thickness reduction with a more closely formed corner radius compared to the generic case. The work also involves multi-objective optimization of the process parameters like the number of grooves, coefficient of friction, internal fluid pressure, and die corner radius using the DOE technique – RSM. The results indicate the number of grooves and the friction coefficient to be the most influencing parameters in the THF process.