# Springback Behavior of AA 7075-T6 Alloy in V-Shaped Bending
## 2 Simulation Study
### Validation of Finite Element Model  
This section presents a validation study to compare the springback behavior of an AA 7075-T6 aluminum alloy at room temperature, using experimental testing and finite element simulations. The validation was performed through V-shaped bending tests utilizing 120\({}^{\circ}\) dies. The aluminum specimens used in the experiments had dimensions of 6 mm in thickness, 25 mm in width, and 200 mm in length. Testing was carried out on a DENER press machine with a capacity of 135 tons. All bending tests were conducted by the ASTM E290 standard, with a constant test speed of 1 mm/s. Each test was repeated three times to ensure repeatability. Following the bending process, the springback angles of the specimens were measured using a digital protractor. The experimental setup and sample geometry are illustrated in Figure 3. Finite element validation model of V-shaped bending is given Figure 4.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Temperature** & **Young’s Module** & **Yield Strength** & **Tensile Strength** & **Elongation at** \\ (\({}^{\circ}\)C) & **(GPa)** & **(MPa)** & **(MPa)** & **Break (\%)** \\ \hline RT & 70 & 540 & 582 & 20 \\ \hline
100 & 68 & 520 & 545 & 23 \\ \hline
200 & 65 & 400 & 385 & 24 \\ \hline
300 & 59 & 123 & 130 & 26 \\ \hline
400 & 52 & 35 & 40 & 50 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Temperature-dependent material properties.  
Figure 2: True stress–true strain curves of AA 7075-T6 at RT, 100 \({}^{\circ}\)C, 200 \({}^{\circ}\)C, 300 \({}^{\circ}\)C, 400 \({}^{\circ}\)C.  
A finite element model was developed to replicate the experimental setup and validate the simulation methodology. The simulations were carried out using the ANSYS(tm) 2024 R1 software. A semi-symmetric model was constructed to enhance computational efficiency. The aluminum specimen and the die and punch components were modeled using 3062 PLANE183 elements and a total of 9619 nodes. Frictionless contact conditions were defined at the interfaces between the punch and sheet and between the sheet and die. Geometric nonlinearity was enabled in the analysis to accurately capture the large deformations occurring during the V-shaped bending process. The finite element validation model is shown in Figure 5. Additionally, Figure 5 includes the post-bending view of the aluminum specimen and the von Mises stress distribution in the model, both before and after the springback phase.  
Figure 4: Finite element validation model of V-shaped bending. (**a**) Meshed model. (**b**) Boundary conditions of the model.  
Figure 3: The experimental setup and test specimen; (**a**) Test machine; (**b**) Test specimen.  
After the test, the springback value of the 6 mm thick sample was measured as 8.5\({}^{\circ}\). From the finite element analysis, the springback value was obtained as 8\({}^{\circ}\). The difference between the test and simulation is at an acceptable level. It was observed that the experimental and simulation images in Figure 5a,b are compatible. The comparison of springback values indicates a strong agreement between the experimental results and the finite element simulations, confirming the validity of the developed model and the simulation approach. Consequently, this modeling methodology can be confidently employed to investigate the V-shaped bending behavior of aluminum alloys under elevated temperature conditions.  
A schematic view of the springback angle calculation is given in Figure 6.  
Figure 5: Test and simulation results. (**a**) Specimen view of the aluminum plate after the V-shaped bending test, (**b**) von Mises stress distribution of the FE model after the springback, (**c**) von Mises stress distribution of the FE model before the springback.  
Figure 6: Schematic view of springback angle calculation.