The implementation of a constitutive model with weighted dynamic recovery and its application

An explicit updating algorithm has been developed, based on the backward Euler integration methods for the modified Armstrong-Frederick type of nonlinear kinematic hardening constitutive model with weighted dynamic recovery. This has been achieved by considering the consistency of the updated stresses, back stresses and the yield function, resulting in three sets of nonlinear equations which are then linearised using the Newton method. The developed algorithm and a linearised version have been implemented in ABAQUS as user material subroutines. Numerical simulations show that as long as the size of the incremental plastic strain is small so that k2i delta p <<0.1, both the linearised and the nonlinear algorithm converge to the same solution. Numerical analysese have been conducted to predict the strain response near the fuel ventilation hole on a wing pivot fitting of fighter aircraft, and good agreement has been observed between the experimental and numerical results.