Fundamental Differences between Fracture Behavior of Thin Sheets under Plane Strain Bending and Tension

A numerical investigation of thin sheets under plane strain tension and bending is presented. Bending simulations are based on a VDA plane-strain bending test while tensile simulations depict a notched plane-strain tensile coupon. A comparative analysis of the stress and strain distributions inside the localized zone of deformation is performed for two investigated modes of behavior. The analyses suggests significant stress state differences in bending and tension driven primarily by the through-thickness response. The results offer insight into fundamental differences in tensile and bending fracture behaviors of thin sheets, as evidenced by discrepancies in strain at fracture experimentally measured using notched tensile coupons comparing to VDA bend tests. The consequences of these differences for material characterization and model calibration for large-scale crash simulations are also briefly discussed.