A novel approach for determining material constitutive parameters for a wide range of triaxiality under plane strain loading conditions

• A new plane-strain double-notched specimen is proposed to obtain the material constitutive parameters.
• The specimen can yield stress states at low and negative stress triaxiality state regions.
• The triaxiality state is found to be proportional to the specimen gauge orientation.
• A forward sequential optimization strategy for the identification of material plasticity is developed.
• The reduced Johnson Cook model was found suitable to describe the workpiece fracture locus.

This paper focuses on material constitutive models for plane strain applications such as orthogonal cutting. It presents a novel approach to determine the material model parameters which utilizes a new, adjustable stress state specimen, Digital Image Correlation (DIC) measurements, and an inverse method for parameter identification. The proposed double-notched specimen is purposely designed to allow the identification of damage and fracture parameters for the plane strain condition. The corresponding equivalent plastic strains at different stages of deformation and damage were calculated from DIC measurements. The elastic modulus and yield surface were obtained using a numerical optimization based inverse method. Ultimately, the fracture locus was obtained and the parameters in the Rice and the reduced form of the Johnson Cook (JC) damage models were identified. The model validation is also provided.