Obtaining Formability Characteristics Of Automotive Materials Using On‐line Strain Imaging System

The formability of automobile sheet material AA6111‐T4 was investigated in the hemispherical punch test. Specimens with various geometry and lubrication conditions were utilized to obtain a continuous strain map from a biaxial stretching. The data was processed to obtain strain path and limit strain values as measures of formability. The Strain imaging system, ARAMIS, in which a speckle pattern is utilized instead of the conventional grid system, was employed to capture the strains during the forming process. Features of the evolving dome surface, such as development of shear bands and strain localization were accurately captured and studied. Specimen profile with non‐symmetric notches for shearing test in biaxial loading was designed and investigated in both the experimental and the FE approach. The on‐line strain imaging method offers a useful approach towards developing an understanding of flow localization, formability and fracture under biaxial loading conditions.