Implementation of Internal-State-Variable Based Model into Finite Element Code and its Applicability to Study the Tensile Behaviour of Type 316LN SS With Different Notch Radii

摘要

An attempt has been made towards the implementation of two-internal-variable model based on the evolution of forest dislocation density and mean free path with the plastic strain into finite element code via user-defined material subroutine using implicit Euler backward algorithm with radial-return scheme. The rate independent two-internal-variable model considers isotropic hardening and the parameters associated with the model are optimised by fitting uniaxial true stress-true plastic strain data. Applicability of the implemented scheme has been examined by simulating the tensile behaviour of type 316LN austenitic stainless steel with different U-notch radii as 1.25, 2.5 and 5 mm at 300 K. Good agreement between the predicted and experimental data has been observed. Detailed analysis showed notch-strengthening effect increases with decrease in notch radius at 300 K.