Multiobjective optimization of incremental sheet hydroforming of AA3003-O: Influence of forming angle and hydraulic pressure on formability limits

This study investigates the coupled effects of hydraulic pressure and forming angle on the formability limits in incremental sheet hydroforming (ISHF) of AA3003-O aluminum alloy. A novel uniform hydraulic pressure strategy is implemented to maintain consistent load conditions during deformation and significantly enhance material deformation behavior, thereby enabling stable deformation conditions. The influence of forming angle (α), hydraulic pressure (P), step down (t z ), and forming tool diameter (D) on forming force (FF) and forming height (H) is investigated using a Taguchi L9 design and analysis of variance (ANOVA). Multiobjective optimization is performed using grey relational analysis (GRA) to minimize FF and maximize forming H simultaneously. The proposed methodology provides a robust framework for enhancing process performance and material formability. It is observed that the forming angle is identified as the most influential parameter affecting both responses. At the optimal condition (D = 5 mm, t z = 0.2 mm, α = 45°, and P = 0.01 MPa), the average FF, maximum FF, and forming height were 462.0 N, 655.4 N, and 49 mm, respectively. Experimental validation of optimized GRA results shows strong agreement with predicted values, confirming the reliability and robustness of multiobjective optimization framework. The developed method simultaneously minimizes tooling load, reduces energy consumption, and enhances formability of AA3003-O sheets, providing quantifiable benefits for efficient and sustainable manufacturing. Compared with conventional incremental sheet forming reported in literature under similar forming conditions, the proposed hydraulic-assisted strategy demonstrated approximately 8%–12% improvement in achievable forming height and delayed fracture initiation.