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Dynamic Characterization and Constitutive Modelling of ARMSTAL 500 Steel

Tria D. E., Trębiński R.

Problemy Mechatroniki : uzbrojenie, lotnictwo, inżynieria bezpieczeństwa

2015

Vol. 6, Nr 3 (21)

19-40

The behaviour of a high strength steel (ARMSTAL 500) has been investigated using a combination of quasistatic and dynamic tests for a wide strain-rate range 1·10⁻⁴ – 3·10³ s⁻¹. A uniaxial testing machine and a Split Hopkinson Pressure Bar (SHPB) have been used under well controlled testing conditions. Next, the effect of the strain hardening, the strain rate hardening, loading history and stress triaxiality on the strength and ductility of the material has been studied. The present work also describes constitutive and damage models and their implementation available in the nonlinear finite element code LS DYNA. Calibration of constitutive model parameters and damage criteria is most often accomplished via regression techniques applied to laboratory data. A 3D numerical simulation of perforation of ARMSTAL 500 plates with 7.62 × 51 mm AP projectile were carried out with detailed models of target and compared with experiment in order to validate the calibrated models. As it will be shown, ARMSTAL 500 steel is a high strength steel with modest strain-rate sensitivity. The study indicates that the penetration depth can be predicted quantitatively and qualitatively with MJC hardening parameters calibrated from compression tests. The Modified Johnson–Cook constitutive model with Cockcroft and Latham failure model can predict the projectile residual speed and the fragmentation process followed very closely by MJC failure criteria.

Error estimation and adaptivity for nonlinear FE analysis

Huerta A., Rodriguez-Ferran A., Diez P.

International Journal of Applied Mathematics and Computer Science

2002

Vol. 12, no 1

59-70

An adaptive strategy for nonlinear finite-element analysis, based on the combination of error estimation and h-remeshing, is presented. Its two main ingredients are a residual-type error estimator and an unstructured quadrilateral mesh generator. The error estimator is based on simple local computations over the elements and the so-called patches. In contrast to other residual estimators, no flux splitting is required. The adaptive strategy is illustrated by means of a complex nonlinear problem: the failure analysis of a single-edge notched beam. The quasi-brittle response of concrete is modelled by means of a nonlocal damage model.