scholarly journals A Fully Coupled Thermal-Structural Finite Element Analysis of a Low-Carbon Steel Bar Using an Improved Material Model For Ductile-to-Brittle Transition at High Strain Rates

2011 ◽  
Vol 19 (1) ◽  
Author(s):  
Ladislav Écsi ◽  
Pavel Élesztős
Keyword(s):  
High Strain ◽  
Low Carbon Steel ◽  
Material Model ◽  
Strain Rates ◽  
Low Carbon ◽  
Element Analysis ◽  
Brittle Transition ◽  
Steel Bar ◽  
Ductile To Brittle Transition ◽  
Fully Coupled

An Improved Heat Equation to Model Ductile-to-Brittle Failure Mode Transition at High Strain Rates Using Fully Coupled Thermal-Structural Finite Element Analysis

2014 ◽  
Vol 354 ◽  
pp. 1-23 ◽  
Author(s):  
Ladislav Écsi ◽  
P. Élesztős
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Heat Equation ◽  
Brittle Failure ◽  
High Strain ◽  
Strain Rates ◽  
Mode Transition ◽  
Element Analysis ◽  
Failure Mode Transition ◽  
Fully Coupled

In this paper a universal heat equation for fully coupled thermal structural finite element analysis of deformable solids capable of predicting ductile-to-brittle failure mode transition at high strain rates is presented. In the problem mathematical formulation appropriate strain measures describing the onset and the growth of ductile and total damage and heat generation rate per unit volume to model dissipation-induced heating have been employed, which were extended with the heat equation. The model was implemented into a finite element code utilizing an improved weak form for updated Lagrangian formulation, an extended NoIHKH material model for cyclic plasticity of metals applicable in wide range of strain rates and the Jaumann rate in the form of the Green-Naghdi rate in the co-rotational Cauchy’s stress objective integration. The model verification showed excellent agreement with the modelled experiment at low strain rates. Plastic bending of a cantilever has been studied at higher strain rates. A few selected analysis results are presented and briefly discussed.

scholarly journals Determining Johnson-Cook Constitutive Equation for Low-Carbon Steel via Taylor Anvil Test

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 4821
Author(s):  
Lenka Kunčická ◽  
Miroslav Jopek ◽  
Radim Kocich ◽  
Karel Dvořák
Keyword(s):  
Carbon Steel ◽  
Constitutive Equation ◽  
Low Carbon Steel ◽  
High Volume ◽  
Material Model ◽  
Strain Rates ◽  
Low Carbon ◽  
Sequential Machines ◽  
High Volume Production ◽  
Volume Production

Tristal steel is low-carbon construction-type steel widely used in the automotive industry, e.g., for braking components. Given the contemporary demands on the high-volume production of such components, these are typically fabricated using automatic sequential machines, which can produce components at strain rates up to 103 s−1. For this reason, characterising the behaviour of the used material at high strain rates is of the utmost importance for successful industrial production. This study focuses on the characterisation of the behaviour of low-carbon steel via developing its material model using the Johnson-Cook constitutive equation. At first, the Taylor anvil test is performed. Subsequently, the acquired data together with the results of observations of structures and properties of the tested specimens are used to fill the necessary parameters into the equation. Finally, the developed equation is used to numerically simulate the Taylor anvil test and the predicted data is correlated with the experimentally acquired one. The results showed a satisfactory correlation of the experimental and predicted data; the deformed specimen region featured increased occurrence of dislocations, as well as higher hardness (its original value of 88 HV increased to more than 200 HV after testing), which corresponded to the predicted distributions of effective imposed strain and compressive stress.

scholarly journals Ductile-to-Brittle Transition and Brittle Fracture Stress of Ultrafine-Grained Low-Carbon Steel

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1634
Author(s):  
Tadanobu Inoue ◽  
Hai Qiu ◽  
Rintaro Ueji ◽  
Yuuji Kimura
Keyword(s):  
Grain Size ◽  
Carbon Steel ◽  
Brittle Fracture ◽  
Fracture Stress ◽  
Low Carbon Steel ◽  
Carbon Steels ◽  
Low Carbon ◽  
Brittle Transition ◽  
Wide Range ◽  
Ductile To Brittle Transition

Ductile-to-brittle transition (DBT) temperature and brittle fracture stress, σF, are important toughness criteria for structural materials. In this paper, low-carbon steels with an ultrafine elongated grain (UFEG) structure (transverse grain size 1.2 μm) and with two ferrite (α)- -pearlite structure with grain sizes 10 µm and 18 µm were prepared. The UFEG steel was fabricated using multipass warm biaxial rolling. The tensile tests with a cylindrical specimen and three-point bending tests with a single-edge-notched specimen were performed at −196 °C. The local stress near the notch was quantitatively calculated via finite element analysis (FEA). The σF for each sample was quantified based on the experimental results and FEA. The relationship between σF and dα in the wide range of 1.0 μm to 138 μm was plotted, including data from past literature. Finally, the conditions of grain size and temperature that cause DBT fracture in low-carbon steel were shown via the stress−d−1/2 map. The results quantitatively showed the superiority of α grain size for brittle fracture.

Measurement and Calculation of Elastic Properties in Low Carbon Steel Sheet

2005 ◽  
Vol 495-497 ◽  
pp. 1591-1596 ◽  
Author(s):  
Vladimir Luzin ◽  
S. Banovic ◽  
Thomas Gnäupel-Herold ◽  
Henry Prask ◽  
R.E. Ricker
Keyword(s):  
Carbon Steel ◽  
Elastic Property ◽  
Elastic Properties ◽  
Steel Sheet ◽  
Low Carbon Steel ◽  
Low Carbon ◽  
Forming Process ◽  
Element Analysis ◽  
Wide Range ◽  
Carbon Steel Sheet

Low carbon steel (usually in sheet form) has found a wide range of applications in industry due to its high formability. The inner and outer panels of a car body are good examples of such an implementation. While low carbon steel has been used in this application for many decades, a reliable predictive capability of the forming process and “springback” has still not been achieved. NIST has been involved in addressing this and other formability problems for several years. In this paper, texture produced by the in-plane straining and its relationship to springback is reported. Low carbon steel sheet was examined in the as-received condition and after balanced biaxial straining to 25%. This was performed using the Marciniak in-plane stretching test. Both experimental measurements and numerical calculations have been utilized to evaluate anisotropy and evolution of the elastic properties during forming. We employ several techniques for elastic property measurements (dynamic mechanical analysis, static four point bending, mechanical resonance frequency measurements), and several calculation schemes (orientation distribution function averaging, finite element analysis) which are based on texture measurements (neutron diffraction, electron back scattering diffraction). The following objectives are pursued: a) To test a range of different experimental techniques for elastic property measurements in sheet metals; b) To validate numerical calculation methods of the elastic properties by experiments; c) To evaluate elastic property changes (and texture development) during biaxial straining. On the basis of the investigation, recommendations are made for the evaluation of elastic properties in textured sheet metal.

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