Optimisation of mixed hardening material constitutive models for weld residual stress simulation using the NeT task group 1 single bead on plate benchmark problem.

Smith, MC; Nadri, B; Smith, AC; Carr, DG; Bendeich, PJ; Edwards, L

Optimisation of mixed hardening material constitutive models for weld residual stress simulation using the NeT task group 1 single bead on plate benchmark problem.

Date

2009-07-26

Authors

Publisher

American Society of Mechanical Engineers (ASME)

Abstract

A single weld bead deposited on a flat plate is a deceptively simple problem that is in practice a challenge for both measurement and prediction of weld residual stresses. Task Group 1 of the NeT collaborative network has examined this problem in an extensive programme of measurement and simulation extending from 2002 to 2008. As a result, the NeT bead on plate forms an ideal benchmark problem for the development of weld residual stress simulation techniques. One of the conclusions of NeT Task Group 1 is that the most accurate predictions of weld residual stresses in austenitic steels are achieved using mixed isotropic-kinematic material constitutive models. However, the use of these models can require both extensive materials data, and compromises in fitting either the monotonic or cyclic responses. This paper reports a detailed matrix of sensitivity studies aimed at optimising the behaviour of mixed hardening models in welding simulation, using the Lemaitre-Chaboche formulation in the ABAQUS finite element code. Predicted stresses and strains in the NeT bead on plate specimen are compared with the extensive database of residual stress measurements. Further studies examine sensitivity to the handling of high temperature inelastic strains, using a novel two-stage annealing functionality implemented within ABAQUS. The results show that, overall, the most accurate predictions are made if the Lemaitre-Chaboche parameters are optimised to fit the monotonic response over the first 2% of plastic strain. However, further improvements in prediction could be achieved if the constitutive model were capable of independently fitting both the monotonic and saturated cyclic response of the material.

Keywords

Residual stresses, Simulation, Benchmarks, Hardening, Welded joints, Austenitic steels

Citation

Smith, M. C., Nadri, B., Smith, A. C., Carr, D. G., Bendeich, P. J., & Edwards, L. (2009). Optimisation of mixed hardening material constitutive models for weld residual stress simulation using the NeT task group 1 single bead on plate benchmark problem. Paper presented to the ASME 2009 Pressure Vessels and Piping Conference (PVP2009), 26th – 30th July 2009. Prague, Czech Republic: Hilton Prague. In Proceedings of the ASME Pressure Vessels and Piping Conference 2009 - Materials and Fabrication, Parts A and B, 6, pp. 303-318 (PVP2009-77158). doi:10.1115/PVP2009-77158