BUP sheet metal testing machines
The bulge test is a test method used for the determination of sheet metal forming properties.
In a bulge test biaxial stress-strain curves are determined using a hydraulic cupping test. The test is similar to the FLC test with Nakajima die. The cupping procedure however, takes place without friction.
The metal blank is fully clamped between the matrix and the blank holder. Under the specimen there is a chamber with oil. The drawing die pushes the oil up and forms a curvature in the specimen until a crack occurs.