Comparative study on mechanical behavior of low temperature application materials for ships and offshore structures: Part II – Constitutive model

Austenitic stainless steel (ASS), aluminum alloy, and nickel steel alloy are strong temperature- and strain-rate-dependent materials. They exhibit very complicated nonlinear behaviors during plastic deformation. While the typical characteristics of their nonlinear behaviors, including second hardening and strain-rate sensitivity, can be easily identified through experimental investigation, a useful numerical model is not available. The unavailability of such a model is because of the wide variance in the nonlinearities of the materials. In the present study, a unified constitutive model is proposed for representing the temperature- and strain-rate-dependent material nonlinearities in ASS and aluminum and nickel steel alloys. Based on the Bodner model, a strain-hardening function was developed for expressing second hardening as well as strain-rate sensitivity. To provide unified material parameters for the hardening exponent and strain-rate control, a new type of material parameter identification method is proposed. Based on the proposed constitutive model, in conjunction with both a damage model and the material parameters, a verification study is conducted. The experimental results of both Park et al. [1] and Tomita and Iwamoto [2], which are valid within a temperature range of 80–345 K and a strain-rate range of 0.0005–500/s, are compared with the numerical results of this study.