Development of bulge test for aluminum sheet metal

Abstract

The bulge test is frequently used experiment to characterize the material stress-strain response at the highest possible strain levels. It consists of a metal sheet placed in a die with a circular opening. It is clamped in place and inflated with hydraulic pressure. This paper presents the development of a measuring system to be incorporated in a hydraulic bulge test machine, which allows stressstrain determination up to higher levels of plastic deformation. A continuous increasing of pressure produces a biaxial tension applied to a sheet metal specimen up to breaking point. By measuring the vertical displacement using a transducer and the strain variation with an extensometer, one can estimate the strain and stress being applied to the specimen. Preliminary results indicate the efficiency of the procedure to obtain real time data for stress-strain sheet metal characterization.