Compression Test for Metal Characterization using Digital Image Correlation and Inverse Modeling

In the case of sheet metal characterization, compression tests at normal direction of the sheet can be done by means of the layer compression test. Circular cylinder specimens are commonly used for compression test but the complicated layer alignment is time consuming and may induce a wrong anisotropy characterization. This final goal explains the interest of working on elliptic shape. In this article, an elliptical cylinder specimen is proposed and tested for bulk Titanium alloy. Full-field optical technique (3D Digital Image Correlation) is used for displacement measurements by means of three camera systems (Limess), which allows out-of-plane displacement/strain fields on around 300° of the specimen. The use of this technique easily provides accurate barreling profile used to compute Coulomb friction coefficient by using inverse method. In addition, stress-strain curves computations are more accurate than conventional method, and plastic anisotropy characterization can be obtained by using the measured shape evolution of the specimen and local strain distribution.