PurposeThe process of hydroforming is defined as the formation of parts into the internal mold design using internal pressure. This process can extensively reduce parts and secondary operations, and adoption to the loading path is one of its most essential points. The purpose of this paper is to address these issues.Design/methodology/approachA dynamic loading path was taken into account in the current study, and a drop hammer was employed for this purpose, decreasing the time and requiring less number of systems.FindingsOne of the main observations of this research is that selecting side punches with a smaller central hole radius is proportional to the kinetic energy and the amount of fluid. Moreover, it can be effective in achieving the optimal loading path.Originality/valueIn addition to experiments for numerical analyses, the finite element simulation model was provided via Abaqus software in which the Eulerian–Lagrangian coupling method was utilized for evaluating the tube forming process through repeating the fluid flow formation because of the effect. Moreover, the genetic programming model was efficient for determining the most suitable input parameters regarding prediction for the minimum thickness which examined the efficiency of the process and presented a mathematical relationship.

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In this paper, the evolution of a ductile damage in the 7075-T6 aluminum alloy is considered based on stress state parameters with a special focus on pre-mechanical working dependency. Uniaxial stress–strain curves are investigated experimentally for two conditions; specimens with shock loaded pre-mechanical working and without it. This kind of loading is applied in order to find out impulsive pressure effects of damage variation procedure. Some experiments are done to take different stress states. Applying two fracture initiations criteria, i.e., Hosford–Coulomb and Xue models, two types of fracture locus of Al-7075-T6 are predicted in terms of plastic strains and stress state parameters under above conditions. By considering experimental data, a new ductile damage evolution model is proposed among plastic behavior. It is introduced by explicating an uncoupled plasticity and related to initial rate dependent stress state. By using both fracture models, our damage evolution model is implemented, phenomenologically as well as the Xue damage model, to compare results.

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