Experimental modeling of fluid pressure during hydroforming of welded plates

The procedure of hydroforming belongs to one of the modern methods of sheet and tube design, usually of complex configuration. Research in the field of plastic forming using fluids usually relates to the analysis of important parameters that would enable high-quality design of elements and execution of the process in stable conditions. The hydroforming process of welded sheets found its application in manufacturing of tanks and other sheet parts in automotive industry, where, in addition to technical and technological characteristics of the obtained piece, it is necessary to achieve stability of the process and its economic feasibility. Experimental research in this paper had been aimed at the analysis of results and modeling of working fluid pressure during hydroforming of welded sheets of two kinds of material (St 37 and Al 99.5) for two sheet thicknesses (1.5 mm and 2.0 mm). Modeling was done by regression method, whose analysis is the determination of functional relationships between a dependent variable and two independent variables. Application of mathematical modeling method enabled working fluid pressure which confirmed the impact of input variables of hydroforming process (yield strength and sheets thickness) onto the values of working fluid pressure. Experimental results obtained for working fluid pressure enabled easier planning and projection of hydroforming process.