Necking of a Metallic Thin Sheet Followed by Speckle Pattern Interferometry
Résumé
In this paper, we analyze plastic strain localization in a sheet specimen by electronic speckle pattern interferometry during uniaxial tensile tests. A model, which is independent of material characteristics, was used to describe the whole strain rate field with two crossing localization bands inclined with respect to the tensile direction. Thus, the physical features of localization, such as the width of the two bands, their inclination angles and their maximum strain rates are identified by least-square from the displacements fields and their evolutions are followed from the onset of diffuse necking up to the failure. In particular, the effect of the average strain rate is considered. It was found that: • The band width decreases exponentially vs. the maximum local strain; • The inclination of the band leading to fracture is quite stable, while the other rotates toward a situation perpendicular to the tensile direction; • No significant effect of the average strain rate is observed. It was, however, only varied by a factor 2.