OICC Press Journal of Solid Mechanics 2008-7683 12 4 2020 09 30 A New Approach for Stress State - Dependent Flow Localization Failure Bounded Through Ductile Damage in Dynamically Loaded Sheets 559 569 EN F Hosseini Mansoub Department of Mechanical Engineering, University Campus, University of Guilan, Rasht, Iran A Basti Department of Mechanical Engineering, University of Guilan, Rasht, Iran A Darvizeh Department of Mechanical Engineering, University of Guilan, Rasht, Iran A Zajkani Department of Mechanical Engineering, Imam Khomeini International University, Qazvin, Iran Journal Article 2020 09 30 In this paper, a new approach is proposed for stress state - dependent flow localization in bifurcation failure model bounded through ductile damage in dynamically loaded sheets. Onset of localized necking is considered in phenomenological way for different strain rates to draw the forming limit diagram (FLD). Using a strain metal hardening exponent in the Vertex theory related to the strain rate helps investigate rate- dependent metal forming limits. Besides, the paper utilizes the model of ductile damage as a function of strain condition, stress states (triaxiality and Lode parameters), and the symbols of stiffness strain to predict the onset of the necking. It is worth noting that updated level of elasticity modulus in the plastic deforming is attributed as an essential index for the ductile damage measuring. According to original formulations, a UMAT subroutine is developed in the finite element simulation by ABAQUS code to analyze and connect the related constitutive models. Results reveal that the FLD levels increase for St 13 material through enhancing the strain rate.