Plasticity and Formability of Annealed, Commercially-Pure Aluminum: Experiments and Modeling

Abstract

The plasticity and formability of a commercially-pure aluminum sheet (AA1100-O) is assessed by experiments and analyses. Plastic anisotropy of this material is characterized by uniaxial and plane-strain tension along with disk compression experiments, and is found to be non-negligible (e.g., the r-values vary between 0.445 and 1.18). On the other hand, the strain-rate sensitivity of the material is negligible at quasistatic rates. These results are used to calibrate constitutive models, i.e., the Yld2000-2d anisotropic yield criterion as the plastic potential and the Voce isotropic hardening law. Marciniak-type experiments on a fully-instrumented hydraulic press are performed to determine the Forming Limit Curve of this material. Stereo-type Digital Image Correlation is used, which confirms the proportional strain paths induced during stretching. From these experiments, limit strains, i.e., the onset of necking, are determined by the method proposed by ISO, as well as two methods based on the second derivative. To identify the exact instant of necking, a criterion based on a statistical analysis of the noise that the strain signals have during uniform deformation versus the systematic deviations that necking induces is proposed. Finite element simulation for the Marciniak-type experiment is conducted and the results show good agreement with the experiment.

Flange Wrinkling in Deep-Drawing: Experiments, Simulations and a Reduced-Order Model

“…They are then heattreated at 343 • C for 5400 s (1.5 h), followed by air-cooling. The mechanical and forming properties of this material have been extensively characterized in earlier works [17,18]. Here, circular AA1100-O blanks of 35 diameter and 0.51 mm thick are produced via waterjetting.…”

“…where the fitting parameters are shown in Table 2 [17]. Since it is difficult to obtain an explicit expression from Equation ( 12) with the Voce model, numerical integration method is adopted to obtain the stress distributions in the flange.…”

Transient Hardening and R-value Behavior in Two-step Tension and Loading Reversal for DP980 Sheet

“…The R-value in figure 1(b) was determined by the plastic strain ratio of strain in width and thickness directions as described in Equation (2). To characterize the anisotropic yielding of the DP980 sheet, plane-strain tension (PST) and disk compression tests [9][10][11][12][13] were additionally conducted to calibrate the anisotropic yield function Yld2000-2D [14] as shown in figure 2. These experiments were post-processed as in our earlier work, e.g., [9,11].…”

Deep-Drawing of Commercially-Pure Niobium Sheet

“…The "plane-strain" tension tests also showed some deviation from the ideal zero-transverse strain case, with an trasverse/axial strain ratio of about -1/3, hence in this work they are considered biaxial tension tests, instead (details can be found in [13]). This is also partially because of the high R-value in RD and TD, and the unsuitable geometry used for this material (although the same geometry was highlily statisfactory for other materials [3,4,6,[17][18][19]). Despite that, the biaxial tension tests provide useful biaxial loading information for the anisotropy calibration.…”

“…A thorough evaluation of these properties requires welldeveloped experimental setup and careful analysis. Typical sheet metal characterization experiments involve uniaxial tension tests, cruciform tests, bulge tests, plane-strain tension tests or disc compression tests, and have been often used to establish the hardening and plastic anisotropy of sheet metal [1][2][3][4][5][6][7]. For Nb in particular, Zamiri and Pourboghrat [8] conducted a set of uniaxial tension tests and proposed an evolving yield function to capture its anisotropy.…”