A new experimental approach for obtaining diffuse-strain flow stress curves

Edge Fracture Prediction of Traditional and Advanced Trimming Processes for AA6111-T4 Sheets

“…Efforts have been proposed for determining the material stress-strain relationships at large strains using the hydraulic bulge test [17][18][19] and shear test [20]. Attempts also have been made to estimate the local stress and strains within diffused necks [21][22][23] with the use of Bridgman corrections [24].…”

Formability Characterization of Titanium Alloy Sheets

“…The most commonly used method to investigate the flow stress curve is uniaxial tensile test in which true stress-true strain curve is expressed in uniaxial stress state. However, maximum plastic strains obtained in uniaxial loading condition is not sufficient for most sheet metal forming simulation processes which involve biaxial state of stress [1][2][3][4][5]. Hydraulic bulge test is a comparative test method in which biaxial stress-strain curve could be attained.…”

“…In 1950, a key theoretical pillar for the hydraulic bulge test was established by Hill [6]. In his study, Hill assumed a circular profile for the deforming work piece which allowed for the introduction of a closed form expression for the thickness at the pole region [5].…”

Overview on constitutive modeling for hydroforming with the existence of through-thickness normal stress

“…So the effective stress-effective strain curve obtained above cannot properly express the mechanical properties of the anisotropic material unless the effect of R-value is considered. Smith et al (2009) proposed a new bulge formulation based on 2D Hill48 anisotropic yield criterion with a plane stress assumption. Compared with other methods in determining the flow stress curve, such as cruciform-biaxial, torsion, shear and moment-curvature, the bulge test is more reliable for diffuse necking regions.…”