Unstable neck formation in Tensile Bars During High-Rate Tension

The time evolution of incipient necks is studied numerically for planar and axisymmetric bars subject to high-rate extension. The material is taken to be elastic-plastic and fully non-linear dynamic effects are accounted for. Two main types of growth of necks are observed; stable neck-development that results in fully developed necks and unstable neck-development that leads to weakly developed necks, since the incipient localization stops at an early state