Evaluation of tube formability and material characteristics: hydraulic bulge testing of tubes

Tube material properties are required for accurate design of the parts and tooling for the hydroforming process. Tensile test properties which are obtained using specimens taken from flat sheet prior to roll forming and welding change during the tube manufacturing process. This paper describes a practical test method for determining the flow stress of tube materials. This tool set, a simple stand alone hydraulic bulging fixture, was developed to expand the tubes under bi-axial loading conditions. With the use of this tool, along with analytical methods and finite element simulation, material properties can be determined for tubular workpieces. These material properties are used for subsequent finite element computer simulation of complex components manufactured from the same material. The tooling, designed for this test, may also be used to evaluate the formability and quality of the tubes.