Anisotropy-corrected MTS constitutive strength modeling in HY-100 steel

Phenomenological plastic flow stress models are used extensively in the simulation of large deformations of metals at high strain-rates and high temperatures. Several such models exist and it is difficult to determine the applicability of any single model to the particular problem at hand. Ideally, the models are based on the underlying (subgrid) physics and therefore do not need to be recalibrated for every regime of application. In this work we compare the Johnson-Cook, Steinberg-Cochran-Guinan-Lund, Zerilli-Armstrong, Mechanical Threshold Stress, and Preston-Tonks-Wallace plasticity models. We use OFHC copper as the comparison material because it is well characterized. First, we determine parameters for the specific heat model, the equation of state, shear modulus models, and melt temperature models. These models are evaluated and their range of applicability is identified. We then compare the flow stresses predicted by the five flow stress models with experimental data for annealed OFHC copper and quantify modeling errors. Next, Taylor impact tests are simulated, comparison metrics are identified, and the flow stress models are evaluated on the basis of these metrics. The material point method is used for these computations. We observe that the all the models are quite accurate at low temperatures and any of these models could be used in simulations. However, at high temperatures and under high-strain-rate conditions, their accuracy can vary significantly.

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“…The Mechanical Threshold Stress (MTS) model (Follansbee and Kocks (1988); Goto et al (2000b); Kocks (2001)) has the form…”

Section: Mts Flow Stress Modelmentioning

confidence: 99%

Effect of strain rate on microstructure of polycrystalline oxygen-free high conductivity copper severely deformed at liquid nitrogen temperature

Zhang

Shim

2010

Acta Materialia

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“…The Mechanical Threshold Stress (MTS) model (Follansbee and Kocks, 1988;Goto et al, 2000b) gives the following form for the flow stress…”

Section: Mechanical Threshold Stress Modelmentioning

confidence: 99%

“…Shear modulus models for 4340 steel A.3.1. MTS shear modulus model The Varshni-Chen-Gray shear modulus model has been used in conjunction with the MTS plasticity models by Chen and Gray (1996) and Goto et al (2000b). Hence, we refer to this model as the MTS shear modulus model.…”

Section: A21 Steinberg-cochran-guinan Modelmentioning

confidence: 99%

“…The Mechanical Threshold Stress (MTS) model (Follansbee and Kocks [14], Kocks [29]) is a physically-based model that can be used for the range of temperatures and strain rates of interest in these simulations. In the absence of any MTS models specifically for 4340 steels, an existing MTS model for HY-100 steel (Goto et al [16,17]) was initially explored as a surrogate for 4340 steel. However, the HY-100 model failed to produce results that were in agreement with experimental stress-strain data for 4340 steel.…”

Section: Introductionmentioning

confidence: 99%

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The Mechanical Threshold Stress model for various tempers of AISI 4340 steel

Banerjee

2007

International Journal of Solids and Structures

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Numerical simulations of high strain rate and high temperature deformation of pure metals and alloys require realistic plastic constitutive models. Empirical models include the widely used Johnson-Cook model and the semi-empirical Steinberg-Cochran-Guinan-Lund model. Physically based models such as the Zerilli-Armstrong model, the Mechanical Threshold Stress model, and the Preston-Tonks-Wallace model are also coming into wide use. In this paper, we determine the Mechanical Threshold Stress model parameters for various tempers of AISI 4340 steel using experimental data from the open literature. We also compare stress-strain curves and Taylor impact test profiles predicted by the Mechanical Threshold Stress model with those from the Johnson-Cook model for 4340 steel. Relevant temperature-and pressuredependent shear modulus models, melting temperature models, a specific heat model, and an equation of state for 4340 steel are discussed and their parameters are presented.

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“…In the first part, the plasticity model is described. This model is based on the Mechanical Threshold Stress (MTS) approach [5][6][7] for dynamic yielding which was originally developed by Mecking and Kocks [8]. In the second part, our proposed nucleation and growth model is presented.…”

Section: Introductionmentioning

confidence: 99%