Experimental validation of optimisation strategies in hydroforming of T-shaped tubes

For three dimensional tube hydroforming operations (i.e. T or Y shaped tubes) the calibration of both material feeding history and internal pressure path during the process is crucial and many approaches to such optimization were presented; the authors developed some procedures to optimize pressure paths and punch velocity histories with the application of an integrated method FEM - Gradient based optimization tools. In this paper, an experimental validation campaign of the utilized optimization strategies is presented with the aim to assess the effectiveness of the developed procedures. An optimization procedure (gradient based techniques) was applied on the process parameters leading to the determination of an optimal pressure path. Finally, a testing machine was set up to carry out hydroforming operations on T-shaped tubes. The developed equipment allows a computer assisted control of both the internal fluid pressure paths and the punches actions (material feeding paths). The experimental evidences validated the results obtained by the optimization strategies utilized to design the process parameters.