Prediction of Forming of AA 5052-H32 Sheets under Impact Loading and Experimental Validation

The present study aims to elaborate the influence of bending prestrain, pressure, and sheet thickness on the forming behavior of AA 5052-H32 sheets deformed at a high velocity using a shock tube. The forming parameters, including the dome height, strain evolution, effective strain, and stress distribution, are evaluated through shock tube experiments and finite element simulations in DEFORM-3D; the numerical and experimental results are compared for validation. The rate-dependent material properties from both the prestrained sheets and the shock-deformed sheets are incorporated into the simulations. The forming process is modeled in a single step without considering prestrain application. Instead, the mechanical properties obtained from the actual prestrained sheets are provided as input to the numerical models before forming. The sharp increase in strain evolution matches quite well with the experimental results obtained by the strain rosette. This agreement confirms the strain rate of the sheet during the forming process. Circular grids are printed on the sheets, and Hill’s yield criterion is used to calculate the effective strain. Moreover, Hollomon’s power law is used to calculate the effective stress in the same location. The simulated effective stress and strain distribution matches quite well with the experimental results with a slight overprediction. The distribution of the stress and strain confirms the uniform stretching of the material without strain localization. The variation in the forming parameters indicates that the forming behavior is dependent on the degree of prestrain, and the forming parameters increase monotonically with the increase in pressure.