Dependency of the Young’s modulus to plastic strain in DP steels: a consequence of heterogeneity ?

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Date
2020
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Materials Today Communications
Abstract
The accurate springback prediction of dual phase (DP) steels has been reported as a major challenge. It was demonstrated that this was due to the lack of understanding of their nonlinear unloading behavior and especially the dependency of their unloading moduli on the plastic prestrain. An improved compartmentalized finite element model was developed. In this model, each element was assigned a unique linear elastic J2 plastic behavior without hardening. The model's novelty lied in the fact that: (i)a statistical distribution was discretized in a deterministic way and used to assign yield stresses to structures called compartments,(ii)those compartments were randomly associated with the elements through a random compartment element mapping (CEM). Multiple CEM were simulated in parallel to investigate the intrinsic randomness of the model. The model was confronted with experimental data extracted from the literature and it was demonstrated that the model was able to reproduce the dependence of the apparent moduli on the tensile prestrain. It was also observed that the evolution of the apparent moduli was predicted even if it was not an explicit input of the experimental dataset used to identify the input parameters of the model. It was then deduced that the shape of the hardening and the dependency of moduli on the prestrain were two manifestations of a single cause: the heterogeneous yield stress in DP steels.
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Keywords
Dual phase steels, Apparent modulus, Young's modulus evaluation, Heterogeneity, Springback, UD College of Engineering, CoE_Djibouti, Université de Djibouti, Djibouti, Engineering
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