Predictive modeling of Loading paths for Hydroforming of bi-layered Y-shaped tubes

In this paper, a prediction model for the pressure-axial feed loading path in the hydroforming process of a bi-layered Y-shaped tube is developed. The plastic deformation behavior of the bi-layered Y-shaped tube in the hydroforming process is investigated by categorizing the entire process into four stages: yielding, preforming, plastic forming, and shaping. By conducting stress–strain analysis on the central unit of the bi-layered Y-shaped tube branch area and incorporating the Von-Mises yield criterion, the Levy–Mises flow rule and the principle of volume invariance, rational ranges for internal pressure and axial feed at various stages of the bi-layered Y-shaped tube hydroforming process are identified. Therefore, a predictive model for the loading path of the bi-layered Y-shaped tube hydroforming process, controlled by internal pressure and axial feed under various strain conditions, is developed. The effectiveness of the prediction model was validated through finite element simulations and experimental methods. This predictive model can be used to guide the setup of loading paths for bi-layered Y-shaped tubes and other similar inclined tee tubes.